Auto-Arming Car Alarm circuit
The car alarm here is a simple circuit with basic characteristics that cover all entrances at the car that has switches (doors etc).With one switch (arm-switch)...
Infrared light trap circuit
This infrared light valve has more parts, so it works better and more reliable for alarms. The circuit responds less ambient light. The light valve consists of ...
Wireless Bug detector
This fairly simple circuit makes it possible to place such a wall as a conduit to locate. It is a conduit for power, no water or gas-seeker. The only requiremen...
Extra security for radio controlled alarms
This is a small circuit that provides extra security for radio controlled models. When the signal from the transmitter fails, grab the circuit and set the servo...
Auto-Phone dialer for alarm security system
The circuit consists of a small PIC microcontroller, assembly program,
and a few other parts to detect a switch closure from an open door, window,
or manual p...
Keypad Combination Lock circuit
This simple circuit is the electronic version of the combination lock. Using the special purpose LS7220 digital lock IC, the circuit allows a 4 digit combinatio...
Car Alarm Arming Beep Canceller
It's a great convenience that most modern cars come with a built in alarm, however it is nothing but noise pollution that the horn sounds when the alarm is arme...
Phone line audio muting circuit
Very often when enjoying music or watching TV at high audio level, we may not be able to hear a telephone ring and thus miss an important incoming phone call. ...
telephone line loger
Here is a telephone line vigilant circuit to guard against mis- use of your telephone lines. It monitors telephone lines round the clock and provides visual as...
Sound activated switch circuit
An infra-red or wireless remote control has the disadvantage that the small, handy, remote transmitter is often misplaced. The sound operated switch has the adv...
High-Low Voltage Cutout with delay
Voltage variations and power cuts adversely affect various equip- ment such as TVs, VCRs, music systems and refrigerators. This simple circuit will protect the ...
Programmable Code Lock circuit
A programmable code lock can be used for numerous applications in which access to an article/gadget is to be restricted to a limited number of persons. Here is ...
Sound Controlled Switch
Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorde...
Water level alarm
This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full.
The circuit uses the widely ava...
Rain detector alarm
This circuit gives out an alarm when its sensor is wetted by water.
A 555 astable multivibrator is used here which gives a tone of about 1kHz upon detecting wa...
Wire loop theft alarm
This circuit utilising a 555 timer IC can be used as an alarm system to prevent the theft of your luggage, burglars breaking into your house etc. The alarms go...
power supply alarm circuit
Most of the power supply failure indicator circuits need a separate power supply for themselves. But the alarm circuit presented here needs no additional supply...
Daylight alarm with 555
The circuit presented here wakes you up with a loud alarm at the break of the daylight. Once again the 555 timer is used here. It is working as an astable multi...
Fire activated alarm
This circuit warns the user against fire accidents. It relies on the smoke that is produced in the event of a fire. When this smoke passes between a bulb and an...
Car wireless alarm
This FM radio-controlled anti- theft alarm can be used with any vehicle having 6- to 12-volt DC supply system. The mini VHF, FM transmitter is fitted in the ve...