Surveillance

This beeping bug can be attached to anything from a glider to a pot-plant and you can track it with an FM radio. The circuit consists of two building blocks - both are oscillators. The first operates at a very low rate (low frequency - about 2Hz) and the other operates at approx 90MHz. The first is a square-wave oscillator with a very short ON time, while the other is a sine-wave. The only thing they have in common is a feedback component, to create and maintain oscillation. In all other respects they are different...

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 static charge and this is one of the secrets of the operation of the microphone...

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 suspect will be lost or stolen. By using a mercury switch or "grasshopper" the bug can be "primed" for the time when it is moved and you can track it with an FM radio...

This project is a standalone simple home security monitoring project that will trigger a buzzer when the magnetic contact is opened...

Build Your Own Door Bell Chime using 555 timer integrated circuit, a speaker, 5 resistors, 4 electrolytic capacitors, 1 ceramic capacitor, 3 diodes, 1 pushbutton switch and 9 V battery as power supply...

Construct your own 9 V Siren based on LM358 operational amplifer(OP AMP). This powerful siren can be used to scare away unwanted visitors...

This project is a power supply monitoring device that will trigger a buzzer when the mains supply cuts off. At the same time, the light emitting diode will turn ON...

Construct a 6-15V Alarm by using LM/NE 556 dual timers. It will generate a noise level of 90db-110dB range...

Construct your own two station Intercom Project. It uses LM386 amplifier. Each intercom station has its own battery, speaker, microphone and amplifer circuit...

Schematic and parts list needed to construct a simple Light Alarm. Use this to protect your medicine cabinet, cash drawer or any cabinet...

Construct your own Electronic Lock by using two dual D flip-flop 4013. Four secret combination of numbers are used to OPEN this combination lock...