Alarm Circuits
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Opening car`s door is very simple activity, and off course it`s just a daily activity which require no special skill. Almost nothing can go wrong, but.... -
At high speed, visually checking your speedometer to keep under maximum speed can be dangerous. It will be much safer if we put an audio alarm system to give a.... -
[The following circuit is adapted from battery monitors and testers published in The Smith-Kettlewell Technical File (SKTF). The first appearance of this system was "The Smith-Kettlewell Battery Tester, Where Silence is Golden", SKTF, Volume 11, No. 1,.... -
A low cost high performance programmable home security system using few LDR`s as an input sensors. When above sensor(s) get triggered system may dial the user specified phone number (using build-in DTMF generator) and activate the high power audio alarm and.... -
This is a simple alarm circuit which produces a musical tone when water or some conducting liquid comes in contact with the two sensor wires provided. The circuit is based on four transistors and one melody generator IC (M 3482). When water comes in contact.... -
The emergency driver unit consists of a battery charger and electronic circuitry in one compact case. The batteries. Emergency lighting battery protection from over current and heat. Liquid. Crystal Display. (LCD) screen protection from short circuit and.... -
A Cmos 4060 Burglar Alarm Circuit This is a single zone alarm - with automatic exit, entry and siren cut-off timers. It will accommodate all the usual types of normally-closed input devices - such as magnetic-reed contacts - foi.... -
A Cmos Based Motorcycle Alarm Circuit This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automaticall.... -
A Dozen Small Cmos Alarm Circuits Circuit Description This is a selection of small self-contained alarm circuits. The main features of each alarm are described on the circuit diagram itself. They all have a very low standby current. So they This is a.... -
A Simple Transistor Based Motorcycle Alarm Circuit This is a simple - easy to build - transistor based motorcycle alarm. It`s designed to work at 12-volts. But - if you change the relay for one with a 6-volt coil - it`ll protect.... -
This is a car alarm simulator which using the LED as a simulation output. This simple circuit can tell you whether your car is running or not by detecting the voltage difference when the car is on and off. This occurs because when your car This is a car.... -
This is door knob touch alarm for your home security purpose. The alarm will be activated when someone touch the metal door knod. This circuit wont work on full metal door. Download the schematic drawing This is door knob touch alarm for your home security.... -
This is the fire alarm circuit which use LDR to sense the smoke from the fire, so it can be used to detect any dark smoke. With the onset of summer season, possibilities of fire accidents go up. These fire accidents could be prevented if ti.... -
Here the simple schematic of multitone siren alarm circuit. This multitone siren is effective for reverse horns, burlgar alarms, and many others. It generates five various audio tones and is much more earcatching than a single-tone siren. T.... -
This is the special circuit design of power supply failure alarm. The vast majority of the power supply failure alarm / indicator circuits require a independent power supply for themselves. However the alarm circuit introduced right here re.... -
Vehicle Anti-Hijack Alarm No3 this circuit was designed primarily 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.... -
Here the wailing alarm circuit diagram: Component parts List: R1,R5 4.7KR2 47KR3 10KR4 100KRx *see text C1,C4 100uF/25V, electrolyticC2,C3 0.01uF (10nF),.... -
This circuit is a wireless car alarm system that is built using two circuit modules, namely modules of transmitter and receiver modules. This circuit works on FM radio waves. Car alarms can be used on vehicles that have a 6-12VDC power supp This circuit is a.... -
This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC`s and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system.... -
This alarm system has 6 independent zones, 1 timed entry/exit zone, a 7 segment LED display and a test or walkthrough facility. Suitable for a small office or home environment, it can also be adapted to use a combination lock or keypad to set and reset the.... -
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-volt coils - they`ll protect your "Classic Bike". Both alarms are very small. The completed.... -
This is a single zone alarm - with independently adjustable Exit, Entry and Siren Cut-Off timers. It will accommodate the usual types of normally-closed input devices - such as magnetic-reed contacts, foil tape and PIRs. If you wish - you can use a mains.... -
This section contains intruder alarms for your home, car and motorcycle, power failure and water level alarms and even a snore detector. All circuits are listed alphabetically on the Circuit Index page and in date order on the update page. All contributors.... -
This is a simple SCR based burglar alarm circuit. Its features include automatic Exit and Entry delays - together with a timed Bell cut-off and Reset. It`s designed to be used with the usual types of normally-closed input devices such as - magnetic-reed.... -
Although this Power Supply was designed for the Modular Burglar Alarm - it has other applications. It provides an output of 12-volts - at a current of up to 1-amp. In the event of a mains failure - the back-up battery takes over immediately. And when mains.... -
This circuit features automatic exit and entry delays - an optional instant alarm zone - an optional intermittent siren output - and an automatic reset. By adding external relays you can immobilize the vehicle and flash the lights. For automatic operation -.... -
The Cmos 4001 has four - independent - two-input NOR gates. The four gates are divided into two pairs. Gates 1 & 2 are wired together to form a type of latching circuit. When the alarm is triggered - they will latch - and sound the buzzer. Gates 3 & 4 are....
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This is a single zone alarm - with automatic exit, entry and siren cut-off timers. It will accommodate all the usual types of normally-closed input devices - such as magnetic-reed contacts - foil tape - PIRs etc. But it`s easy to add a normally-open trigger..... -
This is a simple - easy to build - multi-purpose alarm. Build it yourself using stripboard or veroboard and a few cheap off-the-shelf components. Fit it to a door, window, shed, garage, cupboard etc. It`ll alert you to intruders. Fit it to a shop-door - and.... -
Before fitting this or any other engine cut-out to your vehicle - carefully consider both the safety implications of its possible failure - and the legal consequences of installing a device that could cause an accident. If you decide to proceed - you will.... -
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 designed to control the Modular Burglar Alarm System - but it will have other applications. If you require.... -
This circuit is designed to be used with the Universal Keypad Operated Switch. A few genuine mistakes - made during code entry - will not activate the device. But repeated attempts to find the correct code by trial and error - will cause the keypad to....
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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