Circuit Diagram

Easy Build Motorcycle Alarm

Published:2013/3/25 4:16:00 Author:Ecco | Keyword: Easy Build Motorcycle, Alarm

The following circuit is a simple, cheap and easy build motorcycle alarm. The circuit just required 2 transistors to drive the relay the the relay act as a switch to activate the buzzer. Any number of normally-open switches may possibly be applied.   (View)

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Beeper Sound

Published:2013/3/25 4:16:00 Author:Ecco | Keyword: Beeper Sound

This is the circuit diagram of beeper sound. The circuit will generate the sound of a beeper which similar with the one in pagers. It produces a “beep-beep” sound. The work of this circuit is simple, the circuit applied the 555 timer oscillator which is turned ON and OFF periodically.   (View)

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Electronic Siren based NE555

Published:2013/3/25 4:04:00 Author:Ecco | Keyword: Electronic Siren

Here the circuit diagram of electronic siren based NE555. This circuit produces a sound like factory siren. It applies a 555 timer IC which is utilized as an astable multivibrator of a center frequency of about 300Hz. The frequency is controlled by the pin 5 of the IC.   (View)

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LPG Gas Leakage Sensor Alarm

Published:2013/3/25 4:03:00 Author:Ecco | Keyword: LPG Gas Leakage, Sensor, Alarm

This is the schematic diagram of LPG gas leakage sensor alarm. The circuit operates off a 9V PP3 battery. Zener diode ZD1 is applied to convert 9V into 5V DC to drive the gas sensor module. The SEN-1327 gas sensor module from RhydoLABZ is applied in this circuit. Its output goes higher when the gas amount reaches or exceeds specific point.   (View)

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Adjustable Analog Timer

Published:2013/3/25 4:02:00 Author:Ecco | Keyword: Adjustable Analog Timer

This is a very simple adjustable analog timer circuit diagram. You can build this circuit just for fun, for newbie project or may be…, this circuit could be used to set a time limit when playing games or as an egg-timer in the kitchen.   (View)

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Pyroelectric Fire Alarm System

Published:2013/3/25 4:02:00 Author:Ecco | Keyword: Pyroelectric , Fire Alarm System

This is definitely an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo component to recognize the fire. The lead zirconate titanate crystals within the piezo component have the property to deform and produce an electrical potential when heated, thus converting the piezo component into a heat sensor.   (View)

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Multitone Siren Alarm

Published:2013/3/25 4:01:00 Author:Ecco | Keyword: Multitone Siren Alarm

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.   (View)

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Heat Detector + Siren

Published:2013/3/25 3:49:00 Author:Ecco | Keyword: Heat Detector, Siren

This is the diagram of heat detector circuit which already integrated with siren circuit in the output. This circuit applies a complementary pair comprising NPN metallic transistor T1 (BC109) and PNP germanium transistor T2 (AC188) to detect heat (because of outbreak of fire, for example) in the area and activate a siren/alarm.   (View)

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Fire Alarm with LDR Sensor

Published:2013/3/25 3:48:00 Author:Ecco | Keyword: Fire Alarm , LDR Sensor

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 timely alarms are available. The circuit given right here alerts the user against these fire accidents.   (View)

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Cheap Motorcycle Alarm

Published:2013/3/25 3:47:00 Author:Ecco | Keyword: Cheap Motorcycle Alarm

This is simple to build and cheap motorcycle alarm circuit which could be fitted in motorcycles to take care of them from getting stolen. The tiny circuit may be hidden anyplace, without having any difficult wiring. Practically, it fits all motorcycles as long as they’ve a electric battery.   (View)

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Automatic Switch-Off Staircase Light

Published:2013/3/25 3:47:00 Author:Ecco | Keyword: Automatic Switch-Off Staircase, Light

This is the circuit diagram of staircase light with automatic switch off. It based on timer which is can be adjusted with the needs of the time of walking (climbing up and going down) on the staircase.   (View)

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Shutter Guard

Published:2013/3/25 3:45:00 Author:Ecco | Keyword: Shutter Guard

This is the shutter guard circuit which has sensitive vibration sensor, piezo-sensor. This circuit is specifically designed for outlets to defend towards theft. It can recognize any mechanical or acoustic vibration in its area when somebody attempts to break the shutter and instantly turn on a lamp and sound an alert alarm.   (View)

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Power Supply Failure Alarm

Published:2013/3/25 3:44:00 Author:Ecco | Keyword: Power Supply, Failure Alarm

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 requires no extra supply power source.   (View)

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Musical Bell with Touch Switch

Published:2013/3/25 3:43:00 Author:Ecco | Keyword: Musical Bell, Touch Switch

Here the circuit diagram of musical bell with touch switch and timer. This circuit is designed around CMOS IC CD4011 which work as the delay timer and IC UM66 which is well-known musical sound generator. When touch plates are bridged (touched) by hand for a moment, the circuit will start to produce music sound. Just after a short period (few seconds), the musical sound from this circuit will automatically stop.   (View)

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Notebook Anti Theft Protector

Published:2013/3/25 3:43:00 Author:Ecco | Keyword: Notebook, Anti Theft Protector

Here the notebook anti theft protector circuit to secure your important netbook / notebook from stealing. Basically, this is a mini security alarm generator. Fixed inside the notebook case, it will definitely sound a noisy alarm when a person attempts to grab the notebook. This very sensitive circuit utilizes a homemade tilt switch to turn on the alarm system through tilting of the laptop computer case.   (View)

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Meter/ Data Acquisition Amplifier

Published:2013/3/25 3:35:00 Author:Ecco | Keyword: Meter, Data, Acquisition Amplifier

The LM385-2.5 injects current into the summing node through an adjustable resistor with a value near 1 megohm. A good-quality fixed resistor near 900k and a 200k potentiometer would be a good combination. The zero pot is adjusted to get an output near -10 volts with the input grounded (assuming -10 volts is the negative limit of the data acquisition device - other offsets are possible). The gain will be near 5 with no gain set resistor, and will reach about 100 with a 41k resistor. The zero might vary slightly when the gain is changed. Use a good-quality 3.9 megohm resistor. Lower values may be used for all the gain-setting resistors.   (View)

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Class-A Audio Amplifiers

Published:2013/3/25 3:25:00 Author:Ecco | Keyword: Class-A Audio Amplifier

A class-A audio amplifier is pretty wasteful of power but when plenty of power is available the simplicity is attractive. Here is a simple darlington transistor example intended for use with a 5 volt power supply:   (View)

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Crystal Radio (and other purpose) Audio Amplifier

Published:2013/3/25 3:25:00 Author:Ecco | Keyword: Crystal Radio , Audio Amplifier

Here is a simple audio amplifier using a TL431 shunt regulator. The amplifier will provide room-filling volume from an ordinary crystal radio outfitted with a long-wire antenna and good ground. The circuitry is similar in complexity to a simple one-transistor radio but the performance is superior (with the exception of the amazing one-transistor reflex ). The TL431 is available in a TO-92 package and it looks like an ordinary transistor so your hobbyist friends will be impressed by the volume you are getting with only one transistor and the amplifier may be used for other projects, too. Higher impedance headphones and speakers may also be used. An earphone from an old telephone will give ear-splitting volume and great sensitivity! The 68 ohm resistor may be increased to several hundred ohms when using high impedance earphones to save battery power.   (View)

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Op-Amp Audio Amplifier

Published:2013/3/25 3:24:00 Author:Ecco | Keyword: Op-Amp Audio Amplifier

The above circuit is a versatile audio amplifier employing a low cost LM358 op-amp. The differential inputs give the amplifier excellent immunity to common-mode signals which are a common cause of amplifier instability. The dotted ground connection represents the wiring in a typical project illustrating how the ground sensing input can be connected to the ground at the source of the audio instead of at the amplifier where high currents are present. If the source is a power supply referenced signal then one of the amplifier inputs is connected to the positive supply. For example, an NPN common-emitter preamplifier may be added for very high gain and by connecting the differential inputs across the collector resistor instead of from collector to ground, destabilizing feedback via the power supply is greatly reduced.   (View)

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Computer Audio Booster

Published:2013/3/25 3:23:00 Author:Ecco | Keyword: Computer Audio Booster

Here is a simple amplifier for boosting the audio level from low-power sound cards or other audio sources driving small speakers like toys or small transistor radios. The circuit will deliver about 2 watts as shown. The parts are not critical and substitutions will usually work. The two 2.2 ohm resistors may be replaced with one 3.9 ohm resistor in either emitter.   (View)

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