T&L Publications

You might want to look at one of the better stepper motor tutorials available on the web...<p>http://www.cs.uiowa.edu/~jones/step/<p>This will answer most of your questions.

If you're a "newbie", and want a "KISS" circuit to optoisolate logic 1s and 0s, try the H11L1. It has everything built in except the current-limiting resistors for the LED at the input and the pullup for the open collector logic gate at the output. Also, it's made with hysteresis...

Check your assumption that it's a ground loop by unplugging the CD and shorting the input. If you've still got buzz, you might have a problem in the tube preamp/amp. Check the caps first -- if it works otherwise, hum on well-designed tube amps can be a result of dried out/hi-Z electrolytics.

P = V * I 3.9W = 12V * Fan Current Fan Current = .325A Your fan requires 325mA current.<p>8Ah = .325A * h hours of fan operation h = 24.6, meaning a fully charged battery will power your fan for 24 hours.<p>8Ah = .12A * h charging hours 66.6 charging hours to acieve full charge.<p>There are a couple...

Less expensive audio isolation transformers (such as the one from RS) do have the tendency to drop off at the high and low ends. You know, one of the things you might want to try is to build a preamp/buffer (as simple as using a dual audio quality op amp to create two voltage followers for impedance...

The latest issue (July 7) of Design News (one of the best free-distribution engineering trade magazines) has an article talking about your question -- "Hands-On Review of Microcontroller Development Kits". Without giving things away, I can say that they have a lot of good things to say abo...

To paraphrase the Oracle,<p>"What's really gonna cook your noodle is when you ask yourself why people answer them..."<p>By the way, when you use a "Y" from the line out (nominal 1K ohm) to two line loads, you have in effect a 500 ohm load. The impedance mismatch will mean that yo...

I believe you generally use a ground loop isolator audio transformer for this problem. I think Radio Shack sells one for $14.99 (270-054). You just plug the line out RCA plug in on one side, and plug the line in RCA plug on the other. Self-powered, simple, and you'll probably get real good results. ...

The Analog Devices AD210 is a potted epoxy package 2.1" X 1.0" X 0.35". If you've got one, save it -- you never know when you'll need it!<p>Russ is right. The least expensive method of analog optocoupling is simply to mix a bias current for the LED of a 4N28 or other optotransistor, s...

By the way, Chessman's idea is not insanely complicated -- it's been done and it's on the shelf, except that instead of an optocoupler, it uses modulated/demodulated transformer isolation (which also, incidentally, provides an isolated +/-15VDC supply along with the signal). It's called the Analog D...

You're talking about optocoupling an audio signal (line level), right? A couple of questions:<p>1) How much do you want to spend?<p>2) How much distortion are you willing to live with? Is DC voltage important, or only the AC signal?<p>3) What's your upper and lower cutoff frequencies?<p>There are a ...

I'll second Will's opinion on this post, especially the part about being off-topic. This is not a newsgroup, and we don't need or want filters.<p>The author of the post should go to<p> Google alt.politics.economics newsgroup <p>where his opinions will be right at home.<p>[ July 10, 2003: Message edi...

<Quote> "...with 90 volt l5 amp rating..."<p>By the way, is this an 0.5A, 1.5A, or 15A motor? I think you've got a typo -- "L5"?

Permanent magnet 90VDC motors are usually driven from DC motor drives, sometimes called SCR drives. These commercially available motor drives typically have speed control through a potentiometer which is either mounted on the enclosure or, for "open frame" drives, is connected at the termi...

desterline has a good idea. You're already familiar with the 555; you might want to start with a standard 20 microsecond one-shot with a CMOS 555. Let's assume a regulated 5VDC supply. If you load the output pin with a 40K resistor in series with a 10K pot, you can adjust the wiper of the pot to giv...