38.4kHz crystal

555s for Dummies? ;-D

Cheers! Rich

Digikey and Mouser are out of reach for me, although they do come in useful for reference at times just like this. And I haven't found a source for 38kHz crystals in India, not even at the Indian branch of Farnell. But 38.4k _is_ available and, by the light of this thread, it doesn't seem to be in danger of extinction.

That's an excellent suggestion (it covers nicely the recent dearth of colorburst-frequency crystals). The use here is for IR remote senders, and a takeapart of a remote reveals (first remote that I could get my hands on) a ceramic resonator at

400 kHz. Ceramic resonators are cheaper and more rugged than quartz. Also, cheaper.

Signetic's 555 book?

--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
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"Spehro Pefhany" schreef in bericht news: snipped-for-privacy@4ax.com...

There are some already, for instance:

555 Timer Applications Source Book: With Experiments (Blacksburg continuing education series ; 21538) by Howard M. Berlin (May 1979) 555 Timer and Its Applications by M.C. Sharma (Dec 1, 2008) Integrated Circuit 555 Projects (Bernard Babani Publishing Radi) by E.A. Parr (Paperback - Feb 28, 1978) ENGINEER'S MINI-NOTEBOOK 555 TIMER IC CIRCUITS; CAT NO. 276-5010 by Forrest M. Mims III (Paperback - 1989)

If you want a real thick book, collect all the 555 circuits on the net. But writing a new one...

petrus bitbyter

And, a little worse frequency spread.

Grant.

Compiling all the _good_ 555 (or otherwise) circuits on the net would be a lot more work and would yield a much thinner book.

Best regards, Spehro Pefhany

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Then compile the worst you can find, and use them as examples of what not to do. We could rate them on a scale of 1 to 100 Slomans. :)

--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.

"Spehro Pefhany" schreef in bericht news: snipped-for-privacy@4ax.com...

Sure. That why a did not mention the doubles and left out _good_ :)

BTW. It has been at least twenty years that I did my last design using a

555. Though I did not look for it, I'm pretty sure it was re-invention rather then completely new. These days I'd use a small micro like an 8-pins PIC for it. Nevertheless, a 555 still has it's use so I expect it to be used - and misused - for several years to go.

petrus bitbyter

Proof that the 555 was a toad was that the first three generations of users all got warts.

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IIRC the clock/freq reference for IR remote controls is usually provided by a ceramic resonator or divided down from the MCU clock.

And higher tempco.

--
Yup, but in this case it seems the OP wants to generate the carrier
directly from the crystal fundamental without having to divide down.

That's right. I've been using RC oscillators to generate the

38kHz signal directly with $0.12 CMOS chips. The same chip also does other functions and it works well in the prototype as well as a (very low-volume) trial production batch. Using standard logic ICs obviates the need for programming, and a crystal will do away with the need for initial adjustments with minimal change in the circuit and PCB designs.

Agree with both statements. But many (most?) IR carriers, including mine, don't need tight frequency control. Standard IR receiver modules are tuned broadly enough that a spread of +/-1% is quite good enough. In fact, when my frequency meter was temporarily out of service, I successfully ran tests at carrier frequencies which later turned out to be as much as 5% off. A ceramic resonator is more than good enough, but is no easier to get than crystal at the frequency I need.

Where you are crystals may well be more available or cheaper, back when i was futzing with IR remotes i used ceramic resonators, cheap and readily available and equivalent crystals were rather more expensive.