July 11, 2009 AT 3:33 pm

Electromagnetic Field (EMF) finder (DIY bug detector)

3230858319 99F9279906 B
Electromagnetic Field (EMF) finder

This is very simple EMF detector. Modified (by Melih Karakelle) from here. Two Schottky diode (BAR10, 1N5711, etc.) for rectifier, an Op-Amp (LM10), a cap (100 nF), a resistor (1 Mohm), triger level adjust trimpot (220 Kohm), a driver transistor (BC550). Operated with 3 V battery (2 x AA). Very simple and working good. Can detect/find a cell phone (GSM) about 30-50 cm (when RF propagation), electricity cable (on load), tv/monitor etc…

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  1. Yes! This is EXACTLY what I’ve been wanting to get/make for AGES! Thanks for posting this!

  2. Can this detect CDMA phone transmissions, too?

  3. Nice, you should definitely make a kit for this!!

  4. I would love a tutorial for this!

  5. If you set up a camera on a tripod and use long exposure or image compositing techniques, you can get an really cool effect by moving the sensor all over a room. You’ll end up with a visualization of the fields in the whole room.

  6. “Can this detect CDMA phone transmissions, too?”

    Yeah, if you place the device next to (12-18 inches) the antenna of the phone while it’s ringing or during a call. Any amplification would lead to unlimited false positives.

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