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FM Telephone Bug


New Member
I've basically seen one circuit on the net that connects to a phone line and transmits phone conversations to a FM radio.

See Link: www.aaroncake.net/circuits/phonebug.htm

Some of the parts are hard to find (i.e. 1SS119 diode and 2SA933 transistor). Are there other parts that could replace these that are accessible from companies like Jameco, MCM, Radioshack?

Also are there any other bug circuits out there that some of you may know about?



Active Member
i dunno about the diodes, but im sure u could use just about any NPN general purpose transistor thats rated above 100 MHZ, like 2n2222, 2n3904, bc547, etc


Well-Known Member
Most Helpful Member
That project uses a PNP transistor, not an NPN as Zach thought it was.
A 2N3906 will be fine.


New Member
Re: Transistors

Thanks all,

Looking at the specs for 2SA933, I'll need to use a PNP transistor as you suggested, so I'll try the 2N3906.

In reference to the 1SA933 diode, I found a 1N914 diode, that is similiar to it. Both are "small signal, fast switching silicon diodes". I think the 1N914 will work; any objections?

I'm almost ready to build. I'll give feedback of the results.

Thanks Again


Active Member
Most of case i found in chinese phones 1N4148 in this position, but i always worry: the ringing signal is about 100V AC, the 4148 absolute max. forward voltage 100V! So i strongly recommend the 4002....


New Member
Aaron cake Telephone Bug

I'm confused about something. (Please see the link)

Link: http://www.aaroncake.net/circuits/phonebug.htm

In the notes, the last sentence in line 3 says, The green wire from OUT1 goes to the phone(s), as well as the red wire from OUT2.

What does this mean :? ?

I have a phone jack with the 4 wires exposed on the end (Red, Green, Black & Yellow). I know where the red & green wire goes on the circuit, but is a bit confused about the above statement.

Thanks for all replies. :)

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