CircuitMan

Anyone got a good circuit for a bug/mobile detector. Basically rf signal detector, help me please ops: ops: ops:

audioguru

If you don't specify a band of frequencies, it will pickup every radio or TV station, taxi or police car etc. in town. Of course, instead you could make an "all frequencies" bug detector have a very low sensitivity. Then it won't pickup the bugs unless it is very close to them, or the bugs broadcast a powerful signal (unlikely).

zachtheterrible

heres a circuit that you could use. you could adjust the sensitivity by adding a little transistor amplifier to it. ask someone else about that cuz i dont have a clue. i think that you could probably get it to sniff a bug within 10, maybe 20 feet without picking up other signals (unless of course you have a wireless intercom or something). im totally guessing though. make sure u keep that capacitor in there. i think its there so that it wont pick up mains electricity.

the dvm + n - go to a voltmeter (i recommend a digital one), and the ground is supposed to be connected to the thing that you're testing, but obviously you cant do that because you are looking for the transmitter. but you dont have to do that, doing that just increases the sensitivity. here it is:

Attached Images

simplest_rf_probe_101.gif (6.7 KB, 807 views)

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CircuitMan

I want something like this:

http://www.globalgadgetuk.com/detector.htm

more infor needed! ops:

audioguru

It is obvious that with such a high price, that detector must have many, many parts and is probably too complicated to make yourself.

CircuitMan

Ok yeah but I want a simple version of this forget all the other bits like lights sound i just want the detection part!

jrz126

Those extra bits are the simplest things on there, the detection is super complicated.
Cell phones use a wide range of frequencies, so it's definitly not an easy answer.

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Jeff Zimmerman
To the optimist, the glass is half full.
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timothyjackson

Hello Circuitman

have a look at:

http://www.pemburyonline.com/product...tector_pen.jpg

You could buy one, take it apart and understand it that way.

Take care

Timbo

AndyWatson

I recently built a RF detector device, complete with Basic Stamp, LCD display, 2-stage LNA amps, selectable filters, mixers, microprocessor-programmed frequency synthesizer for generating the LO, an RF detector, and a directional antenna. You can select narrow or wide bandwith (5 to 20 MHz) and any frequency from 750 to 1800 MHz. It's got really good sensitivity and can pick up cell towers from several miles away. The entire package cost around $800 and took about 6 months to develop. Unless you have alot of time and expertise, I suggest you buy a commercial device.

zachtheterrible

Wut about that circuit I posted? I think he just wants to pick up bugs, and that would work pretty nicely if a little amplifier was added to it right? Then you just adjust the sensitivity of the amplifier. Just get a high speed diode tho :lol:

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CircuitMan

I want to pic up mobile phones, dont care about bugs or other radar gear.

I found something good:

http://www.elektor-electronics.co.uk...oj/frmipro.htm

Not sure if this will work as it looks cheap, need to modify it someway so that i can get output as a light and sound no headphones. :?

jrz126

that might do what you want, but it probably wont work as good as that other one.

here's a better url for it http://www.elektor-electronics.co.uk...d/010128uk.pdf

__________________
Jeff Zimmerman
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

zachtheterrible

Oh

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I'm no electronics god, i just talk too much.