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Home Brew Forums > Home Brewing Beer > Electric Brewing > Actuating valves using rotary switch + diodes?
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Old 05-13-2012, 01:11 AM   #11
passedpawn
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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.
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Old 05-13-2012, 01:51 AM   #12
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Quote:
Originally Posted by passedpawn

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.
Yeah I know LEDs are diodes, hence my idea. But my valves supposedly draw 45-100mA, and it will only be a single valve to each diode, so I wonder if any LEDs that can handle that.

So given the current, and that it'll be 12 volts, you think that the 1N4001 will suffice? If so, my only concern is that the voltage drop isn't too high for the valves to function properly.
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Old 05-13-2012, 03:16 PM   #13
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The forward voltage drop for the 1N4001 is 1.1V so your valves would get 10.9V. This should work but you need to check the datasheet for your valves for the minimum voltage to turn them on.
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