Electronics - Diodes

Diodes are less interesting than you might think.

But they are actually very useful.

Diodes are the things you would sick in an electronics circuit if you wanted power to only flow in one direction.

They act like a valve.

They tend to look like this.

If you have something like a wind powered generator, it would act as a motor if you connected it to a battery.

If you want to make power rather than use power, you need to stick a diode between your windmill and your battery so that power can only flow one way.

If you didn't have diode, the windmill would charge the battery if it was spinning fast enough, but then if the wind died down, the battery would power the windmill. Not such a bad thing for a novelty windmill sitting proudly in your front yard next your flamingos, but not so desirable if you happen to be a power company.

Perhaps even embarrassing if you happen to be a power company.

Sometimes they look like this and are called LED's or Light Emitting Diodes.

You would have seen them before in just about everything electronic. They are absurdly reliable little things, and put out lots of light without all the heat that normally comes with bright things. As a result they are very thrifty with their power use, so perfect for an indicator light or low energy keyring torch.

Any light that also puts out heat is a bit of a waste of energy if you don't also want the heat.

There are a couple of other diodes that I've heard of.

One is a Schottky diode, All diodes create a bit of a drop in voltage. I'l not sure how, probably they waste it as heat, but the Schottky diode is a bit special because it has less of a voltage drop. It costs a bit more, but is useful in things that are solar powered or need batteries to last a long time. Anywhere saving every bit of power counts.

Another special diode is a Zenner diode. As far as I can tell, the cool thing about this device, is that whilst it allows current to flow in only one direction, it breaks down, and allows current to flow backwards at a certain pre-designed voltage. This might allow you to put a T-junction into your circuit in such a way as to normally stop current flowing down the T, unless the current gets too high. If the current is too high at any point, the Zenner breaks down, and allows flow. If you were trying to charge a small rechargeable battery with a little windmill, you could use one as a charge regulator by sending some of the current to say a light bulb to be wasted, if the voltage got too high (too much wind speed), of if the battery was fully charged.

I think.

Do doubt there is a lot more to diodes than I know, and there's at least some chance this is all wrong.

If you are planning a Mars mission or anything important, I'd do a little more research, and not rely solely on this information.

And good luck with that Mars mission.

Not just Electronics - Diodes. 120 Things in 20 years

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