Archive | Hardware

SHVPS PCB v5, Low voltage testing procedure

The following testing procedure should be printed and marked for debugging and record keeping.

Name of testing agent:

Date:

Model (kV):

Board Name*:

I2C Address*:

*Assign a name and a I2C address to your board. The name and address will be stored at a later stage in the micro-controller. The name helps differentiate different HVPSs, and because they all have their own personality, and maximal voltage, we like to give them a distinctive name. The I2C address is used if you want to assemble several HVPS into a multi-channel high-voltage power supply (MHVPS). Valid addresses are between 10 and 127.

  1. Check all the resistor values. Place a tick in the box if the marking on the resistor matches the value below.
    ☐ R1 = 27R0
    ☐ R2 = 1500
    ☐ R3 = 1001
    ☐ R4 = 27R0
    ☐ R5 = 1001
    ☐ R7 = 1001
    ☐ R8 = 1500
    ☐ R9 = 9532 (5kV model)
    ☐ R9 = 8062 (3kV model)
    ☐ R9 = 1203 (2kV model)
    ☐ R9 = 8872 (1.2kV model)
    ☐ R9 = 2153 (500V model)
    ☐ R10 = 1001
    ☐ R11 = 1002
  2. Check the polarity of the components below. Place a tick in the box if the polarity matches the polarity on the PCB overlay.
    ☐ D1
    ☐ D2
    ☐ D3
    ☐ C3
    ☐ Q1
    ☐ Q2
    ☐ OC1
    ☐ OC2
  3. Measure the resistance between the 5V rail and GND.
    How to conduct test: Use the rail board to make a connection to the 5V and ground rails using the 10-pins connector and measure the resistance with a multimeter. (If you need to build your own rail board, solder a red wire to pin 2 (5V) and a black wire to pin 4 (GND), as shown on picture below.) The switch s2 must be in position 0.

    Purpose of test: To determine if there are any shorts between the power rails before applying power.
    Resistance between red and black wire (Jumper h5V should be in the on position at this stage):

    ☐ Resistance is approximately 1.1kΩ

  4. Measure the output of the 5V regulator.
    How to conduct test:

    *Leave the rail board connected for this test*
    a) Place the jumper h5v in the OFF position
    b) Plug in the 7.5V adapter.
    Order code: Digikey ‎237-2156-ND‎
    Part number: WSX075-3200-13‎
    Description: AC/DC WALL MNT ADAPTER 7.5V 24W

    c) Measure the voltage of the regulator relative to ground. The easiest way to do this is to use the rail board from the last step to connect to ground and to probe the large tab of Reg1 with a multimeter probe. Record the voltage below.

    Purpose of test: To determine if the regulator is functioning correctly without the remainder of the circuit connected.
    Voltage with jumper h5v in the OFF position:

    ☐ Voltage is approximately 5V

  5. Test if the circuit has power.
    How to conduct test:

    *Leave the rail board and the adapter connected for this test*
    a) Place the jumper h5v in the ON position
    b) Observe D1
    c) If LED D1 glows green, place a tick the check box and continue. If not, remove the jumper and investigate for a cause.

    Purpose of test: To determine if there are any components which are consuming too much power due to assembly errors or faulty components.
    ☐ D1 glows green
  6. Test the power pin on the microcontroller header and the HV indicator LED
    How to conduct test:

    *Leave the rail board and the adapter connected for this test. Leave the power jumper in the ON position*
    a) Insert the dummy microcontroller. The dummy microncontroller is a small board which imitates the functions of the arduino micro.

    b) Ensure that the switch on the dummy microcontroller is in the ‘D3 test’ position.
    c) Observe the LED on the dummy microcontroller. If the LED glows orange, place a tick in the box below. If not, remove the power jumper (h5v) and check for a cause.
    d) Observe LED D3. If LED D3 glows red, place a tick in the box below. If not, remove the power jumper (h5v) and check the polarity of LED D3.

    Purpose of test:
    Step c) tests whether the power pins on the microcontroller are connected to power. Step d) tests if the HV indicator LED is functional.
    ☐ The LED on the dummy microcontroller glows orange
    ☐ LED D3 glows red when the switch is in the ‘D3 test’ position
  7. Check if the high frequency switching circuit is functioning correctly
    How to conduct test:
    *Leave the rail board, adapter, and dummy microcontroller connected for this test. Leave the power jumper in the ON position*
    a) Place a jumper on H2 in the ‘Button’ position.
    b) Connect the COM port of the multimeter to the GND wire of the rail board.
    c) Using a probe measure the voltage of the via close to R4. Record the voltage when S1 is depressed and when pressed.

    Purpose of test: This test measures the output from Q1. The voltage must toggle from rail to rail to turn the infrared LEDs on and off.
    Voltage on via close to R4 when S1 is depressed:

    ☐ voltage on via is ~5V when button is depressed

    Voltage on via close to R4 when S1 is pressed:

    ☐ voltage on via is ~0V when button is pressed

  8. Check all the components powering the EMCO DC-DC converter
    How to conduct test: 
    *Leave the rail board, adapter, dummy microcontroller, and multimeter connected for this test. The power jumper must be in the ON position*
    a) Place the safety switch S2 is in the On position (indicated on the board with a small ‘1’ to the right of the switch)
    b) Ensure that the COM port of the multimeter is still connected to the GND wire of the rail board.
    c) Place the switch on the dummy microcontroller into the ‘EMCO test’ position
    d) Using a probe measure the voltage on pin pair 2-5 (see picture) and record the value below.
    e) Place the switch on the dummy microcontroller into the ‘D3 test’ position
    f) Using a probe measure the voltage on pin pair 2-5 (see picture) and record the value below.

    Purpose of test: To test if the circuit providing power to the EMCO is able to provide 5V.
    Voltage on pin pair 2-5 when switch is in ‘EMCO test’ position:

    ☐ voltage on pin pair 2-5 is ~5V when the switch is in EMCO test position

    Voltage on pin pair 2-5 when switch is in ‘D3 test’ position:

    ☐ voltage on pin pair 2-5 is drifting towards zero when the switch is in D3 test position

If your HVPS has passed all the low voltage tests above (all check boxes ticked), you can continue with the soldering of the high voltage components (section 4 of the assembly page).

Assembly procedure for SHVPS v5b1

1 Pre-assembly Procedure

  • Take a PCB and clean it with isopropyl alcohol. Wear gloves during assembly.

2 Soldering of Low Voltage Components

  1. Solder dual MOSFETs Q1 and Q2. Make sure that the notch on the chip is aligned with the notch on the PCB overlay.
    Order code: Digikey FDS8858CZCT-ND
    Part number: FDS8858CZ
    Description: Dual MOSFET, N and P Channel, 8.6 A, 30 V, 17 mohm, 10 V, 1.6 V
  2. Solder capacitors C1, C2, C5, and C9. Polarity is not important.
    Order code: Digikey 1276-3038-6-ND
    Part number: CL31A106KAHNFNE
    Description: 10µF ±10% 25V Ceramic Capacitor X5R 1206 (3216 Metric)
  3. Solder capacitors C8. Polarity is not important.
    Order code: Digikey 1276-1921-1-ND
    Part number: CL10B103KB8NCNC
    Description: 10000pF ±10% 50V Ceramic Capacitor X7R 0603 (1608 Metric)
  4. Solder capacitor C4_c. Polarity is not important.
    Order code: Digikey ‎399-1285-1-ND
    Part number: C1206C334K3RACTU
    Description: 0.33µF ±10% 25V Ceramic Capacitor X7R 1206 (3216 Metric)
  5. Solder the resistors R1 and R4. Polarity is not important.
    Order code: Digikey ‎408-1908-1-ND‎
    Part number: ‎HRG3216Q-27R0-D-T1
    Description: 27 Ohms ±0.5% 1W Chip Resistor 1206 (3216 Metric) Anti-Sulfur, Automotive AEC-Q200, Moisture Resistant Thin Film
  6. Solder resistors R2 and R8. Polarity is not important.
    Order code: Digikey ‎CR1206-FX-1500ELFCT-ND‎
    Part number: CR1206-FX-1500ELF
    Description: SMD Chip Resistor, Thick Film, 150R, 1%, 0.25W, 1206
  7. Solder resistors R3, R5, R7, and R10.
    Order code: Digikey ‎541-2245-1-ND‎
    Part number: ‎RCA12061K00FKEA‎
    Description: 1 kOhms ±1% 0.25W, 1/4W Chip Resistor 1206 (3216 Metric) Anti-Sulfur, Automotive AEC-Q200 Thick Film
  8. Solder resistor R11.
    Order code: Digikey RHM10KYCT-ND
    Part number: LTR18EZPF1002
    Description: 10 kOhms ±1% 0.75W, 3/4W Chip Resistor Wide 1206 (3216 Metric)
  9. Solder resistor R9.
    The value of R9 depends on the output voltage of the HVPS. Please select the appropriate value below.
    For the 5kV model:
    Order code: Digikey 311-95.3KFRCT-ND‎
    Part number: ‎RC1206FR-0795K3L‎
    Description: 95.3 kOhms ±1% 0.25W, 1/4W Chip Resistor 1206 (3216 Metric) Moisture Resistant Thick Film
    For the 3kV model:
    Order code: Digikey P80.6KFCT-ND
    Part number: ERJ-8ENF8062V
    Description: RES SMD 80.6K OHM 1% 1/4W 1206
    For the 2kV model:
    Order code: Digikey P120KFCT-ND
    Part number: ERJ-8ENF1203V
    Description: RES SMD 120K OHM 1% 1/4W 1206
    For the 1.2kV model:
    Order code: Farnell 2327378
    Part number: ERJP08F8872V
    Description: PANASONIC ELECTRONIC COMPONENTS  ERJP08F8872V  SMD Chip Resistor, Thick Film, 88.7 kohm, 500 V, 1206 [3216 Metric], 660 mW, ± 1%, ERJP08 Series
    For the 500V model:
    Order code: Farnell 2327103
    Part number: ERJP08F2153V
    Description: PANASONIC ELECTRONIC COMPONENTS  ERJP08F2153V  SMD Chip Resistor, Thick Film, 215 kohm, 500 V, 1206 [3216 Metric], 660 mW, ± 1%, ERJP08 Series
    More details on the design of the voltage divider and the resistance values.

  10. Solder D1 (Green). Note the polarity! The green markings on top of the LED should face the thick line on the PCB overlay.
    Order code: Digikey ‎67-1002-1-ND‎
    Part number: SML-LX1206GW-TR
    Description: LED, QuasarBrite, Green, SMD, 3.2mm x 1.6mm, 20 mA, 2.2 V, 565 nm
  11. Solder D3 (Red). Note the polarity! The green markings on top of the LED should face the thick line on the PCB overlay.
    Order code: Digikey ‎67-1003-1-ND‎
    Part number: SML-LX1206IW-TR
    Description: LED, QuasarBrite, Red, SMD, 3.2mm x 1.6mm, 20 mA, 2 V, 635 nm
  12. Solder Reg1.
    Order code: Digikey NCP1117ST50T3GOSCT-ND
    Part number: ‎NCP1117ST50T3G‎
    Description: Linear Voltage Regulator IC Positive Fixed 1 Output 5V 1A SOT-223
  13. Solder D2. Note the polarity! The line on the diode should match the line on the PCB overlay.
    Order code: Digikey 497-5574-1-ND‎
    Part number: STPS2L40U
    Description: Schottky diode, 2 A, 40 V, DO-214AA=SMB
  14. Solder S1. Polarity is not important
    Order code: Digikey SW791-ND‎
    Part number: ‎B3FS-1050‎
    Description: Tactile Switch SPST-NO Top Actuated Surface Mount
  15. Solder C3. Note the polarity! The line on the diode should match the marking on the PCB overlay.
    Order code: Digikey ‎399-8415-1-ND‎
    Part number: T491D227K016AT
    Description: Surface Mount Tantalum Capacitor, 220 µF, 16 V, T491 Series, ± 10%, 2917 [7343 Metric]
  16. Solder L1. Polarity is not important.
    Order code: Digikey ‎732-1701-1-ND‎
    Part number: ‎7447709821‎
    Description: 820µH Shielded Wirewound Inductor 950mA 1 Ohm Max Nonstandard
  17. Solder S2.
    Order code: Digikey ‎563-1571-ND‎
    Part number: MHS122-1‎
    Description: Slide Switch SPDT Through Hole, Right Angle
  18. Solder edge connector K56GVFTRDC. The edge connector is supplied in long strips. Using a pair of pliers break off a row of 10 pins.
    Order code: Digikey ‎3M156872-36-ND‎
    Part number: ‎929835-01-36-RK‎
    Description: Connector Header Through Hole, Right Angle 36 position 0.100″ (2.54mm)
  19. Solder h5V. Polarity is not important.
    Order code: Digikey ‎732-5316-ND
    Part number: 61300311121
    Description: Pin header 3P Single row / straight / without shroud
  20. Solder hD1, hD3, hS1, hS2 if you intend to have components D1, D3, S1, S2 panel mounted. Polarity for these headers is not important.
    Order code: Digikey SAM1121-02-ND‎
    Part number: SSA-102-S-G
    Description: SAMTEC  SSA-102-S-G  Board-To-Board Connector, SSA Series, 2 Contacts, Receptacle, 2.54 mm, Through Hole, 1 Rows
    If you intend to place the board in the minimalistic enclosure, soldering these headers is not necessary. If you intend to place the board in the full enclosure, only headers hS1 and hS2 are necessary.
  21. Solder H2. Polarity is not important.
    Order code: ‎Digikey 952-2120-ND‎
    Part number: M20-9980345
    Description: Board-To-Board Connector, Vertical, M20 Series, 6 Contacts, Header, 2.54 mm, Through Hole, 2 Rows
  22. Solder J1. 
    Order code: Digikey ‎CP-102BH-ND‎
    Part number: PJ-102BH‎
    Description: Power Barrel Connector Jack 2.50mm ID (0.098″), 5.50mm OD (0.217″) Through Hole, Right Angle
  23. Solder header sockets for microcontroller. The header sockets are supplied in long strips. Score the plastic with a craft knife and break off 17 contacts with a pair of pliers. Clean up the rough edge with the craft knife or sandpaper.
    Order code:  Digikey ‎929974-01-36-ND‎
    Part number: ‎929974-01-36‎
    Description: 36 Position Receptacle Connector 0.100″ (2.54mm) Through Hole Tin-Lead
  24. Prepare optocouplers OC1 and OC2. Please follow the instructions below:
    Bending of the leads:
    Bend the leads as shown in the series of images below.
    bending_oc
    Mark pin 1 (before painting):
    Bend the tip of pin 1 so that it can be identified after painting the optocoupler.
    Painting of the optocoupler:
    The optocoupler is painted to prevent inteference from neighbouring optocouplers and IR light which is present in the environment. Tipp-Ex is used because it creates a relatively good barrier to IR light and is easy to apply. Simply paint the plastic body of the optocoupler with a single layer of Tipp-Ex and let it dry. It is best to do it rapidly and in single strokes. Making multiple passes results in a sticky mess which is very unsightly.
    Mark pin 1 (after painting):
    Use a permanent pen to mark pin 1 with a dot next to the pin.
    METADATA-START
    Order code: MPI Distribution AG OC100G
    Part number: OC100G
    Description: HV Opto-Coupler 10 kV
  25. Solder optocouplers OC1 and OC2. Make sure that the polarity is correct.
    step_24
    (unlike what is shown on the picture above, the EMCO DC/DC converter and resistor R6 are not yet soldered)
  26. Place the jumper on h5V in the ON position, and the jumper h2 in the Button position.
    Order code:Digikey ‎S9001-ND‎
    Part number: SPC02SYAN‎
    Description: 2 (1 x 2) Position Shunt Connector Black Closed Top 0.100″ (2.54mm) Gold
  27. You are ready to test the low voltage part of your HVPS

3 Testing procedure of the Low-voltage part of the HVPS

Before assembling the High-voltage components, go through the low-voltage testing procedure and ensure that the circuit is working properly. Only proceed with the assembly of the HV components if all the low voltage tests have passed.

4 Soldering of High Voltage Components

  1. Solder R6. Do not fully insert this resistor. Insert it so that 2mm of the leads can be seen above the top surface of the PCB.
    The value of R6 depends on the output voltage of the HVPS. Please select the appropriate value below.
    For the 5kV model:
    Order code: Digikey SM102031006FE-ND‎
    Part number: SM102031006FE
    Description: OHMITE  SM102031006FE  Through Hole Resistor, Slim-Mox, 100 Mohm, 5 kV, Radial Leaded, 1 W, ± 1%, Slim-Mox Series
    For the 3kV model:
    Order code: Digikey SM102035005FE-ND
    Part number: SM102035005FE
    Description: RES 50M OHM 1W 1% RADIAL
    For the 2kV model:
    Order code: Digikey SM102035005FE-ND
    Part number: SM102035005FE
    Description: RES 50M OHM 1W 1% RADIAL
    For the 1.2kV model:
    Order code:  Digikey 22MGBCT-ND
    Part number: HHV-50FR-52-22M
    Description: RES 22M OHM 1/2W 1% AXIAL
    For the 500V model:
    Order code:  Digikey 22MGBCT-ND
    Part number: HHV-50FR-52-22M 
    Description: RES 22M OHM 1/2W 1% AXIAL
    More details on the design of the voltage divider and the resistance values.
    hv_step_1
  2. Solder EMCO1
    EMCO1 is the DC/DC converter of the HVPS, and its voltage rating defines the maximal output voltage of the HVPS. Use the following values:
    For the 5kV model:
    Order code: Digikey ‎1470-3217-ND
    Part number: AG50P-5
    Description: 5 kV AG Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 3kV model:
    Order code: Digikey 1470-3214-ND
    Part number: AG30P-5
    Description: 3 kV AG Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 2kV model:
    Order code: Digikey 1470-3211-ND
    Part number: AG20P-5
    Description: 2 kV AG Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 1.2kV model:
    Order code: EMCO/Condatas AG12P-5
    Part number: AG12P-5
    Description: 1.2 kV AG Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 500V model:
    Order code: Digikey 1470-3207-ND
    Part number: AG05P-5
    Description: 500 V AG Series Isolated, Proportional DC To HV DC Converter 5V input
    hv_step_2
  3. Solder the red HV socket H3
    Order code: Digikey ‎486-3655-ND‎
    Part number: 0040.1102
    Description: Socket ø 2 mm red, 0040.1102, Schurter
    hv_step_3
  4. Solder the black HV socket H3
    Order code: Digikey 486-3654-ND
    Part number: 0040.1101
    Description: Socket ø 2 mm black, 0040.1101, Schurter
    hv_step_4

5 Testing procedure of the High-voltage part of the HVPS

Once you have finished the assembly of the high-voltage components, you are ready to test the high-voltage portion of the circuit. Follow these instructions.

6 HV cables

  1. Cut the appropriate length of HV electrical cable.
    Red wire:
    Order code: Digikey W2722R-100-ND
    Part number: 2722/22 R/C
    Description: TEST LEAD 22AWG 5000V RED 100′
    Black wire:
    Order code: Digikey W2722B-100-ND
    Part number: 2722/22 B/C
    Description: TEST LEAD 22AWG 5000V BLACK 100′
  2. Manually enlarge the opening of the 2mm banana plug cover with a 3mm drill bit so it can fit over the HV cable.
    Red banana plug:
    Order code: ‎Digikey 501-1318-ND‎
    Part number: ‎‎5936-2‎
    Description: Banana Plug Connector Miniature Solder Red
    Black banana plug:
    Order code: Digikey ‎501-1345-ND
    Part number: ‎5936-0
    Description: Banana Plug Connector Miniature Solder Black
  3. Solder the banana plugs to the wires and install the protective covers
  4. At the other extremity of the cable, install the connector you need for your application. We use Alligator clips as versatile connectors.
    Red Clip:
    Order code: Digikey 36-5034-ND
    Part number: 5034
    Description: ALLIGATOR CLIP INSULATED RED
    Black Clip:
    Order code: Digikey 36-5035-ND
    Part number: 5035
    Description: ALLIGATOR CLIP INSULATED BLACK

7 Next steps

Once you have finished assembling and testing (Low voltage testing, High voltage testing) your HVPS, you should place in in a safe enclosure and proceed with configuration/calibration.

Minimal Enclosure

The minimal enclosure is a somewhat simpler enclosure than the full enclosure. It is therefore quicker to make and to assemble. Only the high voltage side of the circuit is protected, leaving the low-voltage side exposed, for easy access to the onboard buttons and LEDs. The minimal enclosure leaves the microcontroller exposed. Accidentally pressing the reset button on the microcontroller while the HVPS is in use leads to the transient application of the full voltage at the output. Consequently, a reset button protection is placed on the microcontroller to avoid undesired activation of the reset button.

Minimal enclosure protecting the high-voltage side of the circuit.

We use a Laser Engraver Trotec Speedy 300 to cut the parts required for the enclosure, and we have prepared files ready to be cut. We also have the Solidworks 3D files, so you can use whatever method you want to cut the parts or modify the enclosure to fit your needs.

Download the Solidworks files (Solidworks 2015): Download page –> Enclosure Files –> minimal_enclosure_Solidworks_files.zip

Cutting / Preparing the parts

The enclosure is made of 2different materials/parts

1.1 Enclosure Body

We use a 3 mm thick opaque PMMA for the main body of the enclosure. The file Download –> Enclosure Files –> minimal_enclosure.svg: contains all of the parts that need to be cut to assemble the main body. You need a plate of at least 220 mm x 100 mm to cut all the parts.

All the 3mm thick parts for the minimal enclosure

1.2 Front Panel

We use an engravable plastic TRANSPLY-HD with a black body and a white front layer. We  use the 1.5mm-thick plates. The file Download –> Enclosure Files –> minimal_enclosure_front_panel_model.svg can be used as a base for the front panel.

Model of the front panel for the minimal enclosure

The front panel is optional. It only provides text indication of the HVPS name and voltage rating.

The black filled shapes are engraved by the laser. The red and blue lines are the cut lines, matching the one on the part “Top”. We recommend that you indicate the name of the HVPS and the voltage rating (Edit the string that says Box name xx kV by the actual name and the voltage rating of your HVPS.) You can use the free space to add an image in relation with the name of your HVPS. See illustrative example at the top of the page…

A Laser works very well to engrave the panel, but is not optimal to cut the openings and external shape (ABS is not easy to cut with a Laser, because it melts). We suggest you try one of the following approaches:

  1. Start by cutting the openings before removing the protective cover on the top. The bits of molten ABS will land on the protective cover and will not stain the panel. Then remove the protective cover and proceed with the engraving step. The disadvantage with this method is that you need to precisely position the panel after cutting it so that the engraving match the geometry. But a very precise alignment is not required anyway.
  2. Start by removing the protective cover and replace it by masking tape. You can then do the three operation in one go without moving anything and in the logical order (engrave, cut red, cur blue). You must adapt the engraving parameters to go through the masking tape too. Masking tape burns without melting. This is the reason why we replace the plastic cover sheet with masking tape. Finish by removing the masking tape that will have caught the projections creating during the cutting step.

2 Assembling the parts

  1. Using glue for plastics (we use dichloromethane), assemble together the following parts (see picture below): Back, Front, Side (2x), Top.

    Pay attention to the position of the holes in the top part, which must be on the side of the front part. Also note the orientation of the slit in the front part, as indicated on the picture.
  2. Place double sided tape on the topside of the top part (do not cover the 2 holes), and position the engraved front panel.
  3. Slide the PCB into the cover, so that the PCB tab slides into the slit of the front part. Insert the Reset protection on the ICSP header of the microcontroller to avoid undesired activation of the button.
  4. Insert the 4 M2 inserts into the bottom part

    Alternatively, you can also tap the holes with a M2 thread, but you need to adapt the diameter of the holes before cutting the part.
  5. Place the 4 spacers on top of the inserts
  6. Place the PCB with the cover on top of the bottom part with spacers, and lock lock it in place with screws.

    You need 2 M2x6mm screw on the left, and 2 M2x20mm screws on the wight to go through the cover.

PCB and Schematics

1 Schematics of HVPS v4b2

Schematics of HVPS v4b2. Click to enlarge

2 PCB files for HVPS v4b2

2.1 Gerber files for the fabrication of the PCB

The Gerber files you need to manufacture the PCBs are on the download page

2.2 Fabrication instructions

  • Type of PCB: double sided
  • Dimensions of PCB: 126mm x 55mm
  • Base material: 1.6 mm FR4
  • Thickness of copper: 35 µm
  • Soldermask: yes
  • Silkscreen: only on top layer
  • Surface treatment: ENIG (Electroless Nickel Gold)

Automatic calibration and characterisation

1 Required components

To perform the automatic calibration and characterisation of the HVPS, you need some equipment: a high voltage probe (preferably a model capable of measuring dynamic signals), a NI-DAQ system, and an impedance matching circuit. The different components are described in details below.

1.1 High Voltage probe

You need a HV probe to transform the high voltage output of the HVPS into a low voltage signal that can be fed to an acquisition device. The characterisation routines integrated in the GUI give the possibility to characterize the switching speed or the voltage regulation speed and stability. If you want to perform these measurements, you need to be able to measure dynamic signals. Therefore, you need a HV probe that is capable of measuring AC signals. We use a 10kV 1:1000 50MHz PR-55 probe from B&K Precision, but there are many other possibilities.

PR-55 50 MHz oscilloscope probe

HV probes designed to be used with multimeters are suitable to perform the voltage calibration, but will not work for the other tests, because they require to measure voltage steps (i.e. the probe must have a large bandwidth).

1.2 NI-DAQ system

You need a NI-DAQ system to acquire the analogue voltage on a computer. We use a NI USB-6212 BNC, but any system will do, as long as they have at least one analogue input. The entry-level NI USB-6000 should work fine. You must be sure not to exceed the voltage rating of your DAQ system when you connect the probe to it. However, NI-DAQ systems usually accept input signals in the +/- 10 V range, and HV probe commonly have a 1:1000 attenuation. Given that the HVPS with the highest rating (5kV) will output 5000 V or less, the voltage at the DAQ input will be between 0 V and 5 V, i.e. well within specification.

NI USB-6212

1.3 Impedance matching circuit

The dynamic HV probes, such as the 50MHz PR-55 we use are designed to be connected to an oscilloscope with a 1 MOhm input impedance (and if you are using a multimeter probe, it is likely designed to be connected to a multimeter with a 10 MOhm input impedance). NI-DAQ systems have a an input impedance >10 GOhm. Connecting a HV probe directly to a NI-DAQ system will lead to erroneous readings. In addition, it is recommended that signals connected to a NI-DAQ system have a low source impedance, which is not the case with HV probes.

You need to use an impedance matching circuit as interface between the probe and the NI-DAQ. In its simplest form, the impedance matching circuit is just a 1 MOhm resistor placed in parallel with the probe.

Passive impedance matching circuit: a 1 MOhm resistor in parallel with the probe

2 High Voltage Probe calibration

2.1 Performing the probe calibration

High voltage probes have a defined attenuation ratio (most of the time 1:1000), so a calibration is not absolutely necessary. However, much better accuracy can be obtained by performing a probe calibration. To perform a probe calibration, you will need a precision HV power supply, i.e. a power supply with an output voltage that you trust as being accurate. We use a Stanford Research Systems PS350/5000V power supply for this purpose.

Stanford Research Systems PS350/5000V power supply

  • Connect your HV probe to the precision HV power supply, and to the impedance matching circuit. Connect the impedance matching circuit to the NI-DAQ.
  • For a set of voltages between 0 V and 5000 V (e.g. with steps of 100 V), set the HV power supply to the desired voltage value, and write down the low voltage value indicated by the NI-DAQ. NI provides tools to directly read a channel from a NI-DAQ connected to a computer so that you can read the analogue voltage. Alternatively, the HVPS interface provides the possibility to read the value of the high voltage probe from the configuration options (see screenshot). For this to work, there are two prerequisites: 1) The name of the NI-DAQ and the channel to read must be configured (see § 2.2 below), and a HVPS must be connected to the computer, or the interface main window won’t show up. The password to unlock the functions requiring the NI-DAQ is Bazinga!
  • Plot the HV voltage value from the HV power supply (y axis) as a function of the low voltage value displayed by the NI-DAQ (x axis).
  • Use curve fitting to find correction coefficients (see examples below)

The graph below shows the error between the voltage calculated from the probe reading using the 1:1000 factor of the probe (i.e. without custom calibration). The approximation is acceptable, but there is an appreciable error, and a non-negligible average offset.

Based on the above information, a linear fit with offset, of the form y=c1 x + c0 is fitted to the data to account for the offset and a non-perfect ratio of the probe (see graph below). The error is much smaller. However, the error is not random, but takes the shape of a parabola, due to a non-linear effect of unknown origin.

Consequently, we fit the curve with a generic 2nd order polynomial of the form y=c2 x^2 + c1 x + c0. The error for this fit is given below. The error is considerably smaller than for the linear correction and comprised within a 3 V band.

Error in V between actual voltage and voltage measured with the probe using a quadratic fit.

Given the previous observations, a generic 2nd order polynomial is recommended to calibrate your HV probe/impedance matching circuit/DAQ setup. The GUI interface integrates the possibility to have 2nd order polynomial to calibrate your probe. But by setting the right coefficient to 0, you can have a simple proportional calibration if you prefer. See the following section for how to enter your calibration coefficients so that your probe can be used for the automatic calibration.

2.2 Configuring the GUI to use the probe calibration

To keep the HVPS interface program as compact as possible, we have only included the components that are essential to run the program from a user point of view. This means that the LabVIEW components required to read data from a NI-DAQ system are not included, and the automatic calibration routines won’t work on a computer on which you install the interface, unless you also install NI-DAQmx, which is the package required to control NI-DAQ systems. You should have received a copy of NI-DAQmx with your hardware. Else, it can be downloaded from the NI website. You will also need the report generation toolkit to generate the excel file summarizing the results.

In the directory in which you have installed the HVPS interface, there is a folder named support. Open the file config.ini located in this folder. The first lines should look like the screenshot below:

The file allows you to enter calibration values for different probes (in case you have more than on HV probe, each with their own calibration. The probe name currently used by the programme is defined at the second line with:

  • probe=”xxx”

where xxx represents the name you want to give to your probe, in this example it is PR55. You must then have a section in the file defining the parameters c0, c1, and c2 for your probe xxx defined by using the name of your probe in brackets, and then the 3 coefficients, each on one line:

  • [XXX]
  • c0=aa.aaaa
  • c1=bb.bbbb
  • c2=cc.cccc

The values of the coefficient c0 to c2 represents a quadratic fit obtained on your data from §2.1:
y = c0 + c1 x + c2 x^2
If you don’t want to calibrate your probe and want to use the ratio (e.g. 1:1000) provided by the manufacturer you can enter c0=0, c1=1000, and c2=0. If you only want a linear correction with offset, keep c2=0, etc.

In the [NI-DAQ] section you must enter the name of your NI-DAQ system (you can find that out with NI-MAX for example), and the analogue input channel to which the signal is connected. Our NI USB-6212 is called Dexter (but it hasn’t killed anybody… yet), and the signal is connected to the analogue input channel 0, so we have:

  • [NI-DAQ]
  • name=”Dexter”
  • HVchan=”ai0″

Important: The program is reading a differential voltage from the probe. On the NI USB-6212, this is totally transparent, because it is equipped with BNC connectors. However, if you are using another unit that has screw terminals, you must connect the return signal to the input which is paired with the main signal. Refer to the manual of your NI-DAQ, but most likely, you have to add 8 to the main analogue input channel. For example, if you connect the main signal to ai0, you must connect the return signal (i.e. the ground of the impedance matching circuit) to ai8.

3 Performing the automatic calibration / characterisation

After having followed the instructions of section 2 above, it is time to calibrate and characterize your HVPS:

 

  • High Voltage enable switch (s2): off position
  • Connect the SHVPS to the computer (USB + 6VDC) and launch the HVPS interface
  • Connect the HV cables to the output of the HVPS.
  • Take your probe and connect the low voltage side to the input of your impedance matching circuit
  • Connect the end of the HV cables to the probe: black to the ground of the probe and red to the HV terminal. Ensure that the HV (red) contact is well insulated, doesn’t touch any equipment and can not be touched by someone.
  • Connect the output of the impedance matching circuit to the NI-DAQ, and the NI-DAQ to your computer.
  • Power on the impedance matching circuit
  • High Voltage enable switch: on position
  • Open the HVPS options dialog box (green square), and if necessary, enter the password (Bazinga!) in the password input field (red) (we give the password here. The intention is not to make this secure, but just to prevent the general user of the HVPS to inadvertently change its configuration)

You are now ready to perform the automatic calibration / characterisation

4 Measurement file

The results of each of the tests mentioned above are saved in an excel file located in the support folder of the application (usually C:\HVPS_interface\support). Here are a few important points regarding the measurement file:

  • The measurement file is named yymmdd_board_name_data.xls, with yymmdd the date at which the file was initially created.
  • At the end of each measurement, the data is saved in the measurement file.
    • If no excel file with the name of the board being tested exists in the support folder, a new file will be created and the acquired data added to the file.
    • If a measurement file with the name of the board (irrespective of the date yymmdd) is present in the support directory, the new data will be added to this already existing file.
    • In this case, and if the measurement being done has already been done previously, the older measurement will be overwritten by the newly acquired data.
  • The first tab (sheet) in the excel document summarizes the test which are included in the file, so that the user can see at once what are the file contents.
  • The correct way to perform measurements is the following:
    • Perform all the tests that you need to characterize a board (typically, and especially if this is a newly assembled board, all of them)
    • Move the excel file from the support directory to a location where you archive all the measurements for future reference. It is important at this stage to move (and not copy) the file, so that the support directory doesn’t contain a file with the name of the HVPS anymore.
    • If at a later stage, the same HVPS is again characterized, then a new file will be created (instead of overwriting previous data, which would happen in case the first file remains in the support folder)
  • The files are generated based on an Excel template (template.xltx). The template must not be open in excel when measurements are made, or the report generation will fail. And logically, the template must not be deleted from the support directory.

 

Low voltage testing procedure of SHVPS board

The following testing procedure should be printed and marked for debugging and record keeping.

Name of testing agent:

Date:

Model (kV):

Board Name*:

I2C Address*:

*Assign a name and a I2C address to your board. The name and address will be stored at a later stage in the micro-controller. The name helps differentiate different HVPSs, and because they all have their own personality, and maximal voltage, we like to give them a distinctive name. The I2C address is used if you want to assemble several HVPS into a multi-channel high-voltage power supply (MHVPS). Valid addresses are between 10 and 127.

  1. Check all the resistor values. Place a tick in the box if the marking on the resistor matches the value below.
    ☐ R1 = 27R0
    ☐ R2 = 1500
    ☐ R3 = 1001
    ☐ R4 = 27R0
    ☐ R5 = 1001
    ☐ R7 = 1001
    ☐ R8 = 1500
    ☐ R9 = 9532 (5kV model)
    ☐ R9 = 8062 (3kV model)
    ☐ R9 = 1203 (2kV model)
    ☐ R9 = 8872 (1.2kV model)
    ☐ R9 = 2153 (500V model)
    ☐ R10 = 1001
    ☐ R11 = 1002
  2. Check the polarity of the components below. Place a tick in the box if the polarity matches the polarity on the PCB overlay.
    ☐ D1
    ☐ D2
    ☐ D3
    ☐ C3
    ☐ Q1
    ☐ Q2
    ☐ OC1
    ☐ OC2
  3. Measure the resistance between the 5V rail and GND.
    How to conduct test: Use the rail board to make a connection to the 5V and ground rails using the 10-pins connector and measure the resistance with a multimeter. (If you need to build your own rail board, solder a red wire to pin 2 (5V) and a black wire to pin 4 (GND), as shown on picture below.)

    Purpose of test: To determine if there are any shorts between the power rails before applying power.
    Resistance between red and black wire (Jumper h5V should be in the on position at this stage): 

    ☐ Resistance is approximately 1.1kΩ
  4. Measure the output of the 5V regulator.
    How to conduct test:

    *Leave the rail board connected for this test*
    a) Place the jumper h5v in the OFF position
    b) Plug in the 6V adapter.
    Order code: Farnell 1971788
    Part number: SW4305
    Description: POWERPAX  SW4305  AC/DC Power Supply, Switch Flyback, Fixed, 1 Output, 90 VAC, 264 VAC, 6 W, 6 V
    The product above is for European sockets. If you need a different power supply for your country, be sure it has the same voltage output, and connector (2.5mm x 5.5mm).

    c) Measure the voltage of the regulator relative to ground. The easiest way to do this is to use the rail board from the last step to connect to ground and to probe the large tab of Reg1 with a multimeter probe. Record the voltage below.

    Purpose of test: To determine if the regulator is functioning correctly without the remainder of the circuit connected.
    Voltage with jumper h5v in the OFF position:

    ☐ Voltage is approximately 5V
  5. Test if the circuit has power.
    How to conduct test:

    *Leave the rail board and the adapter connected for this test*
    a) Place the jumper h5v in the ON position
    b) Observe D1
    c) If LED D1 glows green, place a tick the check box and continue. If not, remove the jumper and investigate for a cause.

    Purpose of test: To determine if there are any components which are consuming too much power due to assembly errors or faulty components.
    ☐ D1 glows green
  6. Test the power pin on the microcontroller header and the HV indicator LED
    How to conduct test:

    *Leave the rail board and the adapter connected for this test. Leave the power jumper in the ON position*
    a) Insert the dummy microcontroller. The dummy microncontroller is a small board which imitates the functions of the arduino micro.

    b) Ensure that the switch on the dummy microcontroller is in the ‘D3 test’ position.
    c) Observe the LED on the dummy microcontroller. If the LED glows orange, place a tick in the box below. If not, remove the power jumper (h5v) and check for a cause.
    d) Observe LED D3. If LED D3 glows red, place a tick in the box below. If not, remove the power jumper (h5v) and check the polarity of LED D3.

    Purpose of test:
    Step c) tests whether the power pins on the microcontroller are connected to power. Step d) tests if the HV indicator LED is functional.
    ☐ The LED on the dummy microcontroller glows orange
    ☐ LED D3 glows red when the switch is in the ‘D3 test’ position
  7. Check if the high frequency switching circuit is functioning correctly
    How to conduct test:
    *Leave the rail board, adapter, and dummy microcontroller connected for this test. Leave the power jumper in the ON position*
    a) Place a jumper on H2 in the ‘Button’ position.
    b) Connect the COM port of the multimeter to the GND wire of the rail board.
    c) Using a probe measure the voltage of the via close to R4. Record the voltage when S1 is depressed and when pressed.

    Purpose of test: This test measures the output from Q1. The voltage must toggle from rail to rail to turn the infrared LEDs on and off.
    Voltage on via close to R4 when S1 is depressed:


    ☐ voltage on via is ~5V when button is depressed
    Voltage on via close to R4 when S1 is pressed:

    ☐ voltage on via is ~0V when button is pressed
  8. Check all the components powering the EMCO DC-DC converter
    How to conduct test: 
    *Leave the rail board, adapter, dummy microcontroller, and multimeter connected for this test. The power jumper must be in the ON position*
    a) Place the safety switch S2 is in the On position (indicated on the board with a small ‘1’ to the right of the switch)
    b) Ensure that the COM port of the multimeter is still connected to the GND wire of the rail board.
    c) Place the switch on the dummy microcontroller into the ‘EMCO test’ position
    d) Using a probe measure the voltage on pin pair 2-5 (see picture) and record the value below.
    e) Place the switch on the dummy microcontroller into the ‘D3 test’ position
    f) Using a probe measure the voltage on pin pair 2-5 (see picture) and record the value below.

    Purpose of test: To test if the circuit providing power to the EMCO is able to provide 5V.
    Voltage on pin pair 2-5 when switch is in ‘EMCO test’ position:

    ☐ voltage on pin pair 2-5 is ~5V when the switch is in EMCO test position
    Voltage on pin pair 2-5 when switch is in ‘D3 test’ position:

    ☐ voltage on pin pair 2-5 is drifting towards zero when the switch is in D3 test position

If your HVPS has passed all the low voltage tests above (all check boxes ticked), you can continue with the soldering of the high voltage components (section 4 of the assembly page).

Full Enclosure

The full enclosure is a complete box that protects the SHVPS and prevents users from touching the high voltage components. The important functions (buttons and LEDs) are placed on a front panel. In the current versions, the onboard LEDs are used, but transparent light pipes guide the light to the front panel. The two buttons (High Voltage enable and push button) are mounted on the panel. Consequently, in step 18 of the assembly instructions, it is necessary to solder header hS1 and hS2, but headers hD1 and hD3 are not required.

Alternatively, you can also assemble a minimal enclosure which is simpler and easier to assemble. It only covers the HV side of the circuit, and uses the onboard switches and LEDs.

We use a Laser Engraver Trotec Speedy 300 to cut the parts required for the enclosure, and we have prepared files ready to be cut. We also have the Solidworks 3D files, so you can use whatever method you want to cut the parts or modify the enclosure to fit your needs.

Download the Solidworks files (Solidworks 2015)

1. Cutting / Preparing the parts

The enclosure is made of 3 different materials/parts

1.1 Enclosure Body

We use a 3 mm thick opaque PMMA for the main body of the enclosure. The file full_opaque_box.svg contains all of the parts that need to be cut to assemble the main body. You need a plate of at least 150 mm x 280 mm to cut all the parts.

1.2 Front Panel

We use an engravable plastic TRANSPLY-HD with a black body and a white front layer. We  use the 1.5mm-thick plates. You can use any other thickness value, but the length of the light pipe (see below) must be adapted accordingly. The file front_panel_model.svg can be used as a base for the front panel.

The black filled shapes are engraved by the laser. The red and blue lines are the cut lines, matching the one on the part “Top”. We recommend that you indicate the name of the HVPS and the voltage rating (Edit the string that says “Name” X kV by the actual name and the voltage rating of your HVPS.) You can use the space below the name to add an image in relation with the name of your HVPS, and there is space for a logo on the bottom left. See illustrative example at the top of the page…

A Laser works very well to engrave the panel, but is not optimal to cut the openings and external shape (ABS is not easy to cut with a Laser, because it melts). We suggest you try one of the following approaches:

  1. Start by cutting the openings before removing the protective cover on the top. The bits of molten ABS will land on the protective cover and will not stain the panel. Then remove the protective cover and proceed with the engraving step. The disadvantage with this method is that you need to precisely position the panel after cutting it so that the engraving match the geometry. But a very precise alignment is not required anyway.
  2. Start by removing the protective cover and replace it by masking tape. You can then do the three operation in one go without moving anything and in the logical order (engrave, cut red, cur blue). You must adapt the engraving parameters to go through the masking tape too. Masking tape burns without melting. This is the reason why we replace the plastic cover sheet with masking tape. Finish by removing the masking tape that will have caught the projections creating during the cutting step.

1.3 Light Pipes

The file LED_pipe.svg defines a light pipe used to guide the light from the onboard LED to the front panel. You should be cut two light pipes into a 3mm-thick transparent material (we use PMMA). You need to cut two light pipes (power LED and HV LED). The file as designed is for a front panel (see previous §) thickness of 1.5 mm. If you use another thickness for the front panel, you should adapt the length of the light pipe. It is a good idea to sand the top of the light pipe to diffuse the light of the LED on the front panel

2 Assembling the parts

  1. Using glue for plastics (we use dichloromethane), assemble together the following parts (see picture below): base, side_hv, side_hv_cache, side_jack and back.

    Base: Place the larger 3 openings on your left.
    Back: The slit must be at the bottom right.
    Side_jack: On the right. The straight side (without slots) towards the front.
    Side_hv: On the inside left. The straight side (without slots) towards the front.
    Side_hv_cache: On the outside left. The straight side (without slots) towards the front.
  2. You can slide a HVPS to check that everything is correctly positioned.
  3. Place M2 threaded metallic inserts (Tappex Multisert – Single Thickness Head – 071M2) in the parts holder and holder2.
    Note: You can replace the inserts by a threaded hole. In that case, you must modify the diameter of the holes on these parts to 1.5mm prior to cutting the parts.
  4. Glue the following parts (see picture below): top, holder and the two holder2.
    Place top so the rectangular opening is in front of you, and the 2×3 openings on your left (see image). holder goes on the left, and the two holder2 on the right. The flanges from the inserts (not shown on the picture) should be located on the inside.

  5. Place double sided tape (or glue) on the top of the front panel.
    The two large openings for the two buttons, as well as the 2 small square openings for the diode lightpipes must remain free from tape.
  6. Place the engraved front panel on top of the tape-covered top part.
    Carefully align the two parts. It may help to first place the large switch in the engravable panel, and use it as a guide. The two lightpipes can also be used to add guiding posts to perfectly align the two pieces together. Apply pressure to fix the two parts together.
  7. If not already done so at the previous step, insert the switch in the square opening.
    Order code: Farnell 4710368
    Part number: PRASA1-16F-BB0BW
    Description: TE CONNECTIVITY / ALCOSWITCH  PRASA1-16F-BB0BW  Rocker Switch, Non Illuminated, SPST, On-Off, Black, Panel, 16 A
  8. Insert the push-button in the round opening.
    Order code: Farnell 1634622
    Part number: R13-502A-05-B
    Description: MULTICOMP  R13-502A-05-B  Pushbutton Switch, Off-(On), SPST, 125 V, 3 A, Solder
  9. Insert the two light pipes in the small square openings and glue them in place from the backside.
  10. Solder wires to the the switch and push button.
    The wires for the switch should be 110 mm long.
    The wires for the push button should be 60 mm long.
    Take a wire to board connector and cut two units of two pins. Solder one unit at the extremity of each of the cables.
    Order code: Farnell 9729100
    Part number: SL 3.25.36G
    Description: FISCHER ELEKTRONIK  SL 3.25.36G  Wire-To-Board Connector, Right Angle, SL Series, 36 Contacts, Plug, 2.54 mm, Through Hole, 1 Rows
    The picture below illustrates steps 7-10
  11. Connect the wire from the push button to header hS1. Cut the wire-to-board connector of the switch to separate the two contacts, and insert the contacts into header hS2.

    The wire from the switch should go along the Arduino and between the edge of the Arduino and the power jack in the back, as shown on the image above. The two contacts should be inserted sideways into header hS2, as shown in picture below so that the wire doesn’t cover the onboard LED D1, or else you won’t be able to place the cover with the light pipe (see image below).
  12. Place the side panel (part front-removable).
    The onboard switch S2 must be in the 0 position. There is a notch in the front-removable part that prevents you from placing the part when the switch is not in the correct position.
  13. Place the front panel in place, and lock it in place with 4 plastic M2x10 screws.

High voltage testing procedure of SHVPS board

 

The testing procedure should be printed, marked and added to the other testing documents.
Report the name and I2C address from the low-voltage test sheet.

Name of testing agent:_______________________________________________________

Date:___________________________________________________________________

Board Name:______________________________________________________________

I2c Address:_______________________________________________________________

Test of the micro-controller

  1. Take a Arduino micro, but do not install it on the HVPS PCB.
  2. Open the Arduino IDE (you must have the Arduino IDE installed, as well as the required drivers for the serial communication. Refer to this page for more information)
  3. Program the Arduino with the Send_PWM program.
  4. In Arduino GUI, open the Serial Monitor.
  5. Set the termination character to “Carriage return” and the transmission speed to “115200” in the 2 dropdown lists.
    serial_monitor
  6. Check that the the onboard LED (green) is fully on
    ☐ Onboard LED is on
    uc_test_steps6_8
  7. In the serial monitor, enter 0 and press enter. The green LED should turn off, and the terminal should indicate:
    PWM set point: 0
    ADC read XXX
    (the value of XXX is not important at this stage)
    ☐ Expected values are displayed on the terminal
    ☐ Onboard LED is off
    uc_test_step7
  8. In the serial monitor, enter 1023 and press enter. The green LED’s intensity should be at 100%,  and the terminal should indicate:
    PWM set point: 1023
    ADC read XXX
    (the value of XXX is not important at this stage)
    ☐ Expected values are displayed on the terminal
    ☐ Onboard LED is on
    uc_test_steps6_8
  9. Close serial monitor, and unplug the USB cable from the Arduino.

Testing the High Voltage

Be Careful when testing the high voltage part of the circuit, as the board is not yet in a protective enclosure. High voltage will be present at the output and on some of the components during the testing of steps 6 and 7. It is important not to touch any part of the SHVPS during this test, and to place the PCB on a well-insulated surface.

  1. Insert the micro-controller into socket UC1 of the HVPS board, with the USB connector aligned with the PCB overlay
    hv_test_step1
  2. Be sure that the HV enable switch (S2) is in the 0 position
    hv_test_step2
  3. Plug the USB cable to the microcontroller
  4. Open the serial monitor in the Arduino interface (the end character and speed settings should be CR/115200, see above)
  5. Place HV enable switch (S2) on 1
  6. On serial monitor, enter 0 and press enter. Write the reading from the ADC:
    ADC Read: ___________________
    ☐ ADC Read is higher than 850 and smaller than 1023
  7. On serial monitor, enter 500 and press enter. Write the reading from the ADC:
    ADC Read: ___________________
    ☐ ADC Read is higher than 200 and smaller than 1023
  8. On serial monitor, enter 1023 and press enter. Write the reading from the ADC:
    ADC Read: ___________________
    ☐ ADC Read is smaller than 10. If not, try step 8 once again.
  9. Close serial monitor
  10. Place HV enable switch (s2) on 0
  11. Remove USB cable

Next Steps

  1. Place the jumper of header H2 in the central (onboard) position if you want to use the board with the GUI. If you want to force the use of the push button or the external pin as switching source, you can place the jumper on the appropriate position
  2. If the board is assembled at EPFL-LMTS, Fill columns A to H in the Excel database of assembled boards (HVPS-dev\Slave\ Assembled_SHVPS_database.xlsx). Names and address are not yet stored in the micro-controller, this is normal.
  3. Place a sticker at the back of the PCB indicating: Board name, maximal voltage, and I2C address. Name and address will be stored at a later stage in the micro-controller. Use the name and address you have defined at the top of this test sheet.
  4. Continue with the calibration of the board, and the fabrication of the enclosure.

Assembly procedure for SHVPS v4b2

1 Pre-assembly Procedure

  • Take a PCB and clean it with isopropyl alcohol. Wear gloves during assembly.

2 Soldering of Low Voltage Components

  1. Solder dual MOSFETs Q1 and Q2. Make sure that the notch on the chip is aligned with the notch on the PCB overlay.
    Order code: Farnell 1498963
    Part number: FDS8858CZ
    Description: Dual MOSFET, N and P Channel, 8.6 A, 30 V, 17 mohm, 10 V, 1.6 V
    step_1
  2. Solder capacitors C1 and C2. Polarity is not important.
    Order code: Farnell 2426964
    Part number: GRM319R61C106KE15D
    Description: SMD Multilayer Ceramic Capacitor, 1206 [3216 Metric], 10 µF, 16 V, ± 10%
    step_2
  3. Solder capacitor C4. Polarity is not important.
    Order code: Farnell 1833891
    Part number: 12063C334KAT2A
    Description: SMD Multilayer Ceramic Capacitor, 1206 [3216 Metric], 0.33 µF, 25 V, ± 10%
    step_3
  4. Solder the resistors R1 and R4. Polarity is not important.
    Order code: Farnell 2332118
    Part number: CRGH1206F27R
    Description: SMD Chip Resistor, Thick Film, 27 ohm, 200 V, 1206 [3216 Metric], 500 mW, ± 1%
    step_4
  5. Solder resistors R2 and R8. Polarity is not important. Note that R8 is vertical; do not solder it on the pad D3.
    Order code: Farnell 1795172
    Part number: CR1206-FX-1500ELF
    Description: SMD Chip Resistor, Thick Film, 150R, 1%, 0.25W, 1206
    step_5
  6. Solder resistors R3, R5, R7, and R10.
    Order code: Farnell 2307294
    Part number: ERJ8ENF1001V
    Description: SMD Chip Resistor, Thick Film, 1 kohm, 200 V, 1206 [3216 Metric], 250 mW, ± 1%
    step_6
  7. Solder resistor R11.
    Order code: Farnell 1632523
    Part number: MC1206S4F1002T5E
    Description: SMD Chip Resistor, Thick Film, 10K, 1%, 0.25W, 1206
  8. Solder resistor R9.
    The value of R9 depends on the output voltage of the HVPS. Please select the appropriate value below.
    For the 5kV model:
    Order code: Farnell 2327394
    Part number: ERJP08F9532V
    Description: SMD Chip Resistor, Thick Film, 95.3 kohm, 500 V, 1206 [3216 Metric], 660 mW, ± 1%, ERJP08 Series
    For the 3kV model:
    Order code: Digikey P80.6KFCT-ND
    Part number: ERJ-8ENF8062V
    Description: RES SMD 80.6K OHM 1% 1/4W 1206
    For the 2kV model:
    Order code: Digikey P120KFCT-ND
    Part number: ERJ-8ENF1203V
    Description: RES SMD 120K OHM 1% 1/4W 1206
    For the 1.2kV model:
    Order code: Farnell 2327378
    Part number: ERJP08F8872V
    Description: PANASONIC ELECTRONIC COMPONENTS  ERJP08F8872V  SMD Chip Resistor, Thick Film, 88.7 kohm, 500 V, 1206 [3216 Metric], 660 mW, ± 1%, ERJP08 Series
    For the 500V model:
    Order code: Farnell 2327103
    Part number: ERJP08F2153V
    Description: PANASONIC ELECTRONIC COMPONENTS  ERJP08F2153V  SMD Chip Resistor, Thick Film, 215 kohm, 500 V, 1206 [3216 Metric], 660 mW, ± 1%, ERJP08 Series
    More details on the design of the voltage divider and the resistance values.
    step_8
  9. Solder D1 (Green). Note the polarity! The green markings on top of the LED should face the thick line on the PCB overlay.
    Order code: Farnell 2062262
    Part number: SML-LX1206GW-TR
    Description: LED, QuasarBrite, Green, SMD, 3.2mm x 1.6mm, 20 mA, 2.2 V, 565 nm
    step_9
  10. Solder D3 (Red). Note the polarity! The green markings on top of the LED should face the thick line on the PCB overlay.
    Order code: Farnell 2062231
    Part number: SML-LX1206IW-TR
    Description: LED, QuasarBrite, Red, SMD, 3.2mm x 1.6mm, 20 mA, 2 V, 635 nm
    step_10
  11. Solder Reg1.
    Order code: Farnell 1825292
    Part number: AP1117E50G-13
    Description: Fixed LDO Voltage Regulator, 6.4V to 18V, 1.2V Dropout, 5Vout, 1Aout, SOT-223-3
    step_11
  12. Solder D2. Note the polarity! The line on the diode should match the line on the PCB overlay.
    Order code: Distrelec 170-15-894 (old order code: 60 57 24)
    Part number: STPS2L40U
    Description: Schottky diode, 2 A, 40 V, DO-214AA=SMB
    step_12
  13. Solder S1. Polarity is not important
    Order code: Farnell 3121185
    Part number: B3FS-1050
    Description: Tactile Switch, Non Illuminated, 24 V, 50 mA, 0.98 N, Solder, B3FS Series
    step_13
  14. Solder C3. Note the polarity! The line on the diode should match the marking on the PCB overlay.
    Order code: Farnell 2473573 (old order code 1793889)
    Part number: T491D227K016AT
    Description: Surface Mount Tantalum Capacitor, 220 µF, 16 V, T491 Series, ± 10%, 2917 [7343 Metric]
    step_14
  15. Solder S2.
    Order code: Farnell 674357
    Part number: 09-10290-01
    Description: Slide Switch, SPDT, Through Hole, 500 mA
    step_15
  16. Solder edge connector K56GVFTRDC. The edge connector is supplied in long strips. Using a pair of pliers break off a row of 10 pins.
    Order code: Farnell 9729100
    Part number: SL 3.25.36G
    Description: Wire-To-Board Connector, Right Angle, SL Series, 36 Contacts, Plug, 2.54 mm, Through Hole, 1 Rows
    step_16
  17. Solder h5V. Polarity is not important.
    Order code: Distrelec 300-24-522 (old order code: Farnell 1022245)
    Part number: 61300311121
    Description: Pin header 3P Single row / straight / without shroud
    step_17
  18. Solder hD1, hD3, hS1, hS2 if you intend to have components D1, D3, S1, S2 panel mounted. Polarity for these headers is not important.
    Order code: Farnell 1668221
    Part number: SSA-102-S-G
    Description: SAMTEC  SSA-102-S-G  Board-To-Board Connector, SSA Series, 2 Contacts, Receptacle, 2.54 mm, Through Hole, 1 Rows
    If you intend to place the board in the minimalistic enclosure, soldering these headers is not necessary. If you intend to place the board in the full enclosure, only headers hS1 and hS2 are necessary.
    step_18
  19. Solder H2. Polarity is not important.
    Order code: Farnell 1022230
    Part number: M20-9980345
    Description: Board-To-Board Connector, Vertical, M20 Series, 6 Contacts, Header, 2.54 mm, Through Hole, 2 Rows
    step_19
  20. Solder J1. 
    Order code: Farnell 1200151
    Part number: NEB/J 25 R
    Description: DC Power Connector, Jack, 1 A, 2.35 mm, Through Hole Mount
    step_20
  21. Solder header sockets for microcontroller. The header sockets are supplied in long strips. Score the plastic with a craft knife and break off 17 contacts with a pair of pliers. Clean up the rough edge with the craft knife or sandpaper.
    Order code:  Farnell 2396216
    Part number: 929974-01-36
    Description: Board-To-Board Connector, 929 Series, 36 Contacts, Receptacle, 2.54 mm, Through Hole, 1 Rows
    step_21
  22. Solder L1. Polarity is not important.
    Order code: Distrelec 158-00-420 (old order code: 335529)
    Part number: ELC16B821L
    Description: Inductor, radial 820 uH 0.88 A ±10%, Panasonic Automotive & Industrial Systems
    step_22
  23. Prepare optocouplers OC1 and OC2. Please follow the instructions below:
    Bending of the leads:
    Bend the leads as shown in the series of images below.
    bending_oc
    Mark pin 1 (before painting):
    Bend the tip of pin 1 so that it can be identified after painting the optocoupler.
    Painting of the optocoupler:
    The optocoupler is painted to prevent inteference from neighbouring optocouplers and IR light which is present in the environment. Tipp-Ex is used because it creates a relatively good barrier to IR light and is easy to apply. Simply paint the plastic body of the optocoupler with a single layer of Tipp-Ex and let it dry. It is best to do it rapidly and in single strokes. Making multiple passes results in a sticky mess which is very unsightly.
    Mark pin 1 (after painting):
    Use a permanent pen to mark pin 1 with a dot next to the pin.
    METADATA-START
    Order code: MPI Distribution AG OC100G
    Part number: OC100G
    Description: HV Opto-Coupler 10 kV
  24. Solder optocouplers OC1 and OC2. Make sure that the polarity is correct.
    step_24
    (unlike what is shown on the picture above, the EMCO DC/DC converter and resistor R6 are not yet soldered)
  25. Place the jumper on h5V in the ON position, and the jumper h2 in the Button position.
    Order code: Farnell 9728961
    Part number: CAB 4 GR
    Description: Jumper (Busbar), Jumper, 0.6 to 0.64mm Wire Wrap Pins and 0.6 to 0.7mm Dia, 2 Ways, 2.54 mm
    step_24
  26. You are ready to test the low voltage part of your HVPS

3 Testing procedure of the Low-voltage part of the HVPS

Before assembling the High-voltage components, go through the low-voltage testing procedure and ensure that the circuit is working properly. Only proceed with the assembly of the HV components if all the low voltage tests have passed.

4 Soldering of High Voltage Components

  1. Solder R6. Do not fully insert this resistor. Insert it so that 2mm of the leads can be seen above the top surface of the PCB.
    The value of R6 depends on the output voltage of the HVPS. Please select the appropriate value below.
    For the 5kV model:
    Order code: Farnell 1550763
    Part number: SM102031006FE
    Description: OHMITE  SM102031006FE  Through Hole Resistor, Slim-Mox, 100 Mohm, 5 kV, Radial Leaded, 1 W, ± 1%, Slim-Mox Series
    For the 3kV model:
    Order code: Digikey SM102035005FE-ND
    Part number: SM102035005FE
    Description: RES 50M OHM 1W 1% RADIAL
    For the 2kV model:
    Order code: Digikey SM102035005FE-ND
    Part number: SM102035005FE
    Description: RES 50M OHM 1W 1% RADIAL
    For the 1.2kV model:
    Order code:  Digikey 22MGBCT-ND
    Part number: HHV-50FR-52-22M
    Description: RES 22M OHM 1/2W 1% AXIAL
    For the 500V model:
    Order code:  Digikey 22MGBCT-ND
    Part number: HHV-50FR-52-22M 
    Description: RES 22M OHM 1/2W 1% AXIAL
    More details on the design of the voltage divider and the resistance values.
    hv_step_1
  2. Solder EMCO1
    EMCO1 is the DC/DC converter of the HVPS, and its voltage rating defines the maximal output voltage of the HVPS. Use the following values:
    For the 5kV model:
    Order code: EMCO/Condatas A50P-5
    Part number: A50P-5
    Description: 5 kV A Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 3kV model:
    Order code: EMCO/Condatas A30P-5
    Part number: A30P-5
    Description: 3 kV A Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 2kV model:
    Order code: EMCO/Condatas A20P-5
    Part number: A20P-5
    Description: 2 kV A Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 1.2kV model:
    Order code: EMCO/Condatas A12P-5
    Part number: A12P-5
    Description: 1.2 kV A Series Isolated, Proportional DC To HV DC Converter 5V input
    For the 500V model:
    Order code: EMCO/Condatas A05P-5
    Part number: A05P-5
    Description: 500 V A Series Isolated, Proportional DC To HV DC Converter 5V input
    hv_step_2
  3. Solder the red HV socket H3
    Order code: Distrelec 140-21-352
    Part number: 0040.1102
    Description: Socket ø 2 mm red, 0040.1102, Schurter
    hv_step_3
  4. Solder the black HV socket H3
    Order code: Distrelec 140-21-351
    Part number: 0040.1101
    Description: Socket ø 2 mm black, 0040.1101, Schurter
    hv_step_4

5 Testing procedure of the High-voltage part of the HVPS

Once you have finished the assembly of the high-voltage components, you are ready to test the high-voltage portion of the circuit. Follow these instructions.

6 HV cables

  1. Cut the appropriate length of HV electrical cable.
    Red wire:
    Order code: Digikey W2722R-100-ND
    Part number: 2722/22 R/C
    Description: TEST LEAD 22AWG 5000V RED 100′
    Black wire:
    Order code: Digikey W2722B-100-ND
    Part number: 2722/22 B/C
    Description: TEST LEAD 22AWG 5000V BLACK 100′
  2. Manually enlarge the opening of the 2mm banana plug cover with a 3mm drill bit so it can fit over the HV cable.
    Red banana plug:
    Order code: Farnell 1699020
    Part number: 25.205.1
    Description: MULTICOMP  25.205.1  BANANA PLUG, 10A, 2MM, CABLE, RED
    Black banana plug:
    Order code: Farnell 1699021
    Part number: 25.205.2
    Description: MULTICOMP  25.205.2  BANANA PLUG, 10A, 2MM, FREE, BLACK
  3. Solder the banana plugs to the wires and install the protective covers
  4. At the other extremity of the cable, install the connector you need for your application. We use Alligator clips as versatile connectors.
    Red Clip:
    Order code: Digikey 36-5034-ND
    Part number: 5034
    Description: ALLIGATOR CLIP INSULATED RED
    Black Clip:
    Order code: Digikey 36-5035-ND
    Part number: 5035
    Description: ALLIGATOR CLIP INSULATED BLACK

7 Next steps

Once you have finished assembling and testing (Low voltage testing, High voltage testing) your HVPS, you should place in in a safe enclosure and proceed with configuration/calibration.