Alarm

Light Alarm

This is a simple Photo-sensing circuit. When light hits the photo-transistor, triggers the 4011 that drives a loudspeaker. Easy to make and can be very usefull too...

Car alarm circuit using 555 timer

Car alarm circuit using 555 timer

555 timer produces a guaranteed delay, allowing the driver to deactivate the alarm and the elimination of a control switch vulnerable outside...

House Alarm Loop Circuit

House Alarm Loop Circuit

This circuit offers open and closed loop contacts (switches 1,2,3) that triggers the alarm ON and stays ON for 5 -10 minutes. The trigering delay (entrance/exit) is 27 seconds. This simple alarm circuit Has also a cancel button for reseting the circuit to stand-by mode again......

Car Alarm Security Circuit

Car Alarm Security Circuit

This car alarm circuit offers 18 seconds delay for the entrance and the exit. It sound continually for 6 minutes and automaticaly turns horn off and gets ready for the next trigering.....

Simple House Alarm circuit

Simple House Alarm circuit

This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to few passive parts...

Clever Car alarm circuit

Clever Car alarm circuit

When this car alarm circuit is activated it stays activated for 80 seconds. It has 15 seconds delay for the driver to enter and deactivate. and All timmings can be altered easilly.....

Auto-Arming Car Alarm circuit

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) the circuit waits for the sensor-switches to open and to activate it. So the horn with 1 sec pulses will sound imediatelly seconds so the driver can enter in car and disactivate the arming switch. ..

Infrared light trap circuit

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 a transmitter and a receiver. The transmitter consists of a NE 555 which provides pulses to the infrared LED (D1) are fed. The frequency of the pulses is set to P1. On the receiver side we see the photo transistor T1 receives the pulses from D1. The pulses through C4 to the positive input of op amp IC2 led. Between the output of IC2 and the minus input is an RC network that ensures the lowest at about 7.2 kHz amplitude issues. ..

Extra security for radio controlled alarms

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 connected to a preset position. The circuit is built around a CMOS IC, the 4093 with 4 Schmitt trigger NAND gates. IC1b and IC1c together a astabiele multivibrator, which generates pulses for the servo. When a transmitter signal does not and this is the input signal is available at the output...

LED flasher with two transistors

LED flasher with two transistors

This circuit will flash a bright LED 5000mcd as an intention getting device or fake car alarm...

Auto-Phone dialer for alarm security system

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 push button and then dial the cell phone number, and transmit a steady tone to indicate the source of the call. The circuit uses the pulse dialing system to interrupt the line connection a number of times to indicate each digit. Pulse dialing (the oldest form of dialing) works by actually disconnecting or "hanging up" the phone line a number of times to indicate each digit. For example, the digit "5" would be dialed by disconnecting and reconnecting the line 5 times in short intervals of about 100mS. ..

Water level alarm

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 available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs. When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch low hence opening the switch and LEDs are OFF. As the water starts filling up, first the wire in the tank connected to S1 and the + supply are shorted by water. This closes the switch S1 and turns the LED1 ON...

Wire loop theft alarm

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 goes ON when a thin wire, usually as thin as a hair is broken. The circuit is straightforward. It uses a 555 IC wired as an astable multivibrator to produce a tone of frequency of about 1kHz which gives out a shrill noise to scare away the burglar. The wire used to set off the alarm can be made of a thin copper wire like SWG 36 or higher. You can even use single strands of copper form a power cable. ..

power supply alarm circuit

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 source. It employs an electrolytic capacitor to store adequate charge, to feed power to the alarm circuit which sounds an alarm for a reasonable duration when the supply fails. This circuit can be used as an alarm for power supplies in the range of 5V to 15V. ..

infrared beam proximity detector

infrared beam proximity detector

his circuit can be used as an Infrared beam barrier as well as a proximity detector. The circuit uses the very popular Sharp IR module (Vishay module can also be used). The pin nos. shown in the circuit are for the Sharp & VIshay modules. For other modules please refer to their respective datasheets. The receiver consists of a 555 timer IC working as an oscillator at about 38Khz (also works from 36kHz to 40kHz) which has to be adjusted using the 10K preset. The duty cycle of the IR beam is about 10%. This allows us to pass more current through the LEDS thus achieving a longer range. ..

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