I'm pretty new to 'breadboard-ing' and I'm beginning to work with and need help understanding some basic concepts that I can't grasp.
Basically I've made a basic circuit with a push button for an LED light. There circuit is a basic circuit, powered by two double A batteries and there is a 220\$\Omega\$ resistor on the cathode side of the LED (from what I understand it doesn't matter which side it's on but that's the way I have it set):
The LED lights up when I press the push button. Victory.
The next set up is with a 3VDC Motor (350mA) and when I plug that into the batteries directly it spins. When I plug it into the circuit where the LED is (with the resistor) and press the push button, it doesn't spin:
BUT, when I remove the resistor and put a straight wire into the circuit it works great when I press the push button:
So obviously the resistor causes enough resistance to not spin the motor in the circuit BUT 220\$\Omega\$ seems like a very small resistor and would seem as though that should resist the circuit so much that the motor doesn't work at all.
I don't have a resistor smaller than 220\$\Omega\$ to try out but obviously anything more than that won't work if this doesn't work. I'm just trying to understand the concept of why this wouldn't work because I'm trying to chain some LEDs and motors together and the resistance obviously causes an issue.
I tried a capacitor after the resistor too but that didn't work (but maybe my concept is off so far; as I said I'm pretty new to this and am having trouble even knowing what to search for to get answers).
Thanks for your help!
Best Answer
You say that the motor draws 350 mA. If you pass 350 mA through your 220 ohm resistor, Ohm's Law says there will be a 77 volt drop across the resistor - since you only have a 3 volt battery, this obviously won't work!
Ohm's Law indicates that 3 volts across 220 ohms will only result in a current of 13.6 mA.
Common LEDs typically have a maximum current of 20 - 30 mA, so they cannot be connected in series with your 350 mA motor - the LED would vanish in a puff of smoke!
If the motor is designed to operate on 3 volts, it should be connected directly to the 3 volt battery, with no series resistor.