After a discussion about the total current draw of the fans being 80mA as opposed to the originally thought 180mA as purported on the seller website, an alternative to the power hungry relays were sought. Doing a brief amount of research, a set of 2N3904 NPN transistors was decided upon. Each transistor has the capability to allow up to 200mA of current through with a minimal voltage drop as noted in the manufacturer datasheet and as tested in Multi-Sim seen below.
It should be noted that a slight increase to the input voltage, which will be coming from our adjustable regulator, is required due to a slight voltage drop across the transistors. Once simulated in Multi-Sim, this setup was tested on the bench which confirmed it's functionality.
Tested input of 14.6V into the regulator with a 12.3V to 12.4V output that is wired to the collector of each Transistor. 1kOhm resistors were wired into the input of the base with a 3.3V signal (emulating the pico GPIO signal) to confirm functionality of the transistor and their capability to activate a fan array.
Comments