Welcome!

UM66 is a pleasing music generator IC which works on a supply voltage of 3V. the required 3V supply is given through a zener regulator. its out put is taken from the pin no1 and is given to a push pull amplifier to drive the low impedance loud speaker. A class A amplifier before push pull amplifier can be used to decrees the noise and improve out put. UM66 is a 3 pin IC package just looks like a BC 547 transistor.... [read more]

This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone. By using the Expansion Modules, you can add as many zones as you require; some or all of which may be the inertia (shock) sensor type.... [read more]

Like the first two Hijack Alarms - if a door is opened while the ignition is switched on - the circuit will trip. And after a few minutes delay - when the thief is at a safe distance - the Siren will sound. But this time the engine does not go on to fail automatically. Instead - it will continue to run until the thief turns off the ignition. Then the engine will not re-start.... [read more]

Readers who do not care to modify the power supply of an old PC into a suitable halogen power source (see our April 2006 issue), may find the present design a welcome alternative. The circuit does not need any changes to the power supply. It allows the halogen lamps to be initially powered from the 5V rail of the supply via RE2, so that they are preheated. Subsequently, they are powered from the 12-V rail via RE1, while at the same time the 5-V rail is disconnected.... [read more]

This timer will provide a sequence of up to ten separate events. The length of each event is set independently. And the sequence will run a fixed number of times - or repeat continuosly. The individual events within the sequence - can be made to repeat and/or overlap. The accompanying Support Material includes a detailed description of how the Cmos 4017 works.... [read more]

The two circuits illustrate opening a relay contact a short time after the ignition or ligh switch is turned off. The capacitor is charged and the relay is closed when the voltage at the diode anode rises to +12 volts.... [read more]