Alarm Circuits
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This article helps you to make a Light Sensitive Morning Alarm circuit. The morning light is sensed by an LDR (Light Dependent Resistor) or Photoresistor and it triggers the alarming section. The circuit generates a melodious tone when light falls on it..... -
This is a project that I undertook during June 1996 as my final year electronics project. The entire circuit was built using individual components including logic gate ICs and and keyboard decoder IC. Since them electronics has moved on and if this was.... -
The alarm detector circuit is different from Ultrasonic Alarm (1). In Ultrasonic Alarm (1), an alarm output is presented when there is a reflected wave from the object in the setup time. At the circuit this time, an alarm is output when no reflected wave.... -
U1 is the 3817 integrated circuit. It has the ability to drive the display directly, and it can display 12h or 24h, schedule alarm sounds, timely and automatically turn on the radio. Display is FND500 light-emitting diode, the input frequency is 50H or 60Hz..... -
As the figure 15-24 shows, the controller circuit is composed of the switch type Hall integrated circuit DN838 and the astable multivibrator (composed of the 555), this circuit can be used in wide range of applications such as the automatic door opening,.... -
The locker alarm circuit or cashbox watcher can be used to protect a cashbox/locker from unauthorised access. This tried and tested design forms a fool-proof,remotely operated alarm/electromagnetic relay driver that receives its control signal from a.... -
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.... -
Human infrared thermal release alarm can receive the heat releasing infrared ray issued by the body during the day or night, then it willgive the sound and light alarm. It is ideal for electronic guard. Working principle: The circuit uses imported IC,.... -
Infrared burglar alarm circuit schematic is shown in Figure 1. Infrared transmitter is a multivibrator with oscillation frequency being 40kHz, and it is composed of IC2 ( NE555 ), R1, R2 and C3. VLS is the infrared emission probe which can be used to radiate.... -
In the event of combustible gas, the conductance of TGS308 gas sensor increases, and the voltage is removed through the potentiometer RP1 slide point, and its value is increased from normal 3V rms to 20V. This elevated voltage is added to transistor VT1.... -
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.... -
When the switch is on, the seismic alarm isin detection condition. When there is no earthquake, IC1`s pin 3 outputs low level and VT is disconnected. The alarm circuit does not work. When there is an earthquake, the magnet will move vertically. When it is.... -
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.... -
Integrated circuit input side has a oscillating circuit,it`s oscillation frequency depends on external components L1, C1 and sensor`s equivalent capacitance, the latter size increases with liquid immersion. Oscillating signal add on the threshold switch.... -
The Motion Sensor Switch circuit is a motion sensor controlled automatic water sprinkler but you can easily add an alarm/light function too. Before beginning the construction contact your nearest electronics component vendor and procure a readymade box-type.... -
The principle of the circuit The motorcycle anti-thief alarm circuit is composed of the detection alarm circuit, the charging circuit and the anti-theft control circuit, this circuit is as shown in figure 7-94. The detection alarm circuit is composed of the.... -
The principle of the circuit The motorcycle anti-thief alarm circuit is composed of the anti-theft detection circuit, the control circuit, the sound generator, the audio oscillator and the power amplifier output circuit, the circuit is as shown in figure.... -
Work of the circuit The circuit consists of low-frequency oscillator, the electronic switch circuit, control circuit, photoelectric display circuit and music alarm circuit. (It is showed in picture 7-113.) Low-frequency oscillator consists of IC lCl (Dl-D4).... -
TX05C-R infrared surveillance alarm circuit is shown. It can be used for surveillance of walls, windows, doors and various restricted areas. If someone breaks into or over the alarm position, it will sound to play a security role. The circuit consists of.... -
The motorcycle anti-theft alarm which uses the 555 time-base integrated circuit is introduced in this article, and it can send out the alarm when the thief is moving the motorcycle vertically. The principle of the circuit The motorcycle anti-theft alarm.... -
The motorcycle anti-theft alarm is introduced in this article, it uses the private displacement sensor and has the features of high sensitivity, good reliability, low false alarm rate and easy to make. The principle of the circuit This motorcycle anti-theft.... -
This alarm siren circuit give continuous frequency sweep, a warbling sound. The warbling period is about 6 seconds, 3 seconds for frequency sweeping up and 3.... -
The MAXQ3210 ia a powerful RISC microcontroller. This device have features and capabilities to make it compatible for battery-powered applications that detect.... -
This is aquiz bell/alarm circuit. This circuit indicate fastest finger first . This circuit has one bulb for Quiz master and one for each contestant. The bulb will illuminate when a button is pressed. the cathode of the 9v1 zener sees approx mid-rail.... -
This schematic diagram shows a water level sensor/detector/monitor circuit. An alarm is also featured in this circuit. Any fluid with a resistance under 900K.... -
This schematic diagram below shows a 555 IC water level sensor/detector alarm circuit. This circuit is powered through the emitter current of the BC109C. 555 timer is used as astable oscillator in this circuit. When this circuit is under dry conditions the.... -
The circuit below is configured as a comparator. A fixed reference voltage at the non inverting input is provided by R1 and R2. The inverting input voltage is.... -
Unlike other alarm circuit that provide normally-open only or normally-closed only configuration, this alarm circuit work for both configurations. The....
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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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