Probably a simple question, but figure I should ask. I have a circuit that is running off 12v. The plan is to run it off a car battery. My question is this, the circuit is 12v, pulling roughly 120mA, whats the risk of frying the circuit? And, should I put a fuse inline?
A 1/4 amp inline fuse wouldn't hurt, just to be safe. If you are using the battery that is not installed in a vehicle, the voltage may be higher than 12v when fully charged.
Ok, I will add the fuse. Seemed to be a good idea. Not to worried if the voltage goes a bit over 12v, the parts I chose are rated for it...main reason I chose them. Was more worried about the amps behind the battery, but I think I understand that a circuit will only pull what it needs, and wont get "pushed" by them. Is that correct...not sure how to say it but I know what I mean.
Ok, I will add the fuse. Seemed to be a good idea. Not to worried if the voltage goes a bit over 12v, the parts I chose are rated for it...main reason I chose them. Was more worried about the amps behind the battery, but I think I understand that a circuit will only pull what it needs, and wont get "pushed" by them. Is that correct...not sure how to say it but I know what I mean.
Yes, the latter is correct. At the given voltage(s) the load was designed for it will only draw its rated current regardless of what the power source is capable of.