Telephone Surveilance Bug Circuits
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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.... -
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. I do however, receive many requests for a higher powered circuit and.... -
Here is a simple yet very useful circuit which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important feature of this circuit is that the circuit derives its power directly from.... -
FM Telephone 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... -
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... -
If you ever wondered how those phone bugs from spy movies work, here is the schematic for your very own. This simple FM transmitter uses a phone line to both power the device and receive the audio signal. Just hook it up to the phone line you want to monitor.... -
A simple telephone transmitter circuit that is ideal for transmitting the telephone conversation through small distances. The circuit is very simple and uses only few components. The entire circuit can be easily included in the telephone itself or in the.... -
Small telephone bug. Listen telephone line on your FM receiver. It is self powered. Small part count. Circuit diagram, schematics, electronics project.... -
A very simple telephone broadcaster or transmitter which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important feature of this phone transmitter is that the circuit derives its....
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New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
Beeper and/or LED remotely-operated via mains supply line. Pressing the pushbutton of the...
A simple bridge rectifier and a 12-V regUlator powers the MOSFET sensing circuit. The unregUlated...
This system uses an MM5369 IC to derive a 60-Hz signal from a TV burst crystal (3579 MHz). F8...
This Bat Detector Circuit is authored by Chris Eve. Basic tests with a variety of salvaged...
In the circuit below, a quad voltage comparator (LM339) is used as a simple bar graph meter to...
Thanks to Don Klipstein ( don@misty. com ) for his comments and additions to this document. His...
Similar to the CMOS based Touch Switch also on this site, this transistor based touch switch can...
This page describes how I have modified my SkyWatcher dual axis EQ5/EQ4 motor controller to allow...
WB5LUA described GaAsFET preamps for several microwave bands which included an active bias...
When a key is pressed the remote control sends a preamble followed by 32 bits of information...
A circuit diagram of the control when the input line is high time, 4016CMOS analog switches will...
As shown for the low-frequency output 7W power amplifier circuit. The circuit uses a FET input...
As shown in FIG To eliminate hum instrument amplifier circuit. FIG amplifier stage A1, A2...