Ive got an off-brand 5V 1000mA iPhone charger cube that I have cut apart to use in a small project box. I want to use the usb port to charge the phone and also power the circuit. The circuit is an ATtiny85 running a modified capacitive touch sketch that switches the state of a relay. I've tried soldering onto some spots on the charger which worked, but when the phone is plugged in, the voltage fluctuations changed up values in the sketch so much that I'm not seeing desired results. Any help on what to do?
You are running the relay off this power, and the arduino? Anything else? how about what the relay is controlling?
If that is the only two things, and it is a 1000Ma supply, I would think it would provide enough power.
How about when the phone has been plugged in for a while (hour), is it still acting badly? Maybe the phone is drawing it down?
and it is a 1000Ma supply,
I think it is more likely to be a 1000 mA supply. Unless it is a small thermonuclear device.
but when the phone is plugged in, the voltage fluctuations changed up values in the sketch
Have you measured the voltage coming out of this supply. How does it change?
Be careful with those knock offs. There have been recent cases of electrocution due to shoddy internals including inferior insulation of inductors:
Apple actually started an exchange program in hopes of getting them (some, anyway) out of circulation.
@Grumpy, What's the difference in 1000Ma and 1000mA? What URL defines these? Just curious.
jackwp:
@Grumpy, What's the difference in 1000Ma and 1000mA? What URL defines these? Just curious.
Ma stands for Mega Amps, that is to the power of six. So 1000 Ma is ten to the power nine amps about the power of a power station. The lower case m stands for milli that is ten to the power minus three.
@grumpy.
I find that MA means mega amp, not Ma, want to be really technical.
Well for amps it should be an upper case A not a lower case one, but I was cutting you some slack on that.
Be careful with software as well. Orcad PSpice will interpret both m and M as milli, and only a MEG as Mega. I don't know how many times this has gotten me.