Ok thanks. PC1 should be accessible enough to solder.
And I guess Rodeastat would indeed be much more interesting for my application. But I've these couple Cheapstats already so I'll try to make them work before moving to the next generation.
Ok, I realised this morning that I need both the flash and EEPROM files loaded on the apparatus. Yep, I'm a beginner in AVR
Also, I found that the initialisation of the different profiles on the EEPROM are in comment in the source file CheapStat_v2.c (from line 260). That's why no profiles appear in the main menu. So if you want to rebuild a flash and eeprom file, you need to remove the comments from this section.
When I'll finally understand all of this, I'll post my code. I'm trying to implement ASV.
Hi...i am a new user here. As per my knowledge potentiostats are the foundation of modern electrochemical research, they have seen relatively little application in resource poor settings, such as undergraduate laboratory courses and the developing world. One reason for the low penetration of potentiostats is their cost, as even the least expensive commercially available laboratory potentiostats sell for more than one thousand dollars.
At this concentrations, it should not be too much of a problem to measure Pb, even though GC electrodes are not very sensitive. Is -400mV a low enough potential to accumulate Pb onto the electrode ? Have you tried at -0.8V?
Also, I don't know if there is Cu in your solution but I remember having some disappearance of the Pb signal with addition of Cu.
If it doesn't work, maybe try a gold electrode which is a bit more sensitive to Pb. Or maybe modify your GC electrode by depositing some bismuth on the surface.
Unfortunately, I don't know of any easy way to do this. There is a little flash chip (IC4) which is there to provide external memory which isn't actually used at all. It uses an SPI interface - like and SD card. If you don't include this chip you might be able to hack in and SD card in its place. Connecting wires to the pads maybe - it would be a bit dicey though. You would also have to modify the firmware to read/write to the SD card.
@Will-Dickson Thank you so much for the suggestions. I could make it work with the AVRISPMKII programmer. Also, your modified firmware, especially the makefile was very helpful and made my work absolutely easy. Thank you once again.
We are currently out of Cheapstat stock and at this time we don't have plans to restock in the forseeable future. However, if you want to make one yourself, we do still have the bare Cheapstat PCB for sale here. We have also just updated the Cheapstat documentation to include the bill of materials for this board. Let me know if you have any questions about this.
Going forward we will be focusing most of our efforts on the Rodeostat open source potentiostat. If you are interested in using the Rodeostat or have any questions, please let us know and we will be happy to help.
You could use the linear sweep voltammetry (LSV) test in the cheapstat firmware to do anodic stripping voltammetry. The settling time parameter can be used to set the time for your preconcentration step.
There is also a squarewave voltammetry (SWV) test in the firmware. This would almost do what you want for squarewave anodic stripping voltammetry. Unfortunately there doesn't seem to any period at the beginning of the trial which could be used for your preconcentration step. However, I think it would be pretty easy to modify the firmware to add this. The SWV test in implemented in the SWV_test function in cheapstat.c. For an example of how this delay at the start of the trial could be implemented you could look at the LSV_test function which implements the linear sweep voltammetry.
Corrosion monitoring and analysis usually takes a large dynamic range (eg polarization curves etc.) or requires measurements with respect to open circuit (LPR, EIS , OCP-monitoring). These are not well-suited to the current version of cheapstat.
By default the new potentiostat has +/- 1, 10, 100, 1000 uA current ranges (16-bit ADC) and +/- 1, 2, 5, 10 V output ranges (12-bit DAC). Other ranges are possible by changing a resistor (and possibly capacitor) on the PCB - up to a max of around 20mA.
We are currently developing a programming library and reference firmware for the new Potentiostat. These will be available when we first launch the device. Currently implemented tests include: cyclic voltammetry, sinusoidal voltammetry, constant voltage, linear sweep, and chronoamperometry.
The new potentiostat is controlled over USB. So all test parameters are set/retrieved and all tests initiated/stopped over USB. Also, data is streamed to the host PC, as it is acquired, over USB during tests. Because of this test duration is not limited by the MCU memory.
We should have the firmware ready fairly shortly. While I can't put an exact date on this I'm hoping we will have it ready by early March. Once the firmware is ready we will add the new potentiostat as a product on our website.
At launch we won't have software for the host PC with a Graphical User Interface (GUI) etc. This is definitely something we are actively developing, but it won't be ready right away. We will have a serial library (Python/pySerial) for controlling the device along with example programs demonstrating how to set/get parameters, start trials, receive data, etc.
Also, all hardware designs, firmware, and software will be open source. I will be making these available soon.
I haven't modified the cheapstat to have a +/- 1uA range - however I'm pretty sure this should be doable.
Also, we have a new potentiostat design coming out soon which is basically a shield for the teensy 3.2 development boards (https://www.pjrc.com/teensy/teensy31.html). It has current ranges of +/- 1, 10, 100, 1000 uA and output voltage ranges of +/- 1, 2, 5, and 10V. We just got a batch of the new of the PCBs in - I've attached an image below. We should have them up on our website within the next 2-3 weeks.