Author Topic: FM radio phone bug  (Read 2532 times)

Offline Alpha Omicron

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FM radio phone bug
« on: November 26, 2006, 04:07:16 PM »
http://leoricksimon.blogspot.com/2006/04/telephone-fm-transmitter.html

Transmits audio from telephone at FM frequency. Parts list and circuit diagram included.

Offline legend813

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Re: FM radio phone bug
« Reply #1 on: November 26, 2006, 06:54:31 PM »
Subject to major freq drift due to power level, temp etc etc.... Use the guts from a baby monitor.

Offline scotttherobot

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Re: FM radio phone bug
« Reply #2 on: August 20, 2007, 08:29:58 AM »
Use the guts from a baby monitor.

Ohh! Do tell! Is there a circuit somewhere? If not, i think i could manage making one with an audio transformer from radio shack, but how do you keep the phone co. from seeing an extension as off hook? OH! nevermind. wrap a ferrite with copper and clip that on to one lead of the phone wire. You would never even know it was there due to no voltage drop, etc...

Offline MadManMarkAu

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Re: FM radio phone bug
« Reply #3 on: August 20, 2007, 08:55:51 AM »
As long as you use a high impedance audio transformer coupled to the line via a couple of 200V+ non-polar caps, there should be no change detectable on the line.

That reminds me, there used to be an old number you could call... I think it was from panel-office served phone lines, what you could call and it would drop your line from the exchange for a minute or so. Great to test for phantom devices attached to your line (line-to-line resistances and capacitance changes)

Offline scotttherobot

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Re: FM radio phone bug
« Reply #4 on: August 20, 2007, 10:44:28 AM »
sorry for my last post, i was in a rush to leave. Here is a link to the type of tap i was trying to explain. Just wire in in place of the microphone or in parallel with a switch, and you have room and phone monitoring.

http://www.unterzuber.com/tap.html

(sorry, i dont know if thats a website you guys dont like- i just found it on google)

As long as you use a high impedance audio transformer coupled to the line via a couple of 200V+ non-polar

Do you have a circuit diagram? A link even? Thanks