Making Diodes Out of PNP Transistors!

(optional) Bic Whiteout Correction Fluid to mark reverse bias: Target

And, you're going to need your hands, too.

Now, let's start.

Now that you have your transistors, find the emitter. If you are using 2n2907a transistors, flip each transistor over, flat side facing down. In order from left to right the pins are collector, base, and emitter. If you are using another type of transistor and don't know which pins are which, you can search up, "*Insert Transistor Name Here* pinout."

Once you have found the emmiter of the transistor, just bend it back and forth until it breaks off. Next, bend the collecter leg forward, and then bend half of it down. Bend the base backward, and also bend half of it down. Repeat this with each transistor. Once you do that, each transistor should look like the image above. Next, get your Whiteout and draw a line on the side the base pin is pointing, to mark it's reverse bias.

Watch the video above for an explanation of how diodes work. If you cannot, let me explain what the video says. A quick note, though. The explanation uses electron flow, which is what really happens, where electrons flow from the negative terminal to the positive. This opposes conventional current, which was originally thought and is still commonly used for circuits.

Semiconductors like Silicon can become more conductive through a process called 'doping', in which some atoms in a semiconductor are replaced with an element with either fewer or more outer valence electrons. When you replace some atoms with elements that have fewer outer electrons than the semiconductor, there are not enough electrons for all the atoms to form bonds, leaving positively charged 'electron holes', which is called P-doping. When you replace the atoms with an element with more electrons, there will still be free electrons moving around that can easily be pushed by a voltage, called N-doping for Negative charge. when you put the P and N junctions together, the free electrons from the N-junction will be drawn to fill the 'holes' in the P-junction, creating a depletion zone. This is because now that there aren't any holes or free electrons, it will act like a semiconductor, lowering the initial voltage. If you were to connect a diode to a power supply in its reverse bias, the positive charges from the P-doped area are attracted to the negative terminal, as will the negative charge from the N region be attracted towards the positive terminal, widening the depletion zone, and resisting current flow. But when the diodes are used in forward bias, the negative charge from the N region is pushed to fill the holes in the P region, and then attracted to the positive end of the battery, creating a closed circuit.