Electronics - Transistors

Transistors have to be one of the all time great inventions. Right up there with the sharpened stick, fire, deodorant on public transport, and the wheel.

Transistors are in just about everything electronic. They are what makes all that cool stuff like your computer work. They do it all day long, and there are sqillions of them.

That's pretty much all you need to know about them, but I'm going to tell you more anyway. Which is a little surprising because I don't really know a lot about them yet, but what I do know has opened some doors to a slightly better understanding of what's possible with this electronics stuff.

I made a program in my little chip that controls the speed of a little motor. The motor, and the chip were both powered by the chips power supply, but the chip cant control the motor directly. If you plugged the motor directly onto the chips pin, it would suck too much power though the chip and burn it out.

I actually did that, but oddly it was while I was trying to do the very thing that avoids putting all that power through the chip.

What I was doing was using a transistor.

This is the device here. The chip is on the board with all the short white wires on it. That plugs into the breadboard (white thing with holes for wires)

A transistor comes in various guises. The one I'm playing with is a small electronic component with three legs.

That small black thing on the right of the bread board is the transistor.


The other things in that picture of note are the motor on the left, and the two battery packs. One under the breadboard powering the chip, and the other at the bottom of the picture with two visible batteries. There should be four batteries in that pack, but I needed two of them to run my camera.

Doing 120 things in 20 years is teaching me new things all the time. Today I learnt that it's very difficult to take a photo of your camera's batteries.

The reason there are two battery packs, is because I'm powering my control circuit (the bit with the chip in it) with one of them, and I'm pretending the other is a 12 volt car battery. It isn't, but I have a good imagination.

The reason I'm pretending is because I want to learn how to power my motor from the battery (12 volt 200 amp hour deep cycle (great big (like a car battery but bigger))) I use in my aquaponics system as a back up power supply to keep the pumps working in case of a power outage.

I turns out if you apply a small voltage to a transistor's centre pin, and then pass a large voltage through the other two pins, you can use a transistor as a switch. Not so surprising really because that's what a transistor is. The small voltage to the centre pin allows a large voltage through the other pins.

Stop the small voltage and you stop the large voltage. Start the small voltage, and you start the large voltage.

Very clever, and very, very useful.

It's an amplifier.

It's also a digital switch.

I'm guessing it's some other stuff as well.

So far, transistors are my favourite component, except perhaps for chips. But I think chips are full of transistors, so they don't really count. In fact I think they're full of all kinds of stuff. Their real name is "Integrated circuits" or "IC's". I'm guessing there's a stack of stuff integrated into them.