Arduino-based Potentiostat

Hello,

I am trying to replicate this paper by building an arduino-based potentiostat to conduct some electrochemical tests for my research. I bought all the parts listed in the paper but I’m feeling a bit lost about whether I can use a solderless breadboard for this. If so, how should I make the connections? Any tips on how to build this circuit will be extremely useful.

Thank you

Yes, you can use a breadboard.
There are pictures that show how the connections of a breadboard are. Usually horizontal lines with power and vertical lines of 4 holes.

Do you use a LM324 ? It has four OpAmps, so you need two LM324.
The PDF file shows the schematic and the Arduino sketch.

What is the problem ? Understanding the schematic ? Knowing which pin is what ?

Potentiostat: https://en.wikipedia.org/wiki/Potentiostat

I am using 85AP8PM OP07CP and I have seven of them. I don’t have a great background in electrical engineering so I’m having a hard time understanding how the wires connect on the breadboard.
If you can help me with that, it’ be really helpful

You have to tell what you don’t understand. I can not see from here which breadboard you have and which package of the OpAmp (I hope the PDIP package). Have you seen the datasheet of the OpAmp ?
Is there someone at your place who can help ?

I have all these details in an excel file here. Is it okay if I message you with that?

I don’t know what is in that file :confused:
Please try to explain what you don’t understand.

You should have a OpAmp, a breadboard and jumper wires. Put the OpAmp over the empty middle row, assign +V and -V and GND to horizontal power lines and use wires to power the OpAmp. Can you do that ?

OK,

1st we have to know if all your parts have leads that can “plug” into the wireless breadboard (WB).

If you are not sure, post the EXACT part number of what you purchased. The last few digits/letters are most important for us to know the physical part you have.

Next
You link to some amazon WB (remember wireless breadboard). Are these the exact parts you have or similar to what you have? We need this to show you how the WBs are connected internally.

Would best if you could post you exact parts list.

Don’t let all this overwhelm you, it is not as difficult as it seems. With a few bits of information you will be able to see how it all goes together. Now if you had to design it yourself, that would be a different story.

One thing to remember, there are a number of connections, if you miss one the circuit will not work so attention to detail and patience is needed here.

You could print the schematic.
This schematic (use the PDF file to print the schematic, this image is made smaller):
afbeelding
The bold arrows pointing downward are connected to GND.
The OpAmps need a positive and negative voltage to power them.
Then you need this, you can print that out as well:
afbeelding
Put them on the breadboard:
afbeelding

There are two horizontal strips at the top and the bottom.
Suppose that you use 6.5V, as in the schematic. Then assign one to +6.5V, one to -6.5V and one to GND.
Use jumper wires to give each OpAmp 6.5V to the VCC- pin and -6.5V to the VCC+ pin.
As you can see, the GND is connected to the IN+ of two OpAmps, you can make those connections as well.

Can you make a photo of what you have so far ?

I am so sorry I shared the wrong paper. Here the right one.

Here’s a list of parts I purchased based on the circuit diagram in the paper-

  1. Arduino Mega R3 - https://store.arduino.cc/usa/mega-2560-r3

  2. Op-Amps(OP07CP) - OP07CP | Buy TI parts | TI.com (datasheet is on this website)

  3. 100k Potentiometers- https://www.amazon.com/Uxcell-a12022200ux0324-Linear-Rotary-Potentiometers/dp/B0169OP0XW/ref=sr_1_9?dchild=1&keywords=100k+potentiometer&qid=1616699019&sr=8-9

  4. 1k Resistors- https://www.amazon.com/EDGELEC-Resistor-Tolerance-Multiple-Resistance/dp/B07QG1V4YL/ref=sr_1_1_sspa?dchild=1&keywords=1k+resistor&qid=1616696455&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzT0JaQUFDWk1JTlY1JmVuY3J5cHRlZElkPUEwNDA4OTg4MlZMVFJPQTNQOU9VMCZlbmNyeXB0ZWRBZElkPUEwNTQyMTU4MUJKMk1OMUhVR1o3MyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

  5. 10k Resistors- https://www.amazon.com/EDGELEC-Resistor-Tolerance-Multiple-Resistance/dp/B07QJB31M7/ref=sr_1_1_sspa?crid=LZYFNUHLFSUH&dchild=1&keywords=10k%2Bresistor&qid=1616696331&sprefix=10k%2Bres%2Caps%2C215&sr=8-1-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyT0xRRjNRUkI1OVBUJmVuY3J5cHRlZElkPUEwNzYzNzcxM1E0R0QzUElGR0NVOSZlbmNyeXB0ZWRBZElkPUEwODA3NzIxMkFNVEJWRVdPMUFHTCZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=14.99

  6. 100k Resistors- https://www.amazon.com/EDGELEC-Resistor-Tolerance-Resistance-Optional/dp/B07HDG9K8P/ref=sr_1_3?dchild=1&keywords=100k+resistors&qid=1616696000&sr=8-3

  7. Male Header Pins- https://www.amazon.com/MCIGICM-Header-2-45mm-Arduino-Connector/dp/B07PKKY8BX/ref=asc_df_B07PKKY8BX/?tag=hyprod-20&linkCode=df0&hvadid=385179140364&hvpos=&hvnetw=g&hvrand=18149627941423696336&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011796&hvtargid=pla-823709055595&psc=1&tag=&ref=&adgrpid=82240853201&hvpone=&hvptwo=&hvadid=385179140364&hvpos=&hvnetw=g&hvrand=18149627941423696336&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011796&hvtargid=pla-823709055595

  8. Solderless Breadboard- https://www.amazon.com/Breadboards-Solderless-Breadboard-Distribution-Connecting/dp/B07DL13RZH/ref=sr_1_6?dchild=1&keywords=Breadboard+Arduino&qid=1616708925&sr=8-6

  9. 33uF Capacitor- https://www.amazon.com/6-3X11-105°C-Aluminum-Electrolytic-Capacitors/dp/B076H5M74K/ref=sr_1_1_sspa?dchild=1&keywords=33uf+capacitor&qid=1616697478&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzVjU2S0wyMzk4UkpEJmVuY3J5cHRlZElkPUEwMDc5ODAzMU9YTTZQNExENk9JOCZlbmNyeXB0ZWRBZElkPUEwMzk1NTgzMzg0UlIxTk9aS0dCMyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

  10. 9V battery- https://www.amazon.com/Rayovac-Batteries-Premium-Alkaline-Battery/dp/B00V4KW1GG/ref=sr_1_4?dchild=1&keywords=rayovac+9v&qid=1616709222&sr=8-4

  11. Gator Clips- https://www.amazon.com/WGGE-WG-026-Pieces-Colors-Alligator/dp/B06XX25HFX/ref=sr_1_6?dchild=1&keywords=gator+clips&qid=1617629136&sr=8-6

  12. Jumper wires - https://www.amazon.com/Elegoo-EL-CP-004-Multicolored-Breadboard-arduino/dp/B01EV70C78/ref=sr_1_1_sspa?crid=3F72WAFBM1D2B&dchild=1&keywords=wires+for+arduino&qid=1617629221&sprefix=wires+for+ardu%2Caps%2C173&sr=8-1-spons&psc=1

  13. Battery clip connector - https://www.amazon.com/Battery-Connector-I-Type-Plastic-Housing/dp/B07TRKYZCH/ref=sr_1_15?dchild=1&keywords=battery+clips&qid=1617631006&sr=8-15

  14. 14 Gauge Solid Wire- from Home depot.

These are the exact parts I have. I am also figuring out the code from the paper I linked earlier. Can you tell me how to integrate these parts on a breadboard based on the circuit design? I have to disclose that this is my first time working with electronic circuits.

Here’s what I have so far-

This is my arudino board-

Thank you for all the help! I really appreciate it. :smiley:

Just read the datasheet for the op amp to get the pinout and connect the wires
as shown in the schematic. There’s really nothing else to know.

Don’t bend the pins open. Bend them a little together. To bend the pins together, I put them down on a table, so I don’t need plyers. You have put the pins one row too far in the breadboard.
Then start with powering the OpAmps with the jumper wires.
The new circuit has seven OpAmps ? Then you probably need both breadboards.

I know it likely tough to get suggestions from every side but…

I think you have too much unused space between your parts.
I would try to keep the physical parts laid out similar to the schematic. Also know you can put resistors in standing up, they don’t all have to be laying down.

image

I would start with U1 and its associated components then move through the circuit. You really would like to get it all on one board. Both for noise rejection and durability while testing.

You should purchase 20 ceramic capacitors. 0.01µF 15Volts or more.
They should not be expensive. They are needed because each opamp must have a capacitor from +Vcc to ground and -Vcc to ground. This is standard design. Probably not shown on the schematic for simplicity.

Do you have a multimeter? One would be really helpful when troubleshooting the circuit. For initial testing you should test each amplifier function by itself, either as you build or after you are complete.
This might not be intuitive but simply getting the function you want is not adequate. There could be several mistakes that would make the output seem to work but might be limited in range or other negative effects.

Thank you John. Would you be able to make a rough sketch of how the breadboard connections go?
I’m really having a hard time translating the schematic into a breadboard circuit.

I have a multimeter and I will get the capacitors today. It’s just that the paper includes pictures of the author’s breadboard circuit and it doesn’t seem to have any capacitors.

I suggest to start with a simple circuit 1 op amp with battery + -, and ground.
R0e64aafa80dfb408285b70165519fa2a

use 9V batteries instead of 15V

1 Like

Here is a start, I’ve laid out the first opamp.

Regarding the capacitors, notice none of the authors is associated with the electrical engineering department. On anything electrical, especially with large value resistors, noise will be picked up on the wire and component leads. A capacitor from the power to ground will help alleviate the noise and you circuit will perform better and with less “bouncing around”.

Hey John! I’ve made the connections for the first opamp as you suggested. I’m not too sure if I connected the right resistors, do you mind color coding the 1k,10k,100k resistors and the 0.01uF ,33uF capacitors? Also, what is that big circle and the ‘to pot’ connection? I also see a resistor outside the breadboard which I don’t understand.

This is the potentiometer I have which looks a bit different compared to what I saw on youtube videos.

Thank you so much for taking your time to help me with this!

Stereo potentiometer contains two actual potentiometers, ganged together.

Pot:

In addition, if its an audio the resistance will not change linearly with rotation. It will have a log function.
I’m not familiar with the operation of a potentiostat. Will the pot be used a lot?

Layout.
I think it is best if you trace the components. You will need this ability to finish. But you will need one additional bit of information:

image

So you use the attached diagram to id the pins from the schematic.

For example Amplifier Pin 6 and Amplifier 2 have a 100K connected between them. Look a the diagram and see what resistor is connected to those two pins and it will be a 100K.

It is easier than you think. I realize your are in uncharted waters and it would help if someone was looking over your shoulder. However I am confident anyone who would be working with such a cell has the where with all to grasp the schematic → Pin # → pin location → physical layout.

Hi,
What does the dual potentiometer have written on it?

Thanks… Tom… :grinning: :+1: :coffee: :australia:

The 1st potentiometer is used to control the input voltage. The second one is used to read currents in the uA to mA range. The potentiometer has ‘B100K’ written on it.
I also have a polarized 33uF capacitor and I’m not sure if I can use it here.


These are some of the connections I’ve been having trouble figuring out.

Thank you!