Alarm Circuits
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This is an Infrared based Broken beam alarm to protect doors and entry passages. It gives a loud alarm when somebody crosses the Invisible Infrared barrier.... -
This small water sensor alarm circuit makes a loud warning sound when a humidity sensor detects a quantity of water. This circuit assembly is an application of low power comparator LM1801 made by National Semiconductor. The reference voltage for the.... -
This simple alarm timer circuit is made with 4060 which has an integrated oscillator with a good stability with a relatively wide frequency range. In the c.... -
This fridge door alarm is using a 3V battery supply should be placed (in a small box) in the fridge near the lamp or close to the opening. With the door cl.... -
This Simple circuit can be used to Guard your bike from theft. It gives a loud alarm tone if somebody tries to start the bike. The alarm disables only when the hide switch S2 is opened. The circuit has little component count and can be easily fixed in the.... -
This temperature monitor alarm circuit continuosly monitors the room temperature and beeps when the temperature drops below 20 degrees centigrade. This capability to constantly monitor the room temperature can help lower your air-conditioning costs by.... -
Ultra simple circuit of the tilt sensor alarm presented here can be fabricated using readily available inexpensive components. The circuit is a true transistor based design. Home made Tilt sensor for this circuit is an ordinary little glass/plastic bottle.... -
This little PC Watcher circuit will help you to prevent unauthorised access to your personal computer. After construction on a small piece of veroborad, en.... -
The simple pressure sensor alarm is built around a couple of readily available cheap components. Working of this circuit is straight forward and self-explanatory. When the circuit is powered by a 9V compact battery, the active piezo-sounder at the output of.... -
Circuit of a loop sensor based simple security alarm is described here. The sensor loop is nothing but a short length of thin enamelled copper wire, which.... -
Ever accidentally left your front door ajar and had a pet escape Here is a smart solution to this problem. The circuit is fairly simple but a great example of using a tiny circuit to get the job done. All you need is a CD4011 IC plus a handful of components..... -
This circuit uses invisible infrared light to detect the movement of people through the door. A short beep will be generated when the infrared beam breaks .. -
A very interesting remote controlled alarm circuit using TSOP1736. Routing of an electric cable to attach a calling bell switch near the bed of an old age/patient is not a good idea. Here is an ultra simple battery operated remote controlled alarm to help.... -
The high temperature alarm will beep and LED blinks when the temperature of the device increases abnormally. This simple over heat alarm is to monitor heat.... -
Here is a simple power resumption alarm circuit that can be fixed inside the switch box itself. It gives beeps when the power resumes after a power failure.... -
A simple light fence security beeper is presented here. This circuit can be used as a door alarm, gate alarm, pathway alarm, etc. Any 12 Volt dc power supply can power the whole circuit. Working of this circuit is straight forward. In standby mode photo.... -
Here is an ultra simple automatic light switch circuit for bedrooms. After construction, connect the input terminals of this circuit in parallel to the int.... -
This musical light alarm circuit is very simple, uses only 7 components, a LDR and a 3. 6 V battery or 3 x 1. 2 volts rechargeable batteries. The well-known UM66 is used as the sound generator and will give a pleasent wake up alarm. As you probably know the.... -
The circuit is a precision integrated temperature sensor type LM35 (IC1), which provides an accurately linear and directly proportional output in mV, over the zero to +155 degrees C temperature range. This can be used as part of fire smoke detectors but do.... -
I hate to suggest the specific application `bicycle` because it may be use to protect many items from theft. This anti-theft alarm project is built around.... -
This infrared alarm barrier can be used to detect persons passing through doorways, corridors and small gates. The transmitter emits a beam of infrared light which is invisible to the human eye. The buzzer at the output of the receiver is activated when the.... -
The original smoke alarm circuit has some problems and has left some hobbyists and students disappointed. Rather than to attempt to solve its many problems, I have created an update that uses the venerable LM741 op amp. It is simpler, more conventional,.... -
Shadow sensors are widely used to detect the movement of a person in a confined area. Many circuits published earlier have a serious drawback that only one.... -
Here is the circuit of an Arduino-based Panic Alarm! The wiring is very simple so that even a novice can construct this interesting circuit without any difficulty. Arduino is a family of microcontrollers (tiny computers) and a software creation environment.... -
Crime in general is still on the rise, and having a security alarm installed is no longer a perquisite of the wealthy! Here is a simple and compact securit.... -
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.... -
Digital IC, Door Knob alarm Here is circuit if you want an alarm to be sounded when somebody touches some thing. If any body touches say, the door handle, buzzer inside rings. But.... -
IC 555, Light Alarm (Sun Up Alarm) , This circuit designed to sound a loud alarm at the break of the dawn especially for those wh cannot wake up even with an alarm clock. Circuit can be modifi.... -
Locker Guard Circuit Diagram. This tiny circuit can protect your Locker or Almirah from a burglary. If the locker opens in the armed state, the circuit generates a loud police siren to thwart the attempt of burglary .. -
Personal Alarm Circuit Diagram. If you feel threatened or need an urgent support in a crowd, use this alarm to catch the attention of others .. -
Simple Burglar Alarm / Door Alarm Circuit Diagram. You can use this Simple project to protect the door or Window. It gives a loud beep and switch on the room light when an intruder attempts to breaks the door lock .. -
A car alarm in its simplest form, needs to be nothing but one or more sensors connected to some sort of siren. The very simplest alarm would have a switch on the driver`s door, and it would be wired so that if someone opened the door the siren would start....
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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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