Source for Telephone DTMF type Chips ???

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ReadyKW
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Source for Telephone DTMF type Chips ???

Post by ReadyKW »

Does anyone know of any distributor of telephone decoder chips? Something like the MT8870 and in single unit quantities suitable for a hobbiest to play with. If these are not available, what are people using to communicate over the phone lines these days? Generating DTMF is somewhat easy, but the decodeing side is a little harder. I was hoping to find some sort of PIC routine but nothing immediatly pops out when I try an internet search.
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Externet
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Re: Source for Telephone DTMF type Chips ???

Post by Externet »

- Abolish the deciBel ! -
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CeaSaR
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Re: Source for Telephone DTMF type Chips ???

Post by CeaSaR »

This link popped right out on my Yahoo! search for MT8870.

CeaSaR
Hey, what do I know?
ReadyKW
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Re: Source for Telephone DTMF type Chips ???

Post by ReadyKW »

Thanks for the link to Tayda Electronics. I was hoping for something in the US, but I guess that is a pipe dream these days. Where did all of our Electronics distributors go? I also saw the link for a project that uses the chips and thanks for that reply. But my intent was to buy just the single chips and experiment with them. It would still be interesting to see if a PIC can reliably detect a touch tone and not voice. Thanks again for the quick replies.
dyarker
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Re: Source for Telephone DTMF type Chips ???

Post by dyarker »

...what are people using to communicate over the phone lines these days?"
What kind of information are you trying to pass over the phone line?

At 70mSec minimum per tone, plus a bit of silence between tones, you'll be lucky to get 10 tones per second. At 4 bits per tone (16 combinations of row and column tones), that's 40 bits per second. And, before you hook anything to a phone line you'll need a DAA (for isolation, current loop for off-hook, and ring detector).

MODEMs are cheap, the lowest speed (300 bits per second) is lots faster, and they have the DAA built in.

Cheers,
Dale Y
Engineer1138
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Re: Source for Telephone DTMF type Chips ???

Post by Engineer1138 »

Are you still looking? I may have a few SSI202 DTMF decoders if you're willing to pay a few bucks for shipping.

PM me and I'll check my storage area.
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