Archive for the ‘Security’ Category
Loud 10-W Car Alarm Siren
By generating square-wave output that sweeps down and up in frequency, this circuit can produce force field of high-intensity sound inside car. This circuit can make a car thieve panics and decide to run before anyone catch his action. D1, C1 and R1 produce triangle waveform by shaping a square wave output of IC1. If …[Read More]
One Direction Motion Sensor
This is a one direction motion sensor circuit. This motion sensor circuit is used to detects an object passing in one direction, ignoring an object that going to opposite way. This circuit uses two sensors to identify the movement only in one direction. The basic principle of this circuit is simple, where one sensor is …[Read More]
The voltage boosting in this circuit enable its operation to be powered by 2.5 V rechargeable battery (two cells 1.2V rechargeable batteries), supplying 400 mA current at 26 V which is needed by the gas arc tube for portable ultraviolet lamp. This inverter circuit has a good efficiency as well, about 80%. Ultraviolet (UV) light …[Read More]
555-IC Timed Beeper/Alarm
This is a simple circuit of beeper using 555 timer. This circuit can be employed to energize lights, horn, or other signaling device at any desired interval when the mercury switch is triggered. Since the current handling capability of mercury switch is not so high, an SCR is used to handle current drawn by the …[Read More]
Simple Code Lock
This is Simple Code Lock circuit. This circuit will turn on a relay when the 8-way DIP switches receives the correct code. Here is the schematic diagram of the circuit: There are two different types of DIP, they are piano-key DIP sw and 8-way DIP sw. This circuit will not draw the current if …
Siren Driver Circuit
This is a driver circuit for siren. This circuit usually used for car alarms. To build this circuit, we use VD-MOS FETs. This circuit receives 12 v supply from battery. A microprocessor sends complementary pulse waveforms to the driver circuit as inputs. Here is the circuit : This circuit uses two PHC21025 which each …
Provide Remote Alarm for Smoke Detector
Ionization-based smoke detectors are efficient and cheap, so they are often installed in the house, other outbuildings, and the garage. The Locations of the device is far from house, so we need to transmit the alarm signals back into central home-security system or the house. This is a simple circuit that sense a supply current …[Read More]
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