Top Circuits Page 208
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With this simple temperature to voltage converter circuit we can do a precise measurement of the temperature in a room. A NTC resistor or a thermistor is u....
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You can charge your Mobile Phone from the USB outlet of PC. This simple usb cellphone charger circuit can give regulated 4. 7 volts for charging the mobile phone. USB outlet can give 5 volts DC and 100 mA current which is sufficient for the slow charging of....
-
This flashing brake light circuit can be used for motorcycles. When brake-light switch S1 is closed, power is applied to U1 and U2. Two inverters of U2, a....
-
This simple electronic bicycle horn circuit uses only one gate of a 4093 quad 2-input NAND Schmitt trigger, U1, conected in a simple, low frequency, square....
-
A device to locate the mobile phone. It emits intermittent flashes and beeps to indicate the presence of an active mobile phone. The circuit becomes active even if the mobile phone is in silent mode. It can be used to detect mobile phone call in noisy....
-
With this electronic dice the result is displayed with LEDs that are placed so every dice face is shown. In the circuit diagram, IC 4022 is used to count t....
-
-
This flashing light circuit uses triacs to generate an intermittent light with variable frequency. Additional components are the D1 diode and semi adjustab....
-
Light your table top with this cool White LED Lamp. It is powered from the USB port and is ideal to take notes while browsing internet. The USB port can pr....
-
A simple tool to check the degree of radiation from an electric or electronic instrument. The LEDs in the circuit will give a running light pattern at the moment the circuit senses electromagnetic radiation from the device. It can detect radiation from the....
-
This mic preamp uses the low noise IC uA739. The circuit is an example of how a good preamplifier can be designed for dynamic microphones. The IC houses two identical integrated preamp circuits. The second preamp is used in identical manner for the second....
-
This circuit is useful to detect microwave (gigahertz signal) sources like microwave oven, satellite communication devices, Mobile phones etc. It gives audio visual indications when it detects the Microwaves in the Gigahertz band. Microwave is the form of EM....
-
-
This is a compact, easy to build amplifier that uses one IC only but delivers 40 watts of audio power. It is ideal for amplifying audio from your mobile CD player or iPod. The chip being used here is the TDA1514 originally brought to the market by....
-
This circuit generates inaudible ultrasound to make a barrier across the entry. At the moment the circuit detects a break in the sound barrier, it generates a loud alarm indicating the entry of a person. This can be used to protects the entry passages and....
-
Perhaps this is one of the simplest and smallest FM radio receiver that can receive the FM stations available locally. Its simple design makes it ideal for....
-
This shadow alarm circuit can sense a moving shadow in a confined area. It can be used to protect things from theft. When somebody approaches the unit, it will give a loud alarm to abort the attempt of theft. The circuit uses the light sensing property of....
-
TIP141 si a npn silicon power darlingtons designed for complementary use with TIP145, TIP146 and TP147. Can stand up to 125 W at 25 °C Case Temperature, 10 A Continuous Collector Current and has a minimum hFE of 1000 at 4 V, 5 A. This home audio amplifiercan....
-
Logic testers are simple but very helpful devices in testing digital circuits. A logic probe can be designed in many different ways. In this particular des....
-
This colorful back led aquarium lights gives natural appearance to the Aquarium tank. The Aquarium Led Lighting circuit automatically turns on at sunset an....
-
This simple circuit tells you about the status of phone such as Line OK, Dialing and Call attended. It also has a lock facility to block outgoing calls keeping the incoming calls as usual. This prevents misuse of telephone. The circuit uses only a few....
-
Transistors are inevitable parts of Electronic circuits. The success of a circuit design lies in the selection of proper transistor type and calculation of....
-
Field Effect Transistor is an amplifying device in which the output current depends on the input voltage. The FET Pre Amplifier described here is a sensiti....
-
This display driver circuit shows how a Seven Segment Display is driving with the help of the 5 stage Johnson decade counter IC CD4033.The IC has counter a....
-
This is the simple basic design of servo motor controller with pulse generator. It uses the CMOS IC 7555 in the Astable mode to generate pulses to drive th....
-
This Alarm will help you with its loud Police siren to abort the attempt of intrusion. With a single clap, the circuit generates the alarm for three minutes and then goes off. This is sufficient to catch the attention of neighbours. The circuit is a....
-
This is the simple and easy way to tap current from a Motor Bike battery to charge the Mobile Phone. Most of the Mobile Phone battery pack has three 1. 2 volt cells making the voltage to 3. 6 volts. For fast charging of the battery pack, each cell requires....
-
This motion detector alarm can detect a moving person from a distance of 1 meter. It uses a dual IR Transmitter-Receiver module HOA1405. When the sensor de....
-
As the name implies,emergency light is a source of light available during an emergency.It is an automatic system in which a rechargeable battery operated l....
-
This improved infrared detector is specifically intended for use with commercial IR remote control handsets. This little circuit is useful for quick go/no-....
-
This audio mixer circuit uses an LM3900 IC but is not a profesional audio dj mixer. The IC houses four integrated Norton amplifiers. The advantage of using the four op amps is that they only need a single power supply. Since this amplifier circuit is current....
-
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....
-
Here is a White LED Lamp that turns on when the telephone rings. The cool white light helps to locate the phone in darkness and also helps to note the mess....
-
This transformerless power supply circuit is designed for medium current applications. During the negative half period, the capacitor C5 is charged to peak....
-
This audio amplifier circuit is useful in classrooms to reduce the strain of lecturing, if the surrounding environment is noisy. It uses the power amplifier IC LM380 that gives 2 watts output which is sufficient in a confined area. The amplifier is portable....
-
The integrated chip LM386 is a low power audio frequency amplifier requiring a low level power supply (most often batteries). It comes in an 8-pin mini-DIP package. The IC is designed to deliver a voltage amplification of 20 without external add-on parts.....
-
Let`s construct a low-power FM transmitter using surface-mount devices (SMD) that will be received with a standard FM radio. Soldering surface mounted devi....
-
This circuit is used to simulate the police car lights by alternating flashing strobes seen on British police cars. The IC1a forms a square wave oscillator having adjustable frequency with VR1 to give the best effect. This square wave is buffered by IC1b and....
-
This is an AC powered LED flasher that can drive two High bright LEDs directly from the power obtained from the AC lines. The high bright LED flasher can b....
-
A monostable multivibrator using IC CD4538. It is a precision monostable/astable multivibrator IC free from false triggering. This can be used for various application in which precise timing cycle is required. CD4538 is the precision monostable/astable....
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A Simple Infrared controlled Switch. It can be operated using the TV remote handset. The Load can be any AC operated device which can be connected to the relay. The load turns on for three minutes then goes off. It can be used to switch on the lamp in the TV....
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Here is an energy saving solar inverter battery charger. It harvests solar energy to replenish 12 volt inverter battery. It has auto cut off facility to st....
-
LA4440 is a two channel audio power amplifier IC with inbuilt in dual channels enables it for stereo and bridge amplifier applications. In dual mode it giv....
-
Here is a simple circuit to protect your Telephone, EPBAX, Telephone Modem etc from lightning discharge or line spikes. It uses a safety capacitor and Gas....
-
An LCD basically consists of two glass plates with some liquid crystal material between them. The LCD has an electrically controlled light polarising liqui....
-
One of the major problems that is to be solved in an electronic circuit design is the production of low voltage DC power supply from Mains to power the cir....
-
Here is a Flasher circuit that directly derives power from AC to give brilliant flashes at the rate of one flash per second. It uses a Diac as the main ele....
-
Here is a crude but efficient tricky charger for Lead Acid Battery. It uses a 12 volt car bulb as current regulator and charge status indicator. The bright....
-
Touch controls are not only used to switch devices on or off. They can also be used to control different functions. One good example is the TV remote control. If it is very important to keep the activated functions for a long period of time, it is always....
-
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 is a 1 watt fm amplifier with a good design that can be used to amplify a rf signal in the 88 - 108 MHz band. It is very sensitive if you use good rf....
-
This automatic light dimmer circuit makes it possible to control a lighting system so that it turns on or off slowly. The circuit works this way: when switch S1 is closed, the capacitor C1 is slowly charged. Once the voltage at C1 reaches 0. 6, transistor T1....
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This time delay switch circuit is useful to switch on an AC load such as lamps after the delay of three minutes. This protects the load from inrush current and transients at power on which may be detrimental to the device. The time delay switch is directly....
-
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 led lamp circuit can be used as a mini led flashlight. Together with a 1.2 V rechargeable battery, all the components fit into a small enclosure. This....
-
This is a simple flashing led circuit with 2 leds and 2 NPN transistors. It illustrates the behavior of transistors and capacitors and if you use an oscill....
-
This electronic organ circuit is very simple to construct and is basically an emitter-coupled oscillator composed of T2 and T3. An squarewave voltage can be sampled from the collector of T3 (X2). This signal gives a clarinet character to the tone. An....
-
A Simple LED Voltmeter to Monitor the charge level in Lead Acid Battery or Tubular battery. The terminal voltage of the battery is indicated through a four level LED indicators. The nominal terminal voltage of a Lead Acid battery is 13. 8 volts and that of a....
-
This heatsink temperature monitor circuit signals via 3 LEDs when the temperature exceeds 2 boundary levels. When the heatsink temperature is below 50....
-
Maxim now has available a series of five integrated oscillator building blocks in the MAX260x series which cover the frequency range between 45 and 650 MHz. The MAX2606 covers the VHF band, although the frequency can only be varied by approximately ±3 MHz....
-
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 audio noise filter circuit is a bandpass filter for audio frequency band. It filters unwanted signals that are lower or higher than the audio frequenc....
-
CA3140 is the 4.5MHz BiMOS Operational Amplifier with MOSFET inputs and Bipolar output. This Op Amp combines the advantage of PMOS transistors and high vol....
-
The intercom schematic fulfills its tasks to provide a reliable communication line and is very simple to construct. The circuit is made up of an amplifier, two switches and two loudspeakers. If additional stations (speakers) are wished, additional switches....
-
The DIY Electronic Siren circuit described here can create three different US-style siren sounds: DIY police, DIY ambulance and fire engine. The desired sound can be selected using switch S1. The circuit can be used in toys (such as model vehicles), as part....
-
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....
-
This DIY magnetic field sensor circuit is very simple and can detect fixed magnetic fields or fields that are varying at an audio frequency. The unit is no....
-
This simple fm radio receiver circuit consists of a regenerative rf stage, TR1, followed by a two of three-stage audio amplifier, TR2 to TR4. In some areas....
-
This simple flashing light circuit is powered with 6 volts/0.5A and has a low current consumption when the light bulb is off. The flashing frequency is set....
-
Safe 12V car adapter described here can be used to limit a +12 volt car battery current, available from the in-dash cigar lighter power port, to below 2.6....
-
This small InfraRed Remote Control Tester circuit is used for checking the operation of an infrared remote control unit. The circuit is based on the idea of connecting a piezo buzzer directly to an IR receiver IC. The TSOP1738 integrated IR receiver accepts,....
-
Here is a simple toggle switch that can be operated through sound signals such as whistle or clap. The output of the toggle remains either low or high unti....
-
The 555 adjustable timer circuit starts timing when switched on. The green LED lights to show that timing is in progress. When the time period is over the....
-
The circuit featured here is very useful to save you from burning your tongue. The coffee thermometer is composed of a voltage regulator, a temperature to voltage converter, a comparator and two LEDs. Roughly described, the circuit works this way: if the....
-
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 Line Following Robot sensor or surface scanner for robots is a very simple, stamp-sized, short range (5-10mm) Infrared proximity detector wired around....
-
Install the PIR module hanging from a 3 metre high mast (to cover 10 metre radius area) and connect its supply and relay terminals to our finished and enclosed circuit, observing right polarity. A 4-core screened cable can be used for this interconnection.....
-
This Outdoor LED Solar Garden Lights project is a hobby circuit of an automatic garden light using a LDR and 6V/5W solar panel. During day time, the internal rechargeable 6 Volt SLA battery receives charging current from the connected solar panel through....
-
Minuscule circuit of the electric AC heater controller presented here is built around the renowned 3-Pin Integrated Temperature Sensor LM35 (IC1) from NSC ..
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Industrial grade clear glass sensor modules are widely available but not within the reach of an average electronics hobbyist. The simple clear glass sensor....
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A great collection of touch switch circuits. A touch switch is an electronic device that enables us to control a circuit by simply touching a sensor. The circuit as you can see from its diagram is very simple and only uses 8 components. The heart of the....
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This ultrasonic dog repeller circuit will chase away angry dogs. It is build with the all known 555 circuit, a buzzer and a little ferrite transformator. T....
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This ac to dc power supply can output 5A in continous operation and 12A peak current. This kind of dc power supplies uses a PCB so you can use two case typ....
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This two transistor AM radio circuit is also called ""mini-radio"". It uses only 2 transistors and few passive components which makes is very easy to be cons....
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CD 4047 is the low power Monostable / Astable Multivibrator that requires only an external capacitor and a resistor to give the output pulses. The values o....
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With the help of a simple ceramic piezo-electric detector it is possible to assemble an interesting and useful Impact sensor unit,which can be used to dete....
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This is a multifunction RJ45 network cable tester. It is the design of the network cable (RJ45) test, and telephone (RJ11). It is cheap and easy to use. It works for network, telephone, cable with RJ45 half Registered Jack plug immediately indicate whether....
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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....
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Moderately priced Passive Infrared PIR Sensor modules are now widely available. By using these readymade and pre-configured PIR sensors, even an average el....
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This sensitive FM radio tuner is the right circuit for hobbyists who want to build their own tuners instead of buying a ""plug-n-play"" finished product. The....
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The working principle of this cheap and easy to build metal detector circuit consists in mixing two equal frequencies which causes a low-frequency interfer....
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A continuously running cooling fan is a big nuisance and is not very crucial in most instruments. The 12V smart fan control presented here allows the fan t....
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This NiCd baterry charger circuit schematic can charge 6 volts as well as 12 volts NiCad batteries. It uses a transformer which can deliver 4 to 5 A curren....
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A simple battery charger for the Nickel Metal Hydride battery that requires current regulated charging. The charger provides 140 mA current for quick charging of the battery. Power supply section consists of a 0-18 volt AC 1 Ampere step-down transformer, a....
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Here is a 12 volt lead acid automatic battery charger that shut off the charging process once the battery attains full charge. This prevents overcharging o....
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This light sensitive circuit can operate a relay to switch on lamps or any AC loads when it senses darkness. It is ideal to use as switch less night lamps....
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AC mains operated single LED flasher circuit, built using the popular CMOS timer chip TLC555 is shown below. The whole circuit is powered directly by the grid supply of 230VAC through a capacitive potential divider and associated components. This minuscule....
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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....
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A subsonic filter is mostly used in low frequency technology. Most often, the very low frequencies create distorsions in music recording or reproduction. T....
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The panel 5W/6v Wp will have a max current of approx 500 to 800mA peaking at 800mA at noon. by restricting it to 150mA seems sheer waste. you can use a 1W panel to provide you 160mA at peak performance of 6 hours, to cover for the worst case scenario maybe....
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This analog switch circuit is designed to switch on or off and analog line. it consists of two analog switches in IC form that are controlled by two pushbu....
With this simple temperature to voltage converter circuit we can do a precise measurement of the temperature in a room. A NTC resistor or a thermistor is u....
You can charge your Mobile Phone from the USB outlet of PC. This simple usb cellphone charger circuit can give regulated 4. 7 volts for charging the mobile phone. USB outlet can give 5 volts DC and 100 mA current which is sufficient for the slow charging of....
This flashing brake light circuit can be used for motorcycles. When brake-light switch S1 is closed, power is applied to U1 and U2. Two inverters of U2, a....
This simple electronic bicycle horn circuit uses only one gate of a 4093 quad 2-input NAND Schmitt trigger, U1, conected in a simple, low frequency, square....
A device to locate the mobile phone. It emits intermittent flashes and beeps to indicate the presence of an active mobile phone. The circuit becomes active even if the mobile phone is in silent mode. It can be used to detect mobile phone call in noisy....
With this electronic dice the result is displayed with LEDs that are placed so every dice face is shown. In the circuit diagram, IC 4022 is used to count t....
This flashing light circuit uses triacs to generate an intermittent light with variable frequency. Additional components are the D1 diode and semi adjustab....
Light your table top with this cool White LED Lamp. It is powered from the USB port and is ideal to take notes while browsing internet. The USB port can pr....
A simple tool to check the degree of radiation from an electric or electronic instrument. The LEDs in the circuit will give a running light pattern at the moment the circuit senses electromagnetic radiation from the device. It can detect radiation from the....
This mic preamp uses the low noise IC uA739. The circuit is an example of how a good preamplifier can be designed for dynamic microphones. The IC houses two identical integrated preamp circuits. The second preamp is used in identical manner for the second....
This circuit is useful to detect microwave (gigahertz signal) sources like microwave oven, satellite communication devices, Mobile phones etc. It gives audio visual indications when it detects the Microwaves in the Gigahertz band. Microwave is the form of EM....
This is a compact, easy to build amplifier that uses one IC only but delivers 40 watts of audio power. It is ideal for amplifying audio from your mobile CD player or iPod. The chip being used here is the TDA1514 originally brought to the market by....
This circuit generates inaudible ultrasound to make a barrier across the entry. At the moment the circuit detects a break in the sound barrier, it generates a loud alarm indicating the entry of a person. This can be used to protects the entry passages and....
Perhaps this is one of the simplest and smallest FM radio receiver that can receive the FM stations available locally. Its simple design makes it ideal for....
This shadow alarm circuit can sense a moving shadow in a confined area. It can be used to protect things from theft. When somebody approaches the unit, it will give a loud alarm to abort the attempt of theft. The circuit uses the light sensing property of....
TIP141 si a npn silicon power darlingtons designed for complementary use with TIP145, TIP146 and TP147. Can stand up to 125 W at 25 °C Case Temperature, 10 A Continuous Collector Current and has a minimum hFE of 1000 at 4 V, 5 A. This home audio amplifiercan....
Logic testers are simple but very helpful devices in testing digital circuits. A logic probe can be designed in many different ways. In this particular des....
This colorful back led aquarium lights gives natural appearance to the Aquarium tank. The Aquarium Led Lighting circuit automatically turns on at sunset an....
This simple circuit tells you about the status of phone such as Line OK, Dialing and Call attended. It also has a lock facility to block outgoing calls keeping the incoming calls as usual. This prevents misuse of telephone. The circuit uses only a few....
Transistors are inevitable parts of Electronic circuits. The success of a circuit design lies in the selection of proper transistor type and calculation of....
Field Effect Transistor is an amplifying device in which the output current depends on the input voltage. The FET Pre Amplifier described here is a sensiti....
This display driver circuit shows how a Seven Segment Display is driving with the help of the 5 stage Johnson decade counter IC CD4033.The IC has counter a....
This is the simple basic design of servo motor controller with pulse generator. It uses the CMOS IC 7555 in the Astable mode to generate pulses to drive th....
This Alarm will help you with its loud Police siren to abort the attempt of intrusion. With a single clap, the circuit generates the alarm for three minutes and then goes off. This is sufficient to catch the attention of neighbours. The circuit is a....
This is the simple and easy way to tap current from a Motor Bike battery to charge the Mobile Phone. Most of the Mobile Phone battery pack has three 1. 2 volt cells making the voltage to 3. 6 volts. For fast charging of the battery pack, each cell requires....
This motion detector alarm can detect a moving person from a distance of 1 meter. It uses a dual IR Transmitter-Receiver module HOA1405. When the sensor de....
As the name implies,emergency light is a source of light available during an emergency.It is an automatic system in which a rechargeable battery operated l....
This improved infrared detector is specifically intended for use with commercial IR remote control handsets. This little circuit is useful for quick go/no-....
This audio mixer circuit uses an LM3900 IC but is not a profesional audio dj mixer. The IC houses four integrated Norton amplifiers. The advantage of using the four op amps is that they only need a single power supply. Since this amplifier circuit is current....
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....
Here is a White LED Lamp that turns on when the telephone rings. The cool white light helps to locate the phone in darkness and also helps to note the mess....
This transformerless power supply circuit is designed for medium current applications. During the negative half period, the capacitor C5 is charged to peak....
This audio amplifier circuit is useful in classrooms to reduce the strain of lecturing, if the surrounding environment is noisy. It uses the power amplifier IC LM380 that gives 2 watts output which is sufficient in a confined area. The amplifier is portable....
The integrated chip LM386 is a low power audio frequency amplifier requiring a low level power supply (most often batteries). It comes in an 8-pin mini-DIP package. The IC is designed to deliver a voltage amplification of 20 without external add-on parts.....
Let`s construct a low-power FM transmitter using surface-mount devices (SMD) that will be received with a standard FM radio. Soldering surface mounted devi....
This circuit is used to simulate the police car lights by alternating flashing strobes seen on British police cars. The IC1a forms a square wave oscillator having adjustable frequency with VR1 to give the best effect. This square wave is buffered by IC1b and....
This is an AC powered LED flasher that can drive two High bright LEDs directly from the power obtained from the AC lines. The high bright LED flasher can b....
A monostable multivibrator using IC CD4538. It is a precision monostable/astable multivibrator IC free from false triggering. This can be used for various application in which precise timing cycle is required. CD4538 is the precision monostable/astable....
A Simple Infrared controlled Switch. It can be operated using the TV remote handset. The Load can be any AC operated device which can be connected to the relay. The load turns on for three minutes then goes off. It can be used to switch on the lamp in the TV....
Here is an energy saving solar inverter battery charger. It harvests solar energy to replenish 12 volt inverter battery. It has auto cut off facility to st....
LA4440 is a two channel audio power amplifier IC with inbuilt in dual channels enables it for stereo and bridge amplifier applications. In dual mode it giv....
Here is a simple circuit to protect your Telephone, EPBAX, Telephone Modem etc from lightning discharge or line spikes. It uses a safety capacitor and Gas....
An LCD basically consists of two glass plates with some liquid crystal material between them. The LCD has an electrically controlled light polarising liqui....
One of the major problems that is to be solved in an electronic circuit design is the production of low voltage DC power supply from Mains to power the cir....
Here is a Flasher circuit that directly derives power from AC to give brilliant flashes at the rate of one flash per second. It uses a Diac as the main ele....
Here is a crude but efficient tricky charger for Lead Acid Battery. It uses a 12 volt car bulb as current regulator and charge status indicator. The bright....
Touch controls are not only used to switch devices on or off. They can also be used to control different functions. One good example is the TV remote control. If it is very important to keep the activated functions for a long period of time, it is always....
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 is a 1 watt fm amplifier with a good design that can be used to amplify a rf signal in the 88 - 108 MHz band. It is very sensitive if you use good rf....
This automatic light dimmer circuit makes it possible to control a lighting system so that it turns on or off slowly. The circuit works this way: when switch S1 is closed, the capacitor C1 is slowly charged. Once the voltage at C1 reaches 0. 6, transistor T1....
This time delay switch circuit is useful to switch on an AC load such as lamps after the delay of three minutes. This protects the load from inrush current and transients at power on which may be detrimental to the device. The time delay switch is directly....
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 led lamp circuit can be used as a mini led flashlight. Together with a 1.2 V rechargeable battery, all the components fit into a small enclosure. This....
This is a simple flashing led circuit with 2 leds and 2 NPN transistors. It illustrates the behavior of transistors and capacitors and if you use an oscill....
This electronic organ circuit is very simple to construct and is basically an emitter-coupled oscillator composed of T2 and T3. An squarewave voltage can be sampled from the collector of T3 (X2). This signal gives a clarinet character to the tone. An....
A Simple LED Voltmeter to Monitor the charge level in Lead Acid Battery or Tubular battery. The terminal voltage of the battery is indicated through a four level LED indicators. The nominal terminal voltage of a Lead Acid battery is 13. 8 volts and that of a....
This heatsink temperature monitor circuit signals via 3 LEDs when the temperature exceeds 2 boundary levels. When the heatsink temperature is below 50....
Maxim now has available a series of five integrated oscillator building blocks in the MAX260x series which cover the frequency range between 45 and 650 MHz. The MAX2606 covers the VHF band, although the frequency can only be varied by approximately ±3 MHz....
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 audio noise filter circuit is a bandpass filter for audio frequency band. It filters unwanted signals that are lower or higher than the audio frequenc....
CA3140 is the 4.5MHz BiMOS Operational Amplifier with MOSFET inputs and Bipolar output. This Op Amp combines the advantage of PMOS transistors and high vol....
The intercom schematic fulfills its tasks to provide a reliable communication line and is very simple to construct. The circuit is made up of an amplifier, two switches and two loudspeakers. If additional stations (speakers) are wished, additional switches....
The DIY Electronic Siren circuit described here can create three different US-style siren sounds: DIY police, DIY ambulance and fire engine. The desired sound can be selected using switch S1. The circuit can be used in toys (such as model vehicles), as part....
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....
This DIY magnetic field sensor circuit is very simple and can detect fixed magnetic fields or fields that are varying at an audio frequency. The unit is no....
This simple fm radio receiver circuit consists of a regenerative rf stage, TR1, followed by a two of three-stage audio amplifier, TR2 to TR4. In some areas....
This simple flashing light circuit is powered with 6 volts/0.5A and has a low current consumption when the light bulb is off. The flashing frequency is set....
Safe 12V car adapter described here can be used to limit a +12 volt car battery current, available from the in-dash cigar lighter power port, to below 2.6....
This small InfraRed Remote Control Tester circuit is used for checking the operation of an infrared remote control unit. The circuit is based on the idea of connecting a piezo buzzer directly to an IR receiver IC. The TSOP1738 integrated IR receiver accepts,....
Here is a simple toggle switch that can be operated through sound signals such as whistle or clap. The output of the toggle remains either low or high unti....
The 555 adjustable timer circuit starts timing when switched on. The green LED lights to show that timing is in progress. When the time period is over the....
The circuit featured here is very useful to save you from burning your tongue. The coffee thermometer is composed of a voltage regulator, a temperature to voltage converter, a comparator and two LEDs. Roughly described, the circuit works this way: if the....
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 Line Following Robot sensor or surface scanner for robots is a very simple, stamp-sized, short range (5-10mm) Infrared proximity detector wired around....
Install the PIR module hanging from a 3 metre high mast (to cover 10 metre radius area) and connect its supply and relay terminals to our finished and enclosed circuit, observing right polarity. A 4-core screened cable can be used for this interconnection.....
This Outdoor LED Solar Garden Lights project is a hobby circuit of an automatic garden light using a LDR and 6V/5W solar panel. During day time, the internal rechargeable 6 Volt SLA battery receives charging current from the connected solar panel through....
Minuscule circuit of the electric AC heater controller presented here is built around the renowned 3-Pin Integrated Temperature Sensor LM35 (IC1) from NSC ..
Industrial grade clear glass sensor modules are widely available but not within the reach of an average electronics hobbyist. The simple clear glass sensor....
A great collection of touch switch circuits. A touch switch is an electronic device that enables us to control a circuit by simply touching a sensor. The circuit as you can see from its diagram is very simple and only uses 8 components. The heart of the....
This ultrasonic dog repeller circuit will chase away angry dogs. It is build with the all known 555 circuit, a buzzer and a little ferrite transformator. T....
This ac to dc power supply can output 5A in continous operation and 12A peak current. This kind of dc power supplies uses a PCB so you can use two case typ....
This two transistor AM radio circuit is also called ""mini-radio"". It uses only 2 transistors and few passive components which makes is very easy to be cons....
CD 4047 is the low power Monostable / Astable Multivibrator that requires only an external capacitor and a resistor to give the output pulses. The values o....
With the help of a simple ceramic piezo-electric detector it is possible to assemble an interesting and useful Impact sensor unit,which can be used to dete....
This is a multifunction RJ45 network cable tester. It is the design of the network cable (RJ45) test, and telephone (RJ11). It is cheap and easy to use. It works for network, telephone, cable with RJ45 half Registered Jack plug immediately indicate whether....
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....
Moderately priced Passive Infrared PIR Sensor modules are now widely available. By using these readymade and pre-configured PIR sensors, even an average el....
This sensitive FM radio tuner is the right circuit for hobbyists who want to build their own tuners instead of buying a ""plug-n-play"" finished product. The....
The working principle of this cheap and easy to build metal detector circuit consists in mixing two equal frequencies which causes a low-frequency interfer....
A continuously running cooling fan is a big nuisance and is not very crucial in most instruments. The 12V smart fan control presented here allows the fan t....
This NiCd baterry charger circuit schematic can charge 6 volts as well as 12 volts NiCad batteries. It uses a transformer which can deliver 4 to 5 A curren....
A simple battery charger for the Nickel Metal Hydride battery that requires current regulated charging. The charger provides 140 mA current for quick charging of the battery. Power supply section consists of a 0-18 volt AC 1 Ampere step-down transformer, a....
Here is a 12 volt lead acid automatic battery charger that shut off the charging process once the battery attains full charge. This prevents overcharging o....
This light sensitive circuit can operate a relay to switch on lamps or any AC loads when it senses darkness. It is ideal to use as switch less night lamps....
AC mains operated single LED flasher circuit, built using the popular CMOS timer chip TLC555 is shown below. The whole circuit is powered directly by the grid supply of 230VAC through a capacitive potential divider and associated components. This minuscule....
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....
A subsonic filter is mostly used in low frequency technology. Most often, the very low frequencies create distorsions in music recording or reproduction. T....
The panel 5W/6v Wp will have a max current of approx 500 to 800mA peaking at 800mA at noon. by restricting it to 150mA seems sheer waste. you can use a 1W panel to provide you 160mA at peak performance of 6 hours, to cover for the worst case scenario maybe....
This analog switch circuit is designed to switch on or off and analog line. it consists of two analog switches in IC form that are controlled by two pushbu....