Determining voltage supplied to CheapStat in CV
-
I'm trying to get the voltage waveform being applied to the CheapStat in cyclic voltammetry using an NI USB 6009 Data Aquisition Card. The graphs obtained are irregular and have the following issues -
1.The magnitude is constant from -1.5V to 1.5V irrespective of the voltage range I set.
2. Even if number of scans is set to 1, the number of cycles are more than one and vary with the value of slope (number of cycles decrease if I increase the slope)
I checked the voltage between working and counter electrodes. If I check it between any other pair only noise is obtained.
How do I check the actual waveform and which electrode pair should I use for it? -
The Cheapstat is a feedback device - running a control loop - so it won't really work correctly without something connected to it. In general it is trying to control the voltage between the working and reference electrodes via the counter electrode.
You might start by using a simple dummy cell consisting of a single resistor. Connect both the reference and counter electrodes to one end of the resistor and working electrode to the other end of the resistor. Then maybe try a simple test such as a linear sweep or cyclic voltammetry. Select the resistor so that the currents are with the measurement range e.g. 50K might be a good choice for the +/- 50uA range. Measure the voltage across the resistor. If you are using a single ended input on the DAQ card (or oscilloscope) make sure to connect the ground to the working electrode and the probe to the counter/reference electrode.
In general the Cheapstat is not capable of a full -1.5V to 1.5V swing. The actual range is more like -0.8 Vto 1.6V. Below -0.8V the output is nonlinear.
-
Thank you. It worked well with 10k resistor for 50 microamperes current range for voltage applied from -700mV to 700mV.
-
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.