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Jberryman

Inductive Telephone Tap Plans

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Great post!

I believe I might just make one of these, because I'm bored.

I think I actually have a ferrite core laying around... from my digital camera box :blink::blink:

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Great post!

I believe I might just make one of these, because I'm bored.

I think I actually have a ferrite core laying around... from my digital camera box  :blink:  :blink:

If you have an AC current clamp you can use that, too. You may want to wrap the ring lead around

the pickup a few times (most are 1000:1, and you probably want to reduce that a bit depending

on the impedence you want to match to your amp).

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That was a very well done web page/project, and an inductive coil pick-up can be used for other things besides electronic surveillance, as it will pick up any electrical field in general. I'm sure you noticed that when you brought it near a computer monitor or flourescent light.

And for those of you too lazy to build one, Radio Shack still sells the inductive pick-up coils:

http://www.radioshack.com/product.asp?cata...t%5Fid=44%2D533

The Radio Shack portable amplifier, Cat# 277-1008, is a must-have piece of equipment for anyone's kit.

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What a coincidence! I just bought one of those last week from radio shack! I have a digital recorder that I use it with. I usually record stuff from pay phones. Mostly DTMF tones that are used by the pay phone to call operators and other interesting stuff. Its a good tool to have around.

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The Radio Shack portable amplifier, Cat# 277-1008, is a must-have piece of equipment for anyone's kit.

Or, for the old school, a WECo 147C amplifier (or for the really old school and that beautiful

22.5V battery, vacuum tube sound, a WECo 147B). Extra points if it says "bell system propery,

not for sale" on it.

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I just built one of these babies per the instructions posted. It works pretty nicely; audio is very clear although there is a bit of noise which could be from my lousy connections or any number of things. You could decode DTMF from this no problem.

Just for the record: I used 30 gauge wire because the radioshack part that was cited is actually a threepack of wire, none of which are 28 guage as I found out when I got the package. Also the ferrite core that he uses no longer exists with radioshack, so I bought a core from mouser electronics: part no. 623-0443800506 (it may just be 0443800506).

A note about that core: before you snap it together, snip off some of the lip on the two latches that hold it closed. I closed it and couldn't for the life of my get it apart. had to cut the hinges.

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Please forgive me for refuring back to the old school "Phreak box" names... But is this what was called the "infinity tap?"

-Dr^ZigMan

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Please forgive me for refuring back to the old school "Phreak box" names... But is this what was called the "infinity tap?"

-Dr^ZigMan

The term "infinity transmitter/bug" is not an old-school phreak term. That's what surveillance operatives and equipment suppliers actually called them back in the day.

An "infiinity transmitter" or "harmonica bug" was a dial-in room bug that dates back to the 1950s and 60s. One would install this device at the target's residence on their phone line, and activate it by calling into it and sending a signalling tone (often generated by a harmonica) down the line. You could then hear everything in the room where the device was installed.

Step and crossbar switches enabled the voice connection on the local loop before the called party picked-up, so it was often possible to have this thing pick up before the target's phone even rang. Otherwise, the surveillance operative just said "sorry wrong number", and waited until the called party hung up to activate the device.

There were even ones designed for ESS switches in which the operative did have to wait for the called party to pick up in order to activate the device.

The big problem with the device was that if the target picked up the phone to make a call, they'd notice a problem.

There were kits available in the 1980s/90s for a similar device that you could call and it would automatically pick up and send room audio down the line. Some answering machines also had a feature to do so. The old high-end Panasonics did.

The vehicle emissions stations of a now-defunct inspection program in a New England state used that particuar Panasonic model to provide call-in information for customers. They simply plugged them in, set them to "announce only", recorded the announcement message, and never changed the access code from its default...

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There were kits available in the 1980s/90s for a similar device that you could call and it would automatically pick up and send room audio down the line. Some answering machines also had a feature to do so. The old high-end Panasonics did.

I had an old Bell (Southwest Bell I think) answering machine which would do this. It worked quite well. It also had a function to automatically forward messages to another number. You could, for example, go on vacation and set it up to call you after X amount of new messages, at which time it would call the target number you programmed and ask for the code before playing the messages. I tested it out with a friend... but unfortunately forgot to turn off the feature, so it called his house all day after each message! Wish I still had that answering machine, as I had forgotten all about those features. :(

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