A: Hey Woz - whatcha doin?

W: Oh hi Adabot - I was just adding some power protection to this circuit

A: Interesting - why does the circuit need to be protected?

W: Well a circuit needs to be protected for a couple of reasons.  One example is if I was to connect a battery to this incorrectly then electrical current might flow in the wrong direction and damage some of the components.

A: Oh - how do you make sure that doesn’t happen?

W: Well, we use a diode! 

W: By placing a diode at the circuit’s power input we ensure that current will only flow in one direction - the correct direction that we’ve designed the circuit to work with.

A: So - a diode is like a one way street for electrons?

W: Exactly - the electrons can only flow through the diode in one direction and they have a really hard time going back the other way.

W: The stripe indicates which end of the diode acts like a wall to block the electrons.

A: Diode!  Protector of circuits!

W: Yes, but diodes do more than just protect circuits, Adabot.

A: Oh?  What else do they do?

W: Some diodes emit light when we pass current through them.  We like to call these “light emitting diodes” or L-E-Ds for short.  Maybe you’ve heard of them?

A: LEDs? I love LEDs!!

W: I thought so!

A: So that’s what “D” stands for in LED.  D is for - Diode!

W: That’s right.

W: Well, looks like this circuit’s all done - how about we go test it out?

W: Adabot - are you coming?

A: Sorry Woz - I’m an electron in a diode - I only go in one direction!

A:  Ow … Ow …

W: Oh Adabot, let’s go.

This guide was first published on Dec 19, 2014. It was last updated on Dec 19, 2014.
This page (Transcript) was last updated on May 10, 2020.