Power supply advice

audioguru said:

Oh? A 7808 lasts one million years. An LM317 lasts two million years. Does it matter?

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7808's aren't something you see very often?, but certainly 7805's, 7812's and 317's all die fairly regularly - they are pretty reliable, but poor enough for me to stock them for TV repairs!.

The LM317 does have better characteristics but it requires two external resistors while the LM78xx series don't. I don't know which is the most reliable though, my gut feeling would be the LM78xx series as there are less componants to fail.

I recommend that your first project is to build an LM317T based adjustable power supply. Use a wallwart for safety, but build everything past that yourself. There are plenty of schematics and plans available on the web.

A variable voltage supply will be very useful on down the road, and you will learn a lot by building one. It doesn't have to be fancy, just build it on perfboard and stick in in a cheap case of some kind. You will probably build a better one later on

"The Art of Electronics" is a great book, I have it, but a better book for beginners is "Getting Started in Electronics", by Forrest Mims

Good luck

- Rick

I've been pondering the need for a variable supply anyways for quite some time now, so I'll probably add that to my list of things-to-tinker-with.

Thanks for the book recommendation, I'll see if I can scrounge up a copy from the libraries around here.