Circuit Alarm

This be simple circuit alarm diagram for extremely the electronics everyone.
Try build keep be usable example , alarm system of the usability
be home security alarm circuit, car alarm circuit, fire alarm circuit,
burglar alarm circuit etc. By compose many circuits as follows �

Proximity Detector Using CS209
Rain Alarm using NE555
Low Cost Fire Alarm Circuit Using Transistor
Fire Alarm Using Thermistor
Chamberlain Wireless Alert System
Water Softener Circuit using NE555
8-Zone Water Sensor Alert Kit
Water Sensor Alarm
Wireless Portable Video Security System LCD - Outdoor Camera
Skylink WT-433 Window-Door Sensor
Personal Alarm using IC 74HC04
Lamp flashing alarm automatic
Car Alarm Simulator
Car Burglar Alarm system with radio wave signal
Car Burglar Alarm timer delay using NE556
Simple Metronome using transistor
Warbling Alarm Circuit with tone Generator
Wireless Home Security System Calls Your Cell Phone
Home and Vehicle 2-Zone Alarm Pager System
Emergency power siren 6 watt
Water Sensor Alarm Kit
Car Alarm Simulator by LM324
Water Sensor Alarm using LM380
Two Tone Alarm generator using LM3900
Electronic Watch Dog Kit
Mini Emergency Light by 9013 transistor
Headlight Alarm
Powerful Siren by BC337
One-IC two-tones Siren with IC 4093
Electronic Siren by IC Digital
Single Zone Digital CMOS Alarm
Miniature Loop Alarm
Red Alert Startrek Alarm by IC 555
American Police Car Siren by IC 555
British Police Car Siren by IC 555
Two HiJack Alarms by 4001
Water Alarm with LM380
Two Tone Alarm with IC LM3900
Mosfet 6 Watt Siren
Travel Touch Alarm
Assortment of Siren Circuits

Two HiJack Alarms

Circuit :Ron J
Email Ron:

Description:
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 - the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the alarm will sound and the engine will fail.

Notes:
You're going to trip this alarm unintentionally. When you do - the LED will light and the Buzzer will give a short beep. The length of the beep is determined by C3. Its purpose is to alert you to the need to push the reset button. When you push the button - the LED will switch-off. Its purpose is to reassure you that the alarm has in fact reset.

If the reset button is not pressed then - about 3 minutes later - both the Siren and the Buzzer will sound continuously. The length of the delay is set by R7 & C4. For extra effect - fit a second siren inside the vehicle. With enough noise going on - you may feel that it's unnecessary to fit the engine cut-out. In which case - you can leave out D8, D9, R11, R12, R13, C6, Q3, Q4 & Ry2.

Even if you missed the early warning provided by the Buzzer - there is still time to reset the alarm before Ry2 de-energizes - and the engine fails. This additional delay - currently about 1 minute - is set by C6 and R13.

To reset the circuit you must - EITHER turn off the ignition - OR close all of the doors - before you press the reset button. While BOTH the ignition is on - AND a door remains open - the circuit will NOT reset.

The reset button carries virtually no current - so any small normally-open switch will do. Eric Vandel from Canada suggests using a reed-switch hidden behind (say) the dash - and operated by a magnet. I think this is an excellent idea. As Eric said in his email: - "... that should keep any thief guessing for a while."

The Flow Chart is another of Eric's suggestions. It will help you to visualize how the alarm is operated. It also explains the sequence of events that lead to siren activation - and subsequent engine failure.

Source:: http://www.zen22142.zen.co.uk/Circuits/Alarm/hijack.htm

Door Buzzer by NE555 + LM386

Circuit Door Buzzer by NE555 + LM386

Two Tone Alarm with IC LM3900

Circuit Two Tone Alarm with IC LM3900

Opto-Thermo Alarm with IC 741 & 4001

Circuit Opto-Thermo Alarm with IC 741 & 4001

Car Battery Alarm

circuit Car Battery Alarm

Mosfet 6 Watt Siren

circuit Mosfet 6 Watt Siren

Light-sensitive Alarm

The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.

- The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
- The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.

Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.

source : http://www.free-electronic-circuits.com

Assortment of Siren Circuits

This month I am making 3 different types of siren circuits based on the 555 timer. The first circuit simulates the siren of a British police car. It uses two 555 timers in the circuit. The 555 on the right is wired as an alarm tone generator and the second 555 timer on the left is a 1 Hz astable multivibrater. The output of the left timer is to frequency modulate the right timer. This causes the right timers frequency to alternate between 440Hz and 550Hz at a 1 Hz cyclic rate. The transistor is used to help strengthen the signal to the speaker.

The second circuit simulates the siren of an American police car. It uses two 555 timers in the circuit. The 555 on the right is wired as an alarm tone generator and the second 555 timer on the left is wired as a low frequency astable timer which generates a ramp waveform of about 6 seconds that is buffered by the transistor and again used to frequency modulate the tone generator. The transistor is used to help strengthen the signal to the speaker.

The third circuit simulates the "Red Alert" siren from the TV show Star Trek. It uses two 555 timers in the circuit. The 555 on the right is wired as an alarm tone generator and the second 555 timer on the left is wired as a 1.5 second non-symmetrical astable that generates a fast rising but slow falling saw tooth waveform. This waveform is buffered by the transistor and used to frequency modulate the tone generator and making its frequency rise slowly during the falling parts of the saw tooth but collapse rapidly during the rising part of the saw tooth. The output starts as a low frequency, rises for 1.15 seconds to a high tone, ceases for .35 seconds and then repeats the cycle.

From : http://home.maine.rr.com/randylinscott/feb21.htm

Travel Touch Alarm

The Travel Touch Alarm can be used to provide a audible alarm when someone touches the door knob or handle of your hotel room. The door knob or handle must be made of metal for the circuit to work. The main chip in the circuit is a 555 timer which will be triggered if a hand comes close to or touches the door knob. The circuit attaches to the door knob at the end of the 1 meg ohm resistor. Once the timer is triggered the LED will light and the UJT will output a tone to the speaker. The timer will time out in 5 seconds. The sensitivity of the trigger can be changed by changing the 1 meg ohm resistor to another value. The 5 second time out can be adjusted by changing the value of the resistor connected between pin 8 and pin 7. The output tone can be changed by changing the RC values on the base of the UJT.

From : http://home.maine.rr.com/randylinscott/jul20.htm

Sun - Up Alarm

The Sun - Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine) The sun shining on this device will provide a high to one of the NAND gates. This will cause another NAND gate to oscillate which will drive another gate to output a 100hz tone. The transistor provides drive for the speaker.

From : http://home.maine.rr.com/randylinscott/jun20.htm

Auto Burglar Alarm

This alarm circuit is based on two 555 timers. The alarm will sound your car horn if anyone opens the car door while the circuit is armed. The timers will allow you to leave the car without sounding the horn. To turn the circuit on S1 must be closed. To set the alarm, open S2 ( it is normally closed ) this will give you about 5 seconds to get out and close the door. The exit delay time is set by R1 and C1. If anyone opens the doors for more then two seconds the horn will sound until power is removed from the circuit. The 2 second time is set by R2 and C2. If you open the door, you must deactivate the alarm by closing S2. This very basic circuit could be used for a home also.

From : http://home.maine.rr.com/randylinscott/jan20.htm