How a semi-conductor diode works

This is a good video because it is short and to the point. It also explains a little bit about how they "dope" a diode.

Here are two other videos by the same professors I thought were good as well:

Hydraulics

Specific heat

Relays

What I've so far with relays is the first thing you ask yourself is "does the relay click"? If the relay doesn't work then you troubleshoot that part of the circuit and find out why. Relays have a solenoid and it's also a load itself. It should act like any other load and have approx 12 volts before the relay and close to zero after it. If you have less than 12 volts before the relay then you troubleshoot the power side of that part of the circuit. If you have more than zero after the solenoid than you troubleshoot the ground side after the relay. The main thing I took away from this was for step one ask myself "Does the relay work"?

Secondly I learned to tell the difference between HRVD's and opens. If it's measurable then it's an HRVD and if it's not then it's an open.

Electrical week 2

There are a few things I've taken away from electrical so far. There are high resistance voltage drops, opens, and shorts. One of the things that I'm still figuring out is determining whether it's a short to power or a short to ground. It seems that when a short bypasses a switch it is a short to power. If it blows a fuse then it is a short to ground. Another interesting scenario is if there is a HRVD that drops so close to zero it almost looks like an open.

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Electrial 101

So far what I've learned in electrical is that most of what we'll be dealing with is HRVDs. The first thing we're supposed to do is connect our negative lead to the battery post itself. Then we go to the load and start from there. If it's on the power side we'll see a HRVD before the load. If it's on the negative side we'll see voltage after the load that doesn't look like zero. If we have an "open" then there's no current flowing. If we have a short then we'll be looking at best case scenario a blown fuse and worst case is burnt wires. Also the main idea Jeff pounded into my head is "No current flow, No voltage drop".


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