/diy/ - Do It Yourself

>>1942072
same anon after smoking a cig i forgot to put the n channel fet / pnp bjt on it to cut off bleed on the normally closed connection of the relay. for this circuit to work your relay must have both normally open and normally closed. every 3-5v relay i have seen has both.. this circuit is the opposite of the auto cut off battery charger . the diode is mandatory as it prevents a spike when cut off. the circle is a led idk falstad lists it as a circle

your resistor goes on the normally open connection and needs to be tuned to your circuit. you didnt post one so idk what it draws. this cannot be avoided as the battery has to power the coil . idk what relay you will use and i dont know what 18650 / cellphone battery you got. idk what your circuit will pull. but if its to low it cant make the relay connect