Vacuum Tubes Valves
Musical & effects
Yagi Uda Antennas
Metal Detector Circuits
Liquid Sensing Circuits
Light Sensing Circuits
Voltage Detector Circuits
Air-Gas Detection Circuits
Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
Free Energy Circuits
AC to DC & DC to DC
Solar Cell Circuits
Micro Power Circuits
Switching Power Supplies
Light Laser LED
Digital to Analog
Analog to Digital
Data Bus Circuits
Voltage to Pulse
Current to Voltage
Frequency to Voltage
RF Converter Circuits
Sine to Square Wave
Voltage to Current
voltage to frequency
Period to Voltage
Video Wall circuits
TV Video Circuits
Motor Control Circuits
8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Human to Robotic Voice changer circuit
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 reliable circuit that will solve many problems in cases where a voice needs to be...
LF or HF field strength meter
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 and C2 is charged at the peak RF level. This dc level is amplified by an LM358. The gain is...
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 detector, allowing you to trace the wire to its source. Transistor Ql, along with piezoelectric...
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 more segments of its LED bar-graph display light, which aids in direction finding. The...
Door open alarm
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 position alarm. When the door is opened, an LED turns on and the piezo alarm sounds for...
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 photoresistive cell varies inversely as the light intensity; resistance is high when the illumination...
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 energy by adjusting the bias on the pick-up diode, Dl, with R2.
Based video surveillance system image sensor interface circuit
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
Wireless Keylogger circuit
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 is transmitted through the radio-link in real-time, rather than getting stored. The...
Simple Magnetic Contact Alarm Project
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 held at logic "1" by resistor R1. S1 switch is a normally open push-button switch which...
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 compact and consumes very little power. It is small enough to be hidden in anything you...
MICRO FM Bug
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 an input, output and earth lead. The mylar diaphragm has been permanently charged with a...
very stable BUG
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 of the most important features of this project is the use of standard components. This...
FM transmitter with two 2N3904
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 and the first transistor, this amplifies the sound from the microphone so that it can be...
Dual phone line auto recorder
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 in the Fig.1. The circuit stimulates when earphone from a telephone unit is raised,...
Infrared motion detector
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 to prevent activation of the load during daylight.
Video Camera switcher MAX454
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 sequencing through only the inputs that are connected to a camera. In the automatic mode, the...
FM Bug detector 80 - 150 MHz
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 will be a feedback whistle. The Bug Detector will not determine the output power of a...
Phone line FM transmitter
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 the active telephone lines, and thus avoids use of any external battery or other power...
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 .
Electronic Spy Bug Circuit
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 range of about 30 meters, over an ordinary FM radio. The circuit is basically a high gain ampli
Phone Spy Transmitter
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 its power directly from the active telephone lines, and thus avoids use of any external...
Spy FM Transmitter circuit
Remote Operated Spy Robot Circuit
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 meters. It overcomes the limited range of infrared remote controllers. This robot consists of
Spy Phone Bug Transmitter Circuit
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 power directly from the active telephone lines, and thus avoids use of any external ba
Spy Telephone Circuit
This FM spy telephone circuit is mounted serrial with the phone line. When is signal on the wires this transmitter will radiate airwaves thru the wires wic..
Spy RF Bug Detector Circuit
Here is a simple RF bug detector that will help you detect spy bugs and can operate up to 2 GHz. Below are some essential things required for this circuit:..
Surveillance Transmitter Detector
Surveillance Transmitter Detector
SPY 5000 two-way motorcycle alarm into a Honda 1998 CB250 Nighthawk
This Instructable describes the installation of a SPY5000 two way motorcycle alarm with a Honda 1998 CB250 Nighthawk motorcycle. This Alarm is rat..
1980 RCA TC-2811 First Generation CCD Surveillance Camera
RCA made some of the first commercially available CCD chips. A CCD (Charge Couple Device) is a silicon solid state imaging device that replaces the vidicon tubes of the past. CCD`s are made up a two dimensional array of photo detectors coupled to an array of shift registers. In operation, the imaging cy
Outdoor surveillance with condenser microphones
Condenser Microphones typically sound better than dynamic microphones. If you are unfamiliar with these two types of microphones you may want to read about them in this Wikipedia article. Electret condenser microphones have to little plates (capacitor), one of which vibrates in the presence of sound. The varying capacitance is turned into an elec
Surveillance Bug Circuits
Ultrasonic distance finder circuit
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 measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
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 find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
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 circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
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 circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
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, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
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 calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
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 supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
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. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity