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8051 / 8052
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555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
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Digital & Bipolars
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Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Simple Proximity Detector & Alarm Circuit
This is a simple proximity switches with IC 4049th The IC4049 is a bipolar monolithic integrated circuit for use in metal-detection system / proximity sensing applications IC4049 includes an oscillator constituted by an external parallel resonant tank circuit and a feedback resistor connected 2-5 The internal oscillator operates near the resonant
Simple Small Portable Alarm Circuit
The system of using this circuit is positioning a little magnet close to the stalk switch SW1 while being connected to the hand or garments of the individual holding the sack with the use of a tiny cable. Since the circuit is tiny, it can be put in a tiny plastic box. The magnetic field will definitely loose its contact with the splint change the
Transmit output aid carrier alarm
Refrigerator Alarm Circuit
When the light falls on the LDR, it becomes low ohmic. The voltage at the junction of LDR/R2 charges the C2 via the R1 slowly. After about 10 seconds, the capacitor voltage reaches the input threshold of U1. Then U1 generates a square wave signal with a frequency of several Hertz. The time delay can be shortened by decreasing the value of R1 down
Smoke Alarm Circuit
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, easier to understand and has much better battery life. The photo-interrupter is simply an opti
Two-Zone Burglar Alarm
This is a two-zone alarm - with automatic exit, entry and siren cut-off timers. It can be triggered by the usual types of normally-closed input devices - such as magnetic reed contacts - foil tape - PIRs etc. I`ve used a 12-volt supply in the diagram - but the circuit will work at anything from 9 to 15-volts. All you need do is select a siren, buz
Car BackUp Alarm
The brake lights of the automobile trigger this circuit on and off. This save the annoyance of the alarm when it is not needed. This is an older circuit which was published in Popular Electronics Magazine, but still a good circuit today.
Circuit diagram for basic alarm with delayed trigger
The CD4001 quad 2-input NOR gate is a very versatile IC that can be used in an almost infinite variation. Here we will use it in the application of a simple alarm system. The power supply suggested for the CD4001 is 5 to 15Vdc Max. The CD4001 has a typical transition voltage value of 50% of its supply voltage with a possible spread of 30% to 70% d
Wireless alarm FM transmitter module
There are a lot of alarm systems on the market but you might be inclined to build your own. This little project can be put together using inexpensive parts readily available. The alarm transmitter module allows for a delayed trigger and auto turn-off as it is designed assuming that once the remote alarm has been triggered it will remain on until i
Design of a kind of simple and practical telephone alarm system
At present, it is numerous to adopt the telephone line as long-range control and alarm system of the transmission medium, associated too more research [1, 2 ]. This kind of system is generally made up of alarm device and calling the police to accept the receiving arrangement, computer of the centre etc. in the user. The alarm equipment finishes ju
Design on the basis of AT89C2051 intelligent automobile anticollision alarm equipment
With the quickening of the modern rhythm of life, the frequency happening in traffic accident is increasing too, in order to improve the safety that the car runs, this text introduces the mechanically controlled car anticollision alarm system of a one piece. This device combines real time control and data processing function of the one-chip comput
the remote intellectual pronunciation anti-theft alarm system design of the one-chip computer
Take precautions against the coefficient is low, the safety is bad, the applicable space is smaller and smaller. With the development of science and technology, people develop already the intersection of door and magnetic, touch-type, the intersection of radar and monitor, the intersection of infrared rays and the intersection of person who...
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. The transmitter and receiver circ
The frequency is controlled by the pin 5 of the IC. When the supply is switched ON, the capacitor charges slowly and this alters the voltage at pin 5 of the IC hence the frequenct gradually increases. After the capacitor is fully charged, the frequency no longer increases. Now when the push button siren control switch is held depressed, the capaci
Over-Temperature Alarm Circuit Uses Common Inexpensive Components
Over-Temperature Alarm Circuit Uses Common, Inexpensive Components | Negative-temperature-coefficient (NTC) thermistor, ICs.
Piezoelectric alarm rings clear as a bell
A common piezoelectric alarm, such as the Murata (Smyrna, GA) PKB5-3A shown, has many valuable attributes. It is compact, lightweight, efficient and reliable. However, the loud, high-pitched sound output can be quite irritating in many applications. The simple and inexpensive circuit provided here transforms this obnoxious little buzzer into a ple
transistors IR Emitter/Detector with 555 timer alarm
This circuit detects when a tube is empty and pulses a piezo buzzer in. 5 second intervals. I have it working with 5v on a breadboard, but I need to move it to 12v from a wall wart. Secondly, with 12v R1 should be 220 1W, but I want to stick with 1/4W resistors, maybe 510. Is that possible I realize that will bring down the 50ma current to...
Dummy Alarm Project
This Dummy Alarm project makes an LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. An on/off switch is not included, but could be added if you wish. The 7555 timer IC used is a low power version of
Light-sensitive Alarm Project
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 i
Water Activated Alarm
The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and emitter and the transistor switches on. A larger current flows in the collector circuit enabling
Advance Burglar alarm from dual-op amp
Device such as burglar alarms and sirens, whose basic purpose is to monitor tested circuit diagram with description of burglar alarm alarm using dual operational amplifier.
Digital Mains Failure/Resumption Alarm
Digital Mains Failure / Resumption Alarm use optocoupler and produce sound.circuit diagram with description of digital mains failure various alarm cirucit.
Fire Alarm Using Thermistor
Many fire alarm circuit is published in different website. But, here in this website is a simple and inexpensive project of fire alarm using thermistor. where thermistor is used astemperaturesensor of fire alarm. Working principle of thermistor is same as LDR (change their resistance with change in heat where LDR change their resistance with...
Fuse-Cum-Power Failure Indicator with alarm
Fuse Cum Power Failure Indicator employs thermister and timer IC NE555 circuit diagram with parts list of fuse cum power failure indicator indicate power failure.
Off timer with alarm with description
Off timer with alarm is a simple project used to indicate time off employs 4 transistor,.circuit diagram with parts list and description of off timer with alarm.various alarm project.
simple siren or alarm using MC1458 dual op-amp
simple siren or alarm using MC1458 dual op-amp and audio power amplifier LM380 circuit diagram with descriptions various siren, doorbell, alarm circuit with parts list.
Timer with musical alarm
Here timer with musical alarm is a electronics timer project using CD4060.delaying from 1 minute to 2 hour.circuit diagram of timer with musical alarm various electronics project.
Alarm LED Light Circuit
This circuit yearn for act the performance of the equipment, otherwise Check the fuse here the circuit. The circuit is diminutive and the power supply voltage of all kinds. It demonstrate with LED, 2-color in individual. Which is cathode universal kind, the anode has two separate terminals. If the circuit is functioning well LED, it revealed in...
PIC16F628 2 Input Alarm Circuit
The program uses the internal 4MHz oscillator PIC16F628 2 Input Alarm Circuit..
This is Fire Alarm using IC TD2002 suite, to identify if there is a fire. This alarm is very important in crowd residential complex, so that we can know earlier. This alarm works if there is a fog that generated by the fire cross the lamp and LDR sensor, so that the incoming light in LDR is reduced, this cause the resist in LDR is higher to genera
Earthquake alarm circuit schematic
Mini Alarm Circuit Schematic
This circuit, enclosed in a small plastic box, can be placed into a bag or handbag. A small magnet is placed close to the reed switch and connected to the hand or the clothes of the person carrying the bag by means of a tiny cord. If the bag is snatched abruptly, the magnet looses its contact with the reed switch, SW1 opens, the circuit starts osc
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
CMOS Circuits Tutorial