Warning

OhmPi is a participative project open to all, it requires skills in electronics and to respect the safety rules. OhmPi must be assembled in a professional context and by people competent in electronics. The OhmPi team cannot be held responsible for any material or human damage which would be associated with the use or the assembly of OHMPI. The OhmPi team cannot be held responsible if the equipment does not work after assembly.

Measurement board 2024.0.2

The 2024.0.2 measurement board has been developed to replace the 2023.0.1 measurement board. It offers superior performance compared to its predecessor. The current measurement component has not evolved and presents no major differences. However, the major upgrade is the Mikroe-2C Isolator Click module (’https://www.mikroe.com/i2c-isolator-click’) . Specifically, it provides electrical isolation for the Vmn measurement set. This isolation allows for injection voltages (Vab) up to 200V

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Assembly of the measurement board

Schematics

Overview of the measurement board.

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Schematic of the power supply.

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Schematic of the DPS (digital power source) power supply.

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Schematic of the Vmn signal conditioning.

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Schematic of the current injection and measurement.

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Schematic of the human-machine interface.

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Required components

List of components

Component

Quantity

Cost per unit

Mouser ref

Manufacturer

Manufacturer reference

Description

Web link

Total cost EUR excl.VAT

100 kOhm resistor

13

0.223

594-5063JD100K0FT

MBA02040C1003FRP00

Vishay

Metal Film Resistors - Through Hole .4watt 100Kohms 1% 1/8watt body size

https://eu.mouser.com/ProductDetail/Vishay-Beyschlag/MBA02040C1003FRP00?qs=mzRxyRlhVdt9crF7Zyf%2F5Q%3D%3D

2.899

330 Ohms resistor

4

0.307

279-CFR100J330R

CFR100J330R

TE Connectivity

Carbon Film Resistors - Through Hole 330Ohm 1W 500PPM

https://eu.mouser.com/ProductDetail/TE-Connectivity-Holsworthy/CFR100J330R?qs=DDevMFOh4ssVKnglsGY0HA%3D%3D

1.228

4.7 kOhms resistor

4

0.307

603-CFR-25JB-52-4K7

CFR-25JB-52-4K7

YAGEO

Carbon Film Resistors - Through Hole 1/4W 4.7K Ohm 5%

https://eu.mouser.com/ProductDetail/TE-Connectivity-Holsworthy/CFR100J330R?qs=DDevMFOh4ssVKnglsGY0HA%3D%3D

1.228

2 ohms shunt resistor

1

1.33

588-WNC2R0FET

WNC2R0FET

Ohmite

Wirewound Resistors - Through Hole 2W 2 ohms 1%

https://eu.mouser.com/ProductDetail/Ohmite/WNC2R0FET?qs=CDPnWzNfzJb5BMolBZTI%252Bw%3D%3D

1.33

50V 1A general purpose rectifier diode DO-41

6

0.214

637-1N4001

1N4001

Diotec

Semiconductor Rectifiers Diode DO-41 50V 1A

https://eu.mouser.com/ProductDetail/Diotec-Semiconductor/1N4001?qs=OlC7AqGiEDlll8NA510wmA%3D%3D

1.284

cree LED

4

0.279

941-C503BGANCD0E0781

C503B-GAN-CD0E0781

Cree LED

Standard LEDs - Through Hole Green LED 527nm 5-mmRound 32900-64600mcd

https://eu.mouser.com/ProductDetail/Cree-LED/C503B-GAN-CD0E0781?qs=7D1LtPJG0i1J7Dm%252B%252B5IGZw%3D%3D

1.116

50V 0.2 A small signal schottky diode DO-35

2

0.437

771-BAT86113

BAT86 113

Nexperia

Schottky Diodes & Rectifiers BAT86/SOD68/DO-34

https://eu.mouser.com/ProductDetail/Nexperia/BAT86113?qs=me8TqzrmIYX1ahcmZsx1tg%3D%3D

0.874

OP27E (single ultra offset 8DIP)

4

9.53

584-OP27EPZ

OP27EPZ

Analog Devices Inc.

Precision Amplifiers LOW-NOISE PRECISION OP AMP

https://eu.mouser.com/ProductDetail/Analog-Devices/OP27EPZ?qs=WIvQP4zGangDp3uWiH2URA%3D%3D

38.12

MCP23008 (GPIO expander)

2

1.89

485-593

593

Adafruit

Adafruit Accessories MCP23008 - i2c 8 input/output port expander

https://eu.mouser.com/ProductDetail/Adafruit/593?qs=GURawfaeGuAf08zux7w%2FuQ%3D%3D

3.78

ADS1115 adafruit board (pack of 3)

2

14.9

485-1085

1085

Adafruit

Data Conversion IC Development Tools ADS1115 16-Bit ADC - 4 Channel with Programmable Gain Amplifier

https://www.amazon.fr/AZDelivery-ADS1115-Parent-3X/dp/B07QHWLTTS/ref=sr_1_5?__mk_fr_FR=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=18WHXZ3E0NUR5&keywords=ads1115&qid=1702140215&sprefix=ads1115%2Caps%2C117&sr=8-5

14.99

2.5V precision voltage reference

1

6.12

584-REF03GPZ

REF03GPZ

Analog Devices Inc.

Voltage References PRECISION LOW-COST 2.5V R

https://eu.mouser.com/ProductDetail/Analog-Devices/REF03GPZ?qs=WIvQP4zGangjpDFoUwu1Bw%3D%3D

6.12

DG411DJ analog switch

1

2.23

781-DG411DJ-E3

DG411DJ-E3

Vishay

Analog Switch ICs HIGH SPEED DG411 DIP-16

https://eu.mouser.com/ProductDetail/Vishay-Semiconductors/DG411DJ-E3?qs=xkjjIvogybzZNZq%252BuWCW1Q%3D%3D

2.23

unpolar capacitor 100nF

12

0.214

594-K104K15X7RF5UL2

K104K15X7RF5UL2

Vishay

Multilayer Ceramic Capacitors MLCC - Leaded K 50V 100NF +/- 10 % X7R AMMO E3

https://eu.mouser.com/ProductDetail/Vishay-BC-Components/K104K15X7RF5UL2?qs=rLgk8CAOBHbCqsnkGO2HJA%3D%3D

2.568

polarized capacitor 10uF

10

0.27

667-EEU-EB1J100S

EEU-EB1J100S

Panasonic

Aluminum Electrolytic Capacitors - Radial Leaded 10uF 63volts AEC-Q200

https://eu.mouser.com/ProductDetail/Panasonic/EEU-EB1J100S?qs=cEAFgkeRviBcbEMSGHCq5g%3D%3D

2.7

N channel 60V 600mA 700mW through hole transistor (ZVN4206ASTZ)

6

0.335

522-ZVN4206ASTZ

ZVN4206ASTZ

Diodes Incorporated

MOSFET N-Chnl 60V

https://www.mouser.be/ProductDetail/onsemi-Fairchild/2N7000BU?qs=k2x4EL1%2FKj6oeXMHAfSm5A%3D%3D

2.01

THD1512 11N (output 5V)

2

48.53

495-THD15-1211N

THD 15-1211N

TRACO Power

Isolated DC/DC Converters - Through Hole Product Type: DC/DC, Package Style: DIP-24, Output Power (W): 15, Input Voltage: 9-18 VDC, Output 1 (Vdc): 5.1, Output 2 (Vdc): N/A, Output 3 (Vdc): N/A

https://eu.mouser.com/ProductDetail/TRACO-Power/THD-15-1211N?qs=ckJk83FOD0X2IyoEoPcnmg%3D%3D

97.06

THD1512 22N (output 12V)

1

52

495-THD-15-1222N

THD 15-1222N

TRACO Power

Isolated DC/DC Converters - Through Hole Product Type: DC/DC, Package Style: DIP-24, Output Power (W): 15, Input Voltage: 9-18 VDC, Output 1 (Vdc): 12, Output 2 (Vdc): -12, Output 3 (Vdc): N/A

https://www.mouser.be/ProductDetail/TRACO-Power/THD-15-1222N?qs=ckJk83FOD0UVycxQxcHQFw%3D%3D

52

terminal block 12V

6

0.848

649-VI02215200J0G

VI0221520000G

Amphenol

Fixed Terminal Blocks TB RIS CLA 180 STACK

https://eu.mouser.com/ProductDetail/Amphenol-Anytek/VI0221520000G?qs=Mv7BduZupUi3lmtBYXCXvw%3D%3D

5.088

mikroe i2C isolator

1

16.74

932-MIKROE-1878

MIKROE-1878

Mikroe

Interface Development Tools I2C Isolator click

https://eu.mouser.com/ProductDetail/Mikroe/MIKROE-1878?qs=k5OWtXsTJao5L2rHk53Deg%3D%3D

16.74

mikroe shunt current sensor

1

24.18

932-MIKROE-4976

MIKROE-4976

Mikroe

Power Management IC Development Tools Current 7 Click

https://eu.mouser.com/ProductDetail/Mikroe/MIKROE-4976?qs=MyNHzdoqoQKaB6t4IH2nAQ%3D%3D

24.18

Serial eeprom 2kb DIP8/s

1

4.03

474-BOB-15439

BOB-15439

SparkFun Electronics

SparkFun Accessories Level Translator Breakout - PCA9306

https://eu.mouser.com/ProductDetail/SparkFun/BOB-15439?qs=P1JMDcb91o4XoNPr%252B0Xi4g%3D%3D

0

omhron G5LE relay

6

1.44

653-G5LE-1A4-DC5

G5LE-1A4-DC5

Omron

General Purpose Relays Power PCB Relay SPST-NO Sealed 5VDC

https://eu.mouser.com/ProductDetail/Omron-Electronics/G5LE-1A4-DC5?qs=pWf36BUtxBgFTk6ytLB7NQ%3D%3D

8.64

DIP for MCP23008 (18 pins)

2

1.33

575-1104731841001000

110-47-318-41-001000

Mill-Max

IC & Component Sockets STANDRD SOLDER TAIL DIP SOCKET

https://eu.mouser.com/ProductDetail/Mill-Max/110-47-318-41-001000?qs=5aG0NVq1C4xxoOYTdZ6dOw%3D%3D

2.66

DIP for OP27E (8 pins)

5

1.39

575-113308

110-13-308-41-001000

Mill-Max

IC & Component Sockets 8P GLD PIN GLD CONT

https://eu.mouser.com/ProductDetail/Mill-Max/110-13-308-41-001000?qs=WZeyYeqMOWeYjIS4tXLt7Q%3D%3D

6.95

DIP for DG411DJ (16 pins)

1

1.05

575-11044316

110-44-316-41-001000

Mill-Max

IC & Component Sockets 16P TIN PIN TIN CONT

https://eu.mouser.com/ProductDetail/Mill-Max/110-44-316-41-001000?qs=IGgAdOvCTsRH%252BXEWrwEHKg%3D%3D

1.05

header for raspberrypi

1

1.87

474-PRT-14017

PRT-14017

SparkFun Electronics

Raspberry Pi Accessories Raspberry Pi GPIO Tall Header - 2x20

https://eu.mouser.com/ProductDetail/SparkFun/PRT-14017?qs=a4BXICGgSn%2F%252BaML822b65A%3D%3D

1.87

IDC sockets (go on the ribon cable)

2

0.43

710-61200623021

61200623021

Wurth Elektronik

Headers & Wire Housings WR-BHD 2.54mm Female 6P Strt IDC Conn

https://eu.mouser.com/ProductDetail/Wurth-Elektronik/61200623021?qs=PhR8RmCirEabk1Ywkdxzfw%3D%3D

0.86

header socket 1 row 5 positions

2

1.97

571-5-534237-3

5-534237-3

TE Connectivity

Headers & Wire Housings REC 1X05P VRT T/H

https://eu.mouser.com/ProductDetail/TE-Connectivity/5-534237-3?qs=Eln3I3szM1klmLr%252BSZCsuQ%3D%3D

3.94

header socket 1 row 4 positions

3

1.46

571-5-534237-2

5-534237-2

TE Connectivity

Headers & Wire Housings REC 1X04P VRT T/H

https://eu.mouser.com/ProductDetail/TE-Connectivity/5-534237-2?qs=GYgf5PdsjzkI3hK2O1eiLQ%3D%3D

4.38

header socket 1 row 8 positions

4

1.74

571-5-535541-6

5-535541-6

TE Connectivity

Headers & Wire Housings REC 1X08P VRT T/H

https://eu.mouser.com/ProductDetail/TE-Connectivity/5-535541-6?qs=xDp7PGUNC%252BuqVwKJJvkWQw%3D%3D

6.96

header socket 1 row 10 positions

2

2.71

200-SSW11002GS

SSW-110-02-G-S

Samtec

Headers & Wire Housings Tiger Buy Socket Strip with PCB Tails, .100” Pitch

https://eu.mouser.com/ProductDetail/Samtec/SSW-110-02-G-S?qs=rU5fayqh%252BE0w1ORXZiBQpw%3D%3D

5.42

header socket 1 row 2 positions

1

1.02

200-SSW10202GS

SSW-102-02-G-S

Samtec

Headers & Wire Housings Tiger Buy Socket Strip with PCB Tails, .100” Pitch

https://eu.mouser.com/ProductDetail/Samtec/SSW-102-02-G-S?qs=rU5fayqh%252BE2ZEIMTlw%2FBLw%3D%3D

1.02

header pins 1 row 10 positions

1

1.24

571-1-826629-0

1-826629-0

TE Connectivity

Headers & Wire Housings 10P SINGLE ROW

https://eu.mouser.com/ProductDetail/TE-Connectivity/1-826629-0?qs=FazuUmncXom0aPLI6ZgGxg%3D%3D

1.24

IDC pins

3

1.32

571-1761681-1

1761681-1

TE Connectivity

Headers & Wire Housings IDC LOW PRO HDR 6P VERT HT BLACK

https://eu.mouser.com/ProductDetail/TE-Connectivity/1761681-1?qs=BqFpTYCQ3dLAeZ2wzdz7aw%3D%3D

3.96

PCB measurement board (pack of 3)

1

https://aisler.net/?lang=fr-FR

70

10k potentiometer

2

optional

0

R array sip9

1

optional

0

10k potentiometer bournds 3296W_vertical

1

optional

0

Raspberryp pi 4

1

63

https://www.kiwi-electronics.com/en/raspberry-pi-4-model-b-4gb-4268?src=raspberrypi

63

socket to cut for 3 THD

3

1.73

https://www.mouser.be/ProductDetail/Mill-Max/801-47-012-10-012000?qs=5aG0NVq1C4x40xNvDlnKzg%3D%3D

5.19

Interactive BOM list

Interactive BOM list

Before starting: how to soldering

How to Solder Electronic Components <https://www.sciencebuddies.org/science-fair-projects/references/how-to-solder>

Description

Soldering various RESISTOR on the measurement board PCB

1

 ../../../_images/110.jpg

Soldering thirteen 100 kOhm resistors

2

 ../../../_images/21.jpg

Soldering four 330 ohm resistors

3

 ../../../_images/33.jpg

Soldering four 4K7 ohm resistors

Soldering DIODE on the measurement board PCB

4

 ../../../_images/41.jpg

Soldering six diodes 1N4007

Soldering SCHOTTKY DIODE on the measurement board PCB

5

 ../../../_images/51.jpg

Soldering two Schottky diodes bat85 ou bat86

6

 ../../../_images/61.jpg

Soldering five DIP-8 sockets

7

 ../../../_images/71.jpg

Soldering two DIP-18 sockets

8

 ../../../_images/81.jpg

Soldering one DIP-16 sockets

9

 ../../../_images/91.jpg

Soldering twelve cut sockets for 3 THD

10

 ../../../_images/101.jpg

Soldering header socket 1 row 10 positions

11

 ../../../_images/111.jpg

Soldering two header sockets with 1 row and 8 positions

12

 ../../../_images/121.jpg

Soldering one header socket with 1 row and 2 positions, three header sockets with 1 row and 4 positions and two header sockets with 1 row and 5 positions. N.B. For the 2 positions header socket cut a header socket 4 or 5 positions.

Information about light-emitting diode

13

 ../../../_images/131.jpg

Installation of four light-emitting diodes

Information about MOSFET Metal Oxide Semiconductor Field Effect Transistor

14

 ../../../_images/141.jpg

Soldering six MOSFET ZVN4206 or ZVN4306

What is a CAPACITOR?

15

 ../../../_images/151.jpg

Soldering eleven 100 nF 50V tantalum capacitors

16

 ../../../_images/161.jpg

Soldering ten 1 µF 50V Electrolytic capacitors, pay attention to capacitor polarity

Warning

In this version, we used a shunt resistor of 2 ohms, which limits the current measurement to 48 mA. If the current is higher than this value, you just have to decrease the value of the shunt resistor. Don’t forget to change the shunt value in the config.py file (value associated to key ‘R_shunt’ in the OHMPI_CONFIG dict).

17

 ../../../_images/171.jpg

Soldering the 2 ohms shunt resistor

18

 ../../../_images/181.jpg

Soldering the two IDC 6 pins connectors. pay attention to the connectors orientation

19

 ../../../_images/191.jpg

Soldering six screw terminals for cable connection

20

 ../../../_images/20.jpg

Soldering six omron G5LE relays 5 VDC

21

 ../../../_images/211.jpg

Soldering the 2x20 header for connection with the raspberry GPIO

What is a Op-Amp?

In addition, the notch provides a way to visually identify the orientation of the package.

22

 ../../../_images/22.jpg

Place the three OP27 on their DIP-8 sockets the notch must face upwards

23

 ../../../_images/23.jpg

Place the REF03 reference voltage (2.5v) on its DIP-8 socket the notch must face the right side

What is an analogue switch?

24

 ../../../_images/24.jpg

Place the DG411 the notch must face the left side

25

 ../../../_images/25.jpg

Place the MCP23008 on its DIP-16 socket pay attention to the notches orientation

26

 ../../../_images/26.jpg

Place the Three THD, install the right reference at the right place according to the yellow boxes

27

 ../../../_images/27.jpg

Place the ADS1115 board on its female header 1x10 pins

28

 ../../../_images/28.jpg

Place the I2C isolator add-on board make sure you have right selection according to the red box

29

 ../../../_images/29.jpg

Place the two I2C level adjusters

30

 ../../../_images/30.jpg

Place the current click add-on board make sure you have right selections according to the red boxes