Originally Posted by emjay
Thank you. Now I just need to figure out what type of diode is most appropriate, and whatever the particular specs I need.
Does running current backwards across an LED ruin it? I may just use LEDs if I can maintain enough voltage to the valves, and give myself a nice little indicator diagram.
An LED is a diode and will only conduct in one direction. They can withstand a reverse voltage (i.e., cathode is higher than the anode) up to a certain point, at which they will break down and become a short circuit (or open circuit).
Most LEDs are rated for under 50mA continuous current. Over that, they burn. I'm sure your application requires more than that amount of current, so that won't work for you.
Probably the most common diode is the 1N4001. It will run you 8 cents, you can probably get them at rat shack. It's a 1A diode.