Infrared Proximity Detector Alarm
This circuit can be built from readily available low-cost components, some of which may even be hiding in your junk-box! The indicated value of 22 for resistor...
Temporarily Silencing A Smoke Detector
It provides a means of temporarily silencing a battery-powered smoke detector after you`ve burnt the toast, scorched the baked beans or whatever! Unlike the ear...
darkness activated alarm
Most darkness activated alarms employ opamps and some logic ICs. Here, a less expensive approach is shown based on the eternal 555, this time in monostable mult...
park aid schematics
IC1 forms an oscillator driving the infra-red LED by means of 0. 8mSec. pulses at 120Hz frequency and about 300mA peak current. D1 & D2 are placed facing the ca...
monitor life extender
This circuit was designed to protect a computer monitor from overheating. It is recommended to attach this circuit to power users` monitors! Most computer monit...
general purpose alarm
The alarm may be used for a variety of applications, such as frost monitor, room temperature monitor, and so on. In the quiescent state, the circuit draws a cur...
cat and dog repellent
The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, which c...
simple home alarm system pcb
This Home Alarm System is simple, secure, fast and cheap. It`s only few components with maximum security with Rolling Code TX and Shock Sensor with variable sen...
police siren pcb
This circuit produces a sound similar to the police siren. It makes use of two 555 timer ICs used as astable multivibrators. The frequency is controlled by the ...
enhanced 4 digit alarm
Circuit Pressing a single key on the keypad - will energize the relay. Entering a four-digit code of your choice - will de-energize the relay. The circuit was d...
doorknob alarm pcb
Circuit Many companies offer simple alarm devices for personal use in bedrooms or hotel rooms. A metal chain attached to a box holding the electronics is placed...
4 in 1 burglar alarm pcb
I n this circuit, the alarm will be switched on under the following four different conditions: 1. When light falls on LDR1 (at the entry to the premises). 2. Wh...
laptop protector schematics
Protect your valuable laptop against theft using this miniature alarm generator. Fixed in-side the laptop case, it will sound a loud alarm when someone tries to...
car burglar alarm timer
Car Burglar Alarm timer alarm system circuit, model to economize. This circuit convenients for to set up in an automobile. usually switch at set up keep with au...
transistor based burglar alarm
This is a simple transistor-based burglar alarm circuit. Its features include automatic Exit and Entry delays - together with a timed Bell cut-off and Reset. It...
one time only burglar alarm
This alarm is designed to sound its Siren only once. That is - when the alarm is activated - the Siren will sound for a preset length of time. Then it will swit...
motorcycle alarms numbers
These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6...
garageshed alarm
This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays. It`s designed to be used with the usual types of norma...
electronic mouse trap
This circuit uses a conventional spring loaded mouse trap, available from hardware stores. However when a mouse is caught, the circuit triggers and transmits an...
safe and security system
This security system is very important for any kinds of home, office, factor. there has a circuit diagram its simple and easy to build. Any one can do it. It`s ...