I'm trying to understand the circuit in this PCB taken from a cordless hot glue gun. Battery voltage is 18-19v. I've been able to identify most of the components but not all. And most importantly I would like to understand what the circuit is doing.
What I Think I Know about the Circuit
- Q1 Fairchild 4486 TrenchMosfet
- Pin 1 is Gate (top left)
- Pin 2,3,4, are Source
- Pin 5,6,7,8 are Drain (entire right side)
- R1 31 Ohm
- R2, R3, R4 1 Ohm
- R5 20 Mega Ohm
This circuit sits between the battery and heating element. I think it just makes sure the drain on the battery isn't too fast and that it isn't shorted. Please correct me or confirm my theory.
I'd like help to identify the unknown components then understand what the circuit is doing. My ultimate goal, if possible, is to control the heating element on/off with an Arduino or similar control circuit to maintain a specific temperature via a thermister added near the heating element.