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Bugs (Electronic) & Detectors
Last Updated on: Monday, March 09, 2015 04:11 AM

Links to electronic circuits, schematics, designs for engineers, hobbyists, students & inventors:
3 Transistor FM Radio Bug -  Electroinic circuit design…. [from Harry Lythall's website]
3m 100 MHz small bug -  (circuit added 05/06/07)
Bug Detector (mini) -  This project is a handy piece of TEST EQUIPMENT. You can never have enough assistance when designing FM bugs.  The first thing you need to know after putting a bug together is the fact it is transmitting.
This project gives you this indication. Once you know a bug is transmitting, you can work on getting the best output power and adjusting the frequency to a blank spot on the dial.  (schematic added 04/09)
Bug Detector with Beep -  This circuit is not open for discussion. Although working perfectly, it was experimental. I will answer no emails in regards to this circuit.  If you are looking for a more serious and reliable bug detector, …. [Tony van Roon's circuit]

Crystal Locked FM Bug -  Producing a crystal locked transmitter is a natural extension to our FM Bug series.  We have already produced a number of simple FM devices, (without the use of a crystal) and showed how the power and frequency depends on a number of factors including the voltage of the supply and the design of the stages. (electronic circuits 04/09)
Electronic Eavesdropping Devices Detector -  Copyright of this circuit belongs to smart kit electronics. In this page we will use this circuit to discuss for improvements and we will introduce some changes based on original schematic…..(design idea circuit added 09/08) [Site is underconstruction right now]

FM bug -  Schematic only, no circuit description
FM Telephone Bug -  Would you like to be able to amplify a phone call so everybody can hear it? Or perhaps you'd like a way to record phone calls for record-keeping purposes. If either idea sounds good to you, then you might want to build the FM Telephone Transmitter describe in this article. It's a simple, yet ingenious device that connects in series with a phone line, "reals" power from the latter, and transmits both sides of a conversation to an FM radio tuned to between 90 and 95 MHz.…. [Tony van Roon's circuit]
FM Telephone line Bug Transmitter (Aaron Cake) -  (circuit / schematic design added 7/03)
FM Transmitter Bug -  This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The coil.... [by David Sayles]
High Power FM Microphone FM Bug -  My FM Wireless Microphone has been a very popular project with beginners and experienced constructors alike. It has been used inside guitars and as the basis of a remote control system. …. [from Harry Lythall's website]
Infinity Bug -  This project requires a high degree of soldering. It uses surface-mount resistors, capacitors transistors and diodes.  It can only be assembled on the PC board supplied…(circuit 02/07) 
Miniature FM Spy Mic -  This spy mic works from single 1.5 volts AA type battery cell. It is highly sensitive and has a range of 300 meters. You can use any HF transistor with cut-off freq. >300 MHz for Q. Use electret mic.  (added 6/06)
Simple Phone Tap -  Will record any conversation on any ph1-on same line, the circuit seems to be a bad design because it does not provide proper isolation and has too low DC impedance (can keep you line off-hook all the Time) (added 5/02) [Aaron Cake's design]
Surveillance Transmitter Detector -  This circuit can be used to "sweep" an area or room and will indicate if a surveillance device is operative. The problem in making a suitable a detector is to get its sensitivity just right, Too much sensitivity and it will respond to radio broadcasts, too little, and nothing will be heard. [Andy Collison]
Telephone Listening Bug -  Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet. It is extremely easy to build and is therefore a good, useful beginner project. ….(design added 11/08)
Three Transistor FM Radio Bug -  Electroinic circuit design…. [from Harry Lythall's website]
Vibrating pocket bug detector -  (schematic / circuit added 08/08/08)
VXO FM Bug -  After constructing my Solar Powered FM Bug circuit, I decided to try building an FM bug with a more frequency-stable oscillator. Numerous Variable Crystal Oscillator (VXO) circuits have been published for ham radio receivers and transmitters, these are normally used for fixed frequency CW applications. I decided to see if it would be possible to use a varactor diode (voltage variable capacitor) to modulate the frequency of a crystal oscillator with an audio signal.... [G. Forrest Cook]
Wireless Telephone Bug -  Here's a neat little project that will allow you to monitor your phone line as soon as your phone is off hook. You can use a regular FM broadcast band radio to monitor the conversation. Just remember, it ….(Circuit design added 03/08)
Wireless Telephone Eavesdropper Electronic Circuit -  The IR transmitter connects to a telephone circuit, and transmits both sides of all telephone conversations to any line-of-sight location, within 40 feet. No power is taken from the central office, as long as all phones remain on-hook. The current flows through the phone and back to the central office....(electronic design added 6/07)

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