Recent content by almson

In case the neutral wire was wired up wrong. Duh. :-p Electrical codes don't always have overwhelming imperative behind them. But they increase safety slightly enough to be worth it. Plus, the electricians unions' get more work for themselves.

To elaborate, I'll quote wikipedia: So at very high frequencies, only a small part of a solid copper wire will be transmitting the electricity. The resistance goes up as most of the copper goes unused. However, the problem becomes one of geometry. If you give the wire enough surface area to...

I think I'm getting the picture. Photons interact with electrons the same way whether for radio waves or light waves, but a traditional antenna is not possible for light because the AC current would be ridiculously high frequency. So high that it just wouldn't be transmitted through copper wires...

This is actually a very interesting question. I know how PV cells work, in terms of quantum mechanics (photon hits electron, electron leaves orbit, etc.) I also know how antennas work, in terms of classical EM (changing magnetic field induces a potential). But... how do antennas work in terms of...

The voltages/fields/currents are canceled out. If you ignore resistance, pushing the first magnet into the set of coils while holding the second still (or just pretending the second magnet does not exist) will develop a current and a field. The coil's field will be opposite polarity to the...

It's possible to transmit electric power over large distances with just one wire. The Earth (ie, the planet Earth) is used as the current return path. But, there's some danger of electrocution for people nearby. So, we normally let the current return over a second copper wire (the neutral). But...

I think the replies missed some of the nuts and bolts. Computer chips have pins. If these pins are configured as outputs, they emit voltages (as inputs, they detect them). Usually, there are two possible voltages: 0V and 5V (or 3.3V or 1.8V, depending on the chip). The voltages can be used...

In my service the PCBs would also be batched into panels. In fact, that is the way everyone does things. I'm writing my own software to do it. Did you know that getting a computer to pack shapes optimally into a larger shape is one of those big, half-solved problems of computer science? The best...

It sounds like you're coming from the professional side of things, and cost may not be an issue for you. You don't mind spending $100 per board, correct? I suppose the target market would be the students and hobbyists, who are willing to sacrifice features for cost (and may make a lot of...

I have the idea of making a PCB quickturn website that both improves the ordering experience vs the competition, and hugely undercuts them by offering a simplified product. However, I want to gauge interest because the website would need a lot of orders to be profitable (about 10,000 per year)...

I am looking for something in the 15-50W range. Checking on mouser, the "switching power supplies" section is slim pickings, but "DC/DC converters" has a lot of things. In particular, a dozen can take 3-13.5V (the prefect range for my alternator) with some handling 100W. Unfortunately, almost...

Ahh, $500 for the BK Precision 8540 is too much. But a switching power supply is a really good idea. Let me look around for a good one, especially one that will put out something cool like the 19.5V that a Dell laptop takes. Btw, do you think there's any danger of feeding it too little...

Is there such a thing that can be bought? Are there schematics/BOMs to make one? Reason I ask is that I'm designing a human-power generator (think bicycle with an alternator) and I need a way to test it. What I'd like is a "watt sink" -- a device that draws a set amount of power, independent...