Surveillance Circuits
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It is a simple and reliable system for processing human speech. It has the task of altering the tone of the human voice and making it heard as artificial, such as the voice of a robot that, as it is known, is produced by artificial means. This is an easy but.... -
CI and LI resonate on the 1750 meter band, with coverage from 150 kHz to 500 kHz. LI can be slug-tuned for 160-to-190 kHz coverage alone or a 2.5 mH choke can be used for LI, if desired, using CI for tuning. A 1N270 germanium diode rectifies the RF signal.... -
The bug tracer is made up of a simple rf-injector circuit consisting of Ql and Q2, and a pocketsize, AM broadcast receiver. The two-transistor rf-injector circuit supplies a constant rf signal to one end of a cable. Then the AM receiver is used as a.... -
This rf detector can locate low-power transmitters (bugs) that are hidden from sight. It can sense the presence of a 1-mW transmitter at 20 feet. which is sensitive enough to detect the tiniest bug. As you bring the rf detector closer to the bug, more and.... -
Door open alarms are used chiefly in automotive, industrial, and appliance applications. This type of circuit can sense the opening of a refrigerator door. When the door opens, a triac could be activated to control the inside light. The figure shows a door.... -
LDR1, a cadmium sulphide (CDS) photoresistive cell is used as the lower leg of a voltage divider between Vcc and ground. The timer terminals 2 and 6 are connected to the junction of the photocell and SENSITIVITY control Rl. The resistance of the.... -
This circuit responds to RF signals from below the standard broadcast band to well over 500 MHz, and provides a visual and audible indication when a signal is received. The circuit is designed to receive low-powered signals as well as strong sources of.... -
Circuit principle: OV9650 processor interfaces include three parts SCCB interface, data output interface and control interface. SCCB interface to play the role of transfer prov.. -
The Wireless Keylogger consists of two main building blocks: the transmitter, and the receiver. The actual keylogging takes place in the transmitter, which is in fact a PS/2 hardware keylogger, with a built-in 2.4 GHz wireless module. Captured keystroke data.... -
The circuit shown below is a basic latching circuit consisting of a quad 2-input NAND Gate IC. It is configured such that the flip flop circuit U1A and U1B has both its input held at logic "1". Pin 1 is held at logic "1" by the magnetic contact and pin 6 is.... -
This bug can be attached to anything from a glider to a pot plant and you can track it with a radio. Why track a pot plant? The Beeper is the result of many requests for a mini tracking device and introduces a new world of tracking. The circuit is very.... -
The circuit consists of three stages, an electret microphone, an audio amplifier and an RF oscillator. The electret microphone consists of only two parts - a FET transistor and a plastic diaphragm. There is nothing else inside the case. The 3-leaded FET has.... -
Is a 100 to 200 metre (100 to 200yds) device having a very stable performance. It can be used as a hand held microphone or left on a shelf to pick up the sounds in a room. It has many interesting features. These will be fully described in the article. One.... -
The RF oscillator using the inverter N2 and 10.7Mhz ceramic filter is driving the parallel combination of N4 to N6 through N3.Since these inverters are in parallel the output impedance will be low so that it can directly drive an aerial of 1/4th wavelength..... -
This circuit is a simple two transistor (2N2222) FM transmitter. No license is required for this transmitter according to FCC regulations regarding wireless microphones. If powered by a 9 volt battery and used with an antenna no longer than 12 inches, the.... -
This circuit uses a small microphone to capture the sound and some transistors to generate radio waves that can be picked up by a FM receiver like a car stereo. The first part is the microphone and some resistors to get it working. Next we have a capacitor.... -
Many times exists the need recording some conversations from a telephone line and this it's relatively easy. If we want however to have the possibility recording from two telephone lines simultaneously in a tape recorder, we needed a circuit as what appears.... -
The GLMDA is designed to detect the motion of a human or animal both in daylight and at night and to provide a normally open relay output that can be used to activate many types of loads. The GLMDA also has terminals for connecting an optional photocell.... -
The video switcher described here can display the output of two, three, or four cameras on a single monitor. The number of cameras is set by a DIP switch on the circuit board. That feature avoids blank displays if less than four cameras are used by.... -
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, go to the Countersurveillance Monitor article on.... -
This Mini FM Bug Detector is basically a broad-band receiver. It picks up the complete band from below 80Mhz to 150MHz and almost anything that transmits in that band will be detected. If a bug with a sensitive microphone is transmitting nearby, the result.... -
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.... -
someone here have wired up a spy 5000m to a F2 whit the remote start ? mine keep blowing the start fuse. Red - Positive baterry Black - Negative ... -
Sorry, it seems that the file you`re attempting to access no longer exists! The file may have been renamed or removed from the archive. Please use the navigation links on the left to browse the area of the archive you`d like to visit. You are connected to.... -
signal detector electronics that can be used to detect the signal does not AF / RF. This series is very neat and easy to make... -
Take a look at this fm spy transmitter which can be used as a bug transmitter or as diy fm bug too. It uses a single IC 74F13, one coil, a capacitor, one t... -
The circuit was constructed using a few components that is powered by a 9 V battery for sensing the presence of bugs transmitting within the frequency mod... -
Here we`ll discuss how to make an electronic spy bug circuit using two methods, one that consists of wire link from the transmitter to the receiver, and the other which is completely wireless and can be used to eavesdrop a particular conversation over a.... -
Here is a very simple telephone broadcaster 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.... -
Here is a remote operated spy robot circuit which can be controlled by using a wireless remote controller. It can capture audio and video information`s from the surroundings and can be sent to a remote station through RF signals. The maximum range is 125.... -
This FM spy telephone circuit is mounted serial with the phone line. When is signal on the wires this transmitter will radiate airwaves thru the wires which act as antenna. There is no need for batteries because it got his voltage supply from the phone....
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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.....
Popular Circuits
This project and your efforts will provide you with a 0.55...3 watt input to easily 10 watt...
The design presented here works by applying a 50kHz, 200mV square wave to the capacitor under...
Continually monitors battery voltage during use and consumes only about 250 ? A (until the end...
This rf power switch operates at 1. 7 MHz with a 50-V source and load. Its on loss is 0.2 dB and...
The 20-W + 20-W stereo amp consists of two complete, separate 20-W RMS bridge-type amplifiers....
Temperature-indicator and temperature-based products have generated wide interest. There are...
We are surrounded by battery operated equipment of all kinds, and this array is growing still....
Using this design, you can construct an electromagnetically impulsed pendulum clock with a...
The switching power supply provides 12 volts, at 10 amps, maximum, using a discrete transistor...
This little circuit is invaluable for quick go/no-go testing of just about any remote control...
Most of the IR remotes work reliably within a range of 5 metres. The circuit complexity increases...
A sensor in garden railway applications. Hall Effect sensors are the electronic equivalent of a...
Thyristor zero trigger circuit output waveform is a sine wave, it will not produce as phase-shift...
This is a two-way can set the alarm circuit which uses a Schmitt IC, with responsive and sound...