Anybody want to bet a beer that he'll never be back again? Another one for the googlegroupie bin, I fear.
Cheers! Rich
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The PIC 10F200 series have a 1% internal oscillator which should be good enough, cost is around 50 cents in volume. Add an RC filter to the PWM output and you have a three component soution for under $1.
Dave :)
How about building an electrically sustained thumb piano? Little piece of spring steel cut to length and sitting over some sort of magnetic transducer that couples it to an oscillator circuit. Optionally run it on an overtone and divide if a piece resonant at 200hz would be too big. With luck you'd only have to tune it for each batch of steel, and not each individual piece.
The cheapest solution would be a small PIC or Atmel microcontroller with on chip oscillator and building a "magic sinewave" as in Don Lancaster`s cmos cookbook as some others already mentioned.
-- Dipl.-Inform(FH) Peter Heitzer, peter.heitzer@rz.uni-regensburg.de HTML mails will be forwarded to /dev/null.
Tell us more about the headphone. Can it have a resonant piezoelement in it?
>-- -- kensmith@rahul.net forging knowledge
That depends on how many you are making. If you have to provide 1 to every person on earth, a custom IC would be the way to go. It would take far fewer transistors.
-- -- kensmith@rahul.net forging knowledge
it seems to me that the magic sequence pwm method is the best. if I sample a 200hz sinewave at 1MHz and turn it into a bitstream which matches an rc filter response, the results are very good (at least, eyeballing it in excel). This would only take 5000 BITS of storage, a
1MHz clock, and an rc filter, so its cheapy weepy. Okay, and now, I will cheat: I dont really need the 1Hz accuracy anymore. I originally thought I needed it because I have to have two tones seperated by a certain frequency which was only a few hertz to begin with. But the way I will implement this, with a parallel flash or eprom, will 'lock' the two tones together, so even if the clock is inaccurate, the tones will track each other because they will both experience the same error from the clock. So now the solution is:cheap 16kbit (or whatever size, only need 10kbit) parallel eprom/flash (whichever is cheaper)
1MHz RC oscillator (few passives and digital gate) RC output filterthe tones (200hz/210hz) will each be sampled at 1MHz and encoded into a bitstream which takes into account the response of the output rc filter, to reproduce the tones. the bitstream will be burnt into the eprom, into the upper or lower two bits (or whatever two bits) of each byte, so that clocking the eprom data out will simultaneously clock both tones out.
tada!
i assume in 100k+ quantities this will be less than 1$
oh and sorry for totally changing the requirements.
schreef in bericht news: snipped-for-privacy@j52g2000cwj.googlegroups.com...
Stuff a little dual DDS in one component, PIC10F202, sot23.
-- Thanks, Frank. (remove \'q\' and \'.invalid\' when replying by email)
If that's what's needed then a dog simple 205Hz oscillation, AM modulated by 5Hz, will produce the two tones cheaply.
I'll bite: So, what's a chaep, simple way to generate 205Hz sine waves?
A 205Hz sine wave oscillator ?:-)
...Jim Thompson
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It\'s what you learn, after you know it all, that counts.
Correction; a _chaep_, _simple_ 205Hz sine wave oscillator. ;-)
-- Keith
Rather than 'chaep', how about chap chae?
Best regards, Spehro Pefhany
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Things are simplified greatly by using a 205Hz square waveform to modulate a 5Hz sine waveform by +/- polarity switching- then LP the resultant. See National LB-16 for a way to produce stable low frequency sines.
Ummm, best similar approach is divider for 200 HZ square wave, feed to integrator to get triangle, feed that to diode wave shaping to get sine with < 1% distortion. Be careful there are a few gotcha's with this approach.
-- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
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