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Three Flashing LED Doorbells For The Hearing Impaired – Circuit Schematic
Three Flashing LED Doorbells For The Hearing Impaired
When the push switch is operated - the buzzer will sound and the LEDs will begin to flash. For the hearing members of the household - the buzzer acts as a regul...
Talking Nixie Alarm Clock – Circuit Schematic
Talking Nixie Alarm Clock
The B8422 Nixie tubes were destined to end up in an alarm clock on my bedside cupboard. My house is slowly filling up with homemade clocks, only our bedroom has...
door loock circuit – Circuit Schematic
door loock circuit
This is a great contribution to the ongoing study of the lock control module, including instructions and photos of how to upgrade the module to reduce its stand...
Laser Alarm Schematic – Circuit Schematic
Laser Alarm Schematic
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Remote Alarm For Smoke Detector – Circuit Schematic
Remote Alarm For Smoke Detector
This alarm circuit was designed to monitor a mains-powered smoke detector located in a shed (which is used to house dog kennels). It provides complete isolation...
Miniature Loop Alarm – Circuit Schematic
Miniature Loop Alarm
A few months ago, I decided to build a compact, yet effective alarm. My demands were:- simple construction, reliable operation, very small power consumption, an...
Car Alarm and Immobilizer – Circuit Schematic
Car Alarm and Immobilizer
This circuit features exit and entry delays, an instant alarm zone, an intermittent siren output and automatic reset. By adding external relays you can immobili...
Electronic Combination Lock using IC LS 7220 – Circuit Schematic
Electronic Combination Lock using IC LS 7220
This is the circuit diagram of a simple electronic combination lock using IC LS 7220. This circuit can be used to activate a relay for controlling (on & off) an...
Transmitter Detector for FM Bug Surveillance – Circuit Schematic
Transmitter Detector for FM Bug Surveillance
The circuit was constructed using a few components that is powered by a 9 V battery for sensing the presence of bugs transmitting within the frequency modulatio...
Hijack Alarm – Circuit Schematic
Hijack Alarm
The first circuit was designed for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on - th...
Wailing Alarm Siren – Circuit Schematic
Wailing Alarm Siren
This alarm siren circuit produce warbling sound, you can use it in your toys or in security alarm. The circuit use two 555 IC oscillator. In this alarm siren ci...
Motorcycle Alarm – Circuit Schematic
Motorcycle Alarm
This alarm is easily adapted for a 6-volt system. So it will protect your "Classic Bike". And - because the standby current is zero - it won`t drain your batter...
Cut Phone Line Detectors – Circuit Schematic
Cut Phone Line Detectors
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Telephone line monitors – Circuit Schematic
Telephone line monitors
If you feel that somebody is tampering with your telephone line you might find this little circuit useful. It detects if there is another telephone connected to...
Fuse Monitor / Alarms – Circuit Schematic
Fuse Monitor / Alarms
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Doorbell for the Deafs – Circuit Schematic
Doorbell for the Deafs
This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will l...
Electronic Lockers – Circuit Schematic
Electronic Lockers
This circuit is an Electronic Locker. It is controlled by a switches combination (by a code). There is a switch matrix on the door of the locker. This one is a ...
iButton electronic locks – Circuit Schematic
iButton electronic locks
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Door Alarms – Circuit Schematic
Door Alarms
This circuit emits a beep and/or illuminates a LED when someone touches the door-handle from outside. The alarm will sound until the circuit will be switched-of...
Field-strength meters – Circuit Schematic
Field-strength meters
This circuit, enclosed in a small plastic box, can be placed into a bag or handbag. A small magnet is placed close to the reed switch and connected to the hand ...