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DTMF 8870 decoder from NOKIA 3310

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HarveyH42 said:
I'm sure there are a few muslims that would love this circuit...
They don't use remote, they like to blow themselves up and everybody nearby.


Will give #2 a try. I scrapped an old color tv a while back, maybe I'll get lucky on the crystal. I was going to us LM567 decoder, but it seems that you need one for each button you want to decode.

Audioguru: I agree that the bombers are mostly low tech, why spend the time/money building a fancy bomb, when there so many willing volunteers to do the job. The 9/11 terrorists didn't build anything, just got into flight school. Never came out, but suspect that they got a student loan from the government, our government.


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DTMF uses two frequencies so two LM567 ICs are needed to decode each button, until other buttons share the same frequencies.

In the '80's, DTMF decoder ICs were rated for "talk-off", which is how many times they wrongly decoded speech as DTMF when a test recording was played. I trhink the LM567 system would fail miserably.


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I still like the pic version I posted a link for in post # 4 of this thread.

If the fellow was in the US I would mail him a couple 3.58Mhz, I have them here.


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I'm trying to connect the mobile earphone wire into the decoder input terminals, and I'll put my mobile on auto answering mode ( after 3 rings) then I'll press the numbers of my mobile to give beeps, is that signal clear and strong enough to be decoded or not? please help me with ckt.tell me wat 2 do futher...........


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DTMF with 8051

Even with the 4 bits from the DTMF decoder, you will need to read them and have a processor deal with them, if you are doing real control apps.
Also have an interface to the decoder chip.

Is this is a school project? Maybe just light up 4 LEDs.

So you are in the 6th grade? Wish my kids here in the US were doing electronics in the 6th grade. I have scopes, just sold my 8051 emulator.
PICs and Atmel chips and programmers all over..

They like sports and video games. I will fix the video game part soon though.. Too many hours wasted.
Can you give me a basic flow of DTMF decoder(MT8870) with 8051 microcontroller??

How it works??
and necessary steps for caller id provision..
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