DTMF 8870 decoder from NOKIA 3310 - Page 2 - Electronic Circuits Projects Diagrams Free

aljamri · 1st October 2006, 12:27 PM

hello everybody, again im here asking for help again, i could not find the recomended crystal oscillator for this project (3.579545 MHz). is there any alternative to this ?

Thanks

**Nigel Goodwin** · 1st October 2006, 12:46 PM

Quote:

Originally Posted by aljamri

hello everybody, again im here asking for help again, i could not find the recomended crystal oscillator for this project (3.579545 MHz). is there any alternative to this ?

Assuming this is for the DTMF chip?, it obviously has to be exact - as everything is derived from the crystal. It should be available from sources that stock the chip, or you may need to have one made.

mramos1 · 1st October 2006, 01:02 PM

The 3.58Mhz xtal is old but around. It was used for color burst in TV.

Here is am 8870 schematic, the first gif.

ftp://members.aol.com/pdrunen/schematic/

EDIT: gif2 is closer to what you want. Also, that is a crystal, you called it an oscillator, that is why Nigel said you can build one.

**Nigel Goodwin** · 1st October 2006, 02:46 PM

Quote:

Originally Posted by mramos1

The 3.58Mhz xtal is old but around. It was using as for color burst in TV.

Right, if that's an NTSC colour crystal they are fairly easily available in Europe, even though not really used over here.

HarveyH42 · 1st October 2006, 02:48 PM

Could you post a schematic when you are done? I'm sure there are a few muslims that would love this circuit... (sorry, about that

)

Actually, I work irregular hours and it would be great to dial up the home phone and turn on/off stuff. Mostly I'd like to control some of my home security functions remotely. Like arm/disarm the alarm and select which cameras are being recorded.

Sorry about the terrorism crack, but I got razzed pretty good last month for helping on a robotics project, that some people though was inappropriate. I thought it improbable that it would never be built (time, money, and practical function), so I outlined the various sub-systems that this guy would need to develop, then all hell broke loose.

mramos1 · 1st October 2006, 03:20 PM

HarvyH42, I put a link three post up to a couple 8870 schematics.

audioguru · 1st October 2006, 03:38 PM

Quote:

Originally Posted by HarveyH42

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.

HarveyH42 · 1st October 2006, 04:02 PM

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.

audioguru · 1st October 2006, 04:11 PM

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.

mramos1 · 1st October 2006, 04:25 PM

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.

electromania619 · 9th March 2008, 01:47 PM

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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1st October 2006, 12:27 PM	(permalink)
aljamri	Please helpl my again hello everybody, again im here asking for help again, i could not find the recomended crystal oscillator for this project (3.579545 MHz). is there any alternative to this ? Thanks __________________ Its what your friend in Your mind, what you in your friends mind

1st October 2006, 01:02 PM	(permalink)
mramos1	The 3.58Mhz xtal is old but around. It was used for color burst in TV. Here is am 8870 schematic, the first gif. ftp://members.aol.com/pdrunen/schematic/ EDIT: gif2 is closer to what you want. Also, that is a crystal, you called it an oscillator, that is why Nigel said you can build one. Last edited by mramos1; 1st October 2006 at 03:21 PM.

1st October 2006, 02:48 PM	(permalink)
HarveyH42	Could you post a schematic when you are done? I'm sure there are a few muslims that would love this circuit... (sorry, about that ) Actually, I work irregular hours and it would be great to dial up the home phone and turn on/off stuff. Mostly I'd like to control some of my home security functions remotely. Like arm/disarm the alarm and select which cameras are being recorded. Sorry about the terrorism crack, but I got razzed pretty good last month for helping on a robotics project, that some people though was inappropriate. I thought it improbable that it would never be built (time, money, and practical function), so I outlined the various sub-systems that this guy would need to develop, then all hell broke loose.

1st October 2006, 03:20 PM	(permalink)
mramos1	HarvyH42, I put a link three post up to a couple 8870 schematics.

1st October 2006, 04:02 PM	(permalink)
HarveyH42	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.

1st October 2006, 04:11 PM	(permalink)
audioguru	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. __________________ Uncle $crooge

1st October 2006, 04:25 PM	(permalink)
mramos1	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.

9th March 2008, 01:47 PM	(permalink)
electromania619	dtmf 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...........