As part of a school physics project my group was given 2 TEC1-12706 and was told to find some way to generate electricity via Seeback effect and recycled materials. Due to low efficiency of the TEGs, we are only able to generate around 1.5~1.1V when connecting both TEGs in series during testing. Our idea is to connect the TEG to a pot and use it as an egg timer. Our circuit is as shown:
At time = 0, the TEG will charge the capacitor.
Few seconds later, due to drop in temperature of hot water, Vse < Vcap, stopping charging of capacitor.
Few minutes later, the Vse < Vnon-inverting input (adjusted using the variable resistor), and op-amp's output will turn on, allowing the capacitor to turn on an LED, or some other device to indicate that the egg is cooked.
However, I am facing an issue with my circuit. Often, when the TEG voltage drops below the capacitor voltage, the capacitor begins to discharge quickly. This happens even if no output is connected to the op-amp. I suspect this is due to the supply voltage of the op-amp being less than stated in the datasheet (Vs = 2-36V). Is this indeed the case or have I made another design error in my circuit?