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Three phase auto changer circuit – Circuit Schematic
Three phase auto changer circuit
This circuit is a modification of High & Low voltage cut-off with delay& alarm circuit appeared in Circuits today, which I have tried and found to be quite reli...
Sensor Circuits – Circuit Schematic
Sensor Circuits
Here is a simple mains power failure alarm/detector circuit that produces an alarm whenever the mains supply fails. Lot of such circuits are available, but the ...
Alarm Circuits – Circuit Schematic
Alarm Circuits
High Power Siren Circuit This article is all about a comparatively strong siren circuit useful for any purpose. A complementary transistor pair (BC 557 & 337) i...
Sensitive Intruder AlarmCircuit using 555 IC and 741 IC – Circuit Schematic
Sensitive Intruder AlarmCircuit using 555 IC and 741 IC
Here is the circuit diagram of an ultra sensitive intruder alarm. The shadow of an intruder passing few meters nearby the circuit is enough to trigger the alarm...
Electronic Combination Lock Circuit using IC LS 7220 – Circuit Schematic
Electronic Combination Lock Circuit 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...
Burglar Alarm Circuit with Diagram – Circuit Schematic
Burglar Alarm Circuit with Diagram
A simple burglar alarm circuit diagram and schematic. This can be used as anti theft alarm by attaching the burglar alarm circuit to window foil.....
Shock alarm circuit – Circuit Schematic
Shock alarm circuit
Here is a simple shock sensitive alarm circuit that has many many applications fro home to automobiles. The main application of this circuit is to use it as an ...
Ringing phone light flasher – Circuit Schematic
Ringing phone light flasher
When the telephone rings the line voltage rises to 72 volts. At this time the LED in the opto-coupler glows and the transistor conducts. Due to this the transis...
Rain Alarm Circuit-Science project with rain detector circuit-Working – Circuit Schematic
Rain Alarm Circuit-Science project with rain detector circuit-Working
The rain alarm circuit working is explained in detail. The rain alarm project is explained with circuit diagram.....
Police siren – Circuit Schematic
Police siren
The circuit given here produces an alarm similar to the police siren. When you press the push button switch S2 capacitor C1 will charge and this will make the t...
PIR Sensor Based Security System circuit diagramworkingapplications – Circuit Schematic
PIR Sensor Based Security System circuit diagramworkingapplications
PIR (Passive Infrared Radial) Sensor Based Security System, circuit diagram,working,applications.....
Parking sensor circuit – Circuit Schematic
Parking sensor circuit
This simple circuit can be used as an aid for sensing the distance between the rear bumper of the car and any obstacle behind the car. The distance can be under...
One transistor code lock – Circuit Schematic
One transistor code lock
This is of course the simplest electronic code lock circuit one can make. The circuit uses one transistor, a relay and few passive components. The simplicity do...
Infrared Motion Detector Circuit-IR motion sensor circuit with motion detector alarm – Circuit Schematic
Infrared Motion Detector Circuit-IR motion sensor circuit with motion detector alarm
Infrared (IR) Motion Detector Circuit with motion detector alarm and infrared sensor.The motion sensor circuit diagram and working is given in detail.....
High Power Siren Circuit – Circuit Schematic
High Power Siren Circuit
A siren circuit with diagram, which produces a strong,high power siren or alarm sound using complimentary transistor pairs BC 557 and BC 337,arranged as oscilla...
High-Low voltage cut-off with delay and alarm with circuit diagram – Circuit Schematic
High-Low voltage cut-off with delay and alarm with circuit diagram
The high and low voltage cut-off with delay and alarm circuit with circuit diagram is explained in this post.....
Fridge Door Alarm – Circuit Schematic
Fridge Door Alarm
Fridge Door Alarm circuit or a Refrigerator door open alarm using 555 Timer IC, which produces an audible alarm if the door left open for a preset time.....
Simple Fire alarm circuit using LDR – Circuit Schematic
Simple Fire alarm circuit using LDR
Here is a simple fire alarm circuit based on a Light Dependent Resistor (LDR) and lamp pair for sensing the fire. The alarm works by sensing the smoke produced ...
Electronic siren circuit – Circuit Schematic
Electronic siren circuit
This is a compact electronic siren circuit based on three transistors. This circuit is suitable for in corporating with other alarm or siren projects such as bu...
Door handle alarm – Circuit Schematic
Door handle alarm
The automatic door handle alarm circuit gives a audible alarm and glows a LED when somebody touches the handle of the door. The circuit is latching type and con...