Dual-tone Dialing

279

03:38:36

This circuit illustrates the principle of dual-tone (DTMF) dialing. The keypad is
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published 7 years ago

hurz

7 years ago

the relays are not need, not in simulation and also not in real http://everycircuit.com/circuit/4902699800461312

stanislav_maslovski

7 years ago

Indeed, I agree!

Karma247

7 years ago

👍

zorgrian

7 years ago

There is no spoon! (Neo the matrix, living in a simulated world) ... But in this case, i see no relays, so they must once have been here, and then were removed as per @hurz circuit?

zorgrian

7 years ago

Anyway, nice old style DTMF. In practice, this was done in software/ microprocessor, or dedicated chip that does additive frequency as result of 'dumb' keypad. This was preferred as, the signals do not then pass through switching matrix!

zorgrian

7 years ago

Theowners have downgraded the cloud service

hurz

7 years ago

zorg, that was also working long time before microprocessors were available.

zorgrian

7 years ago

Yes, as i said... Nice old style DTMF

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