Wondering how to get inexpensive 10 mA power supplies for electrochemistry
The cheapest way is to buy some LM317 voltage regulators, and some 124 ohm resistors. The data sheet for the LM317 will show you how to connect them, and parts cost will be about 50 cents per channel. Plus, of course, a DC power supply of at least 3 volts greater than the electrochem potential, and at least 200 mA for 20 channels.