G. Pradeep (9)

1-12-2002 | This little circuit may act as a vibration-activated burglar alarm. The sensor, which may be secured unobtrusively to a door or a window, is...

1-12-2002 | Here’s a 555-based project that can be used as mailbox alarm. By suitable mounting of the LED and the phototransistor, the circuit is able t...

1-07-2002 | This infrared alarm can be used to detect persons passing through doorways, corridors and small gates. The transmitter emits a beam of infra...

1-07-2000 | This is a short-range light barrier for use as an intruder alarm in doorposts, etc. The 555 in the transmitter (Figure 1) oscillates at abou...

1-12-1998 | The alarm circuit uses infra-red light beams to bridge distances between 3 m and 5 m (10 ft to 16 ft), but if the transmit diode is give...

1-12-1998 | The function of this circuit is to sound a buzzer, or, optionally, actuate a relay, when a certain moisture level is detected between a...

1-07-1998 | The circuit presented here illustrates the fact that in spite of all kinds of new component and technology, it is still possible to desi...

1-12-1997 | Here is a very easy and inexpensive way of building a crystal oscillator from a Single lC. Only two of the inverters contained in the IC...

1-12-1997 | This inexpensive VHF preamplifier uses the BF324 1092 style pnp transistor in a grounded-base configuration. The circuit may be used as a...