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Digital alarm clock circuit diagram
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. U2 is the 7800 series regulator, its rated power can meet the requirements of the radio....
The LED display circuit diagram with flashing alarm
555 alarm doorbell and lighting controller circuit
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, automatic delay alarm, automatically turns off the lights and also it can be used as the...
Cashbox or Locker Alarm
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 standard reed switch. The circuit works off a 12V dc power supply.After construction, enclose...
House Alarm Loop
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..
Human infrared thermal release alarm
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, general-purpose sensor control circuit, high input impedance operational amplifier, it consists...
Infrared burglar alarm circuit schematic
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 40kHz high-frequency externally to form the IR beam. VDL is the infrared receiver probe,...
Triac gas - smoke alarm circuit schematic
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 through diode and 4.7k? resistor, so that VT1 gets conduction, then Triacs 2N6070A gets...
Water sensor alarm
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 integrated circuit is fixed with the help of R2.When pin 4 of the LM1801 voltage exceeds preset...
Car alarm circuit diagram
Domestic Seismic Alarm
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 away from IC1, IC1`s pin 3 outputs high level and VT is connected. HL is illuminated. IC2 and
Infrared alarm barrier circuit
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 light beam is interrupted by a person passing through it. Infrared Light Alarm Transmitter
Liquid level alarm circuit which controlled by integrated circuit promixity switches
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 after rectified, then control digital output level. When the sensor S dipped into the liquid,...
Motion Sensor Switch for alarm light or water sprinkler
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 Passive Infrared (PIR) Motion Sensor unit. Such units, packed in a compact enclosure with...
Motorcycle anti-thief alarm circuit (11)
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 mercury switch Sl, the resistors Rl-R3, the capacitor C, the transistors V1, V2 and the...
Motorcycle anti-thief alarm circuit (8)
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 7-91. The anti-theft detection circuit is composed of the piezoelectric vibration sensor BC,...
Auto Flash Alarm - Staircase_Control
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) internal NAND gate circuit D3, D4 and external RC components. Control circuit consists..
TX05C-R infrared surveillance alarm circuit
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 transmitter module, receiver module, time-base circuit, power circuit, the speaker and other...
The motorcycle anti-theft alarm (3)
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 circuit is composed of the trigger circuit and the alarm circuit, as the figure 7-85...
The motorcycle anti-theft alarm (4)
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 alarm circuit is composed of the integrated vibration displacement sensor (it is composed...
Wailing Alarm Siren
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..
Water Level Sensor/Alarm System for MAXQ3210 Controller
The MAXQ3210 ia a powerful RISC microcontroller. This device have features and capabilities to make it compatible for battery-powered applications that detect..
Fastest Quiz Bell/Alarm
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 voltage. The Quiz Master bulb is also illuminated. Here is the circuit: There is no other bulbs
Water Level Sensor/Detector/Monitor With Alarm
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..
555 IC Water Level Sensor/Detector Alarm
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 transistor will be fully off because it have no bias current. when the probes get wet, a sma
Temperature Alarm with Op-Amp Comparator
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..
Burglar Alarm Works for Both N.O and N.C Contacts
Unlike other alarm circuit that provide normally-open only or normally-closed only configuration, this alarm circuit work for both configurations. The..
Delayed Car Door Alarm
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..
Drive Safely wth Speed Alarm
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..
Surveillance Bug Circuits
Ultrasonic distance finder circuit
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 measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
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 find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
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 circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
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 circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
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, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
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 calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
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 supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
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. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
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