Description. An NE555 timer IC connected as shown here can detect a missing pulse or abnormally long period between two consecutive pulses in a train of pulses. Such circuits can be used to detect the intermittent firing of the spark plug of an automobile or to monitor the heart beat of a sick patient. The […]
Description. This circuit is a compact timer circuit that will keep the headlights of your car ON for about 1.5 minutes and then turns it OFF.This circuit incorporated to your car will help you to access dark places with out the need to come back and turn OFF the head lights. When the push button
Description. This simple circuit that can be used to flash incandescent lamps up to 10W power rating.The circuit is ideal for making flashing beacons on automobiles and other applications like that.The circuit is nothing but an astable multi vibrator based on Q1&Q2 ( BC557&BD139).The capacitor C1 is the main timing element which determines the flashing
Description. With this compact FM adaptor circuit plugged into the audio out of your cassete player or i Pod out put,you can listen your favorite music on your car stereo.This circuit is very useful if your car stereo doesnot have an auxillary in socket.The circuit is nothing buy an short range  FM transimitter. The FM
Description. This is a compact electronic siren circuit based on three transistors.This circuit is suitable for in corporating with other alarm or siren projects such as burglar alarms, automatic factory sirens etc or a simple push to on alarm. The electronic siren circuit given here  is based on a complementary transistor pair consisting of Q2
Description. Here is a simple water level alarm circuit using 555 timer that will produce an audible alarm when the water level reaches a preset level.The circuit can be powered of a 3V battery and is very handy to use. The circuit is based on an astable multivibrator wired around IC1 (NE 555).The operating frequency
Description. Here is a simple and effective circuit for driving florescent lamps from a 12 V supply.The circuit is nothing but consists of an oscillator, a MOSFET switch and a step-up transformer for driving the florescent lamp. The IC1 TLC 555 is wired as an astable multivibrator for producing the necessary oscillations.The MOSFET Q1 is
Description. Here is a simple head phone amplifier circuit that can be used to drive your head phone if your music player doesn’t have enough power to drive your head phones.The circuit is straight forward and uses only three transistors. The transistor Q1 (BC 239) and associated components forms a pre amplifier.The transistor pairs Q2
Description. Here is a simple circuit that can be used to check the sound levels.The sound pressure meter is vey useful in setting up home theater systems , if you need to test the sound pressure of each channels on different positions in the room. The circuit is nothing but a non- inverting amplifier based
Description. This circuit given here can be housed in the box containing the speaker to form a handy microphone amplifier.The device can be used by teachers,guides,lecturers etc for speaking in a crowdy or noisy environment. The circuit is designed base on the audio power amplifier IC TDA 7052.The IC can deliver a maximum power output
Description. The contact less telephone ringer circuit can produce a ring as well as a visual indication when a call comes.The main advantage is that since there is no direct contact between the phone line and the circuit there is no chance for a loading or disturbance in the telephone line. When the telephone
Description. This circuit can be used to escape from the nuisance of mobile phone rings when you are at home. This circuit will give a visual indication if placed near a mobile phone even if the ringer is deactivated. When a call is coming to the mobile phone, the transmitter inside it becomes activated. TheÂ
 Description. Here is a simple shock sensitive alarm circuit that has many many applications fro home to automobiles.The main application of this circuit is to use it as an anti theft alarm in automobiles.A peizo electric sensor is used as the shock sensor which has to mounted on the door which you have to protect.
 Description. Here is superb sound shifter circuit that can be used to add effects to the input sound signal.The circuit is ideal for incorporating in toys and adds great fun.The circuit can be also used in mixers and recorders. The circuit is based on IC HT 8950 from Holtek. The IC HT8905 is a single
Description. Here is a simple 3 band graphic equalizer circuit made of a single op amp IC LF351 (IC1) and few passive components.The component values of this circuit are not very critical and can be replaced with nearest values with a little loss on the performance.This feature make it easy to be assembled from your
Description. A very rugged and reasonably power amplifier circuit that can be used for any audio applications. The amplifier produces 60W rms at 50V supply on a 8 Ohm load.The circuit is designed such that most of the components are not critical and can be easily replaced by nearest values.This make it ideal to assemble
Description. With this cool circuit integrated to your cars headlight system , you can drive cool headed in high beam.The circuit will take over the duty of low beaming the headlight when vehicles approach against , and high beams the lights when they pass over. The circuit is based on a photo transistor(Q1) for sensing
Description. The circuit depicted here can be used as an indicator when the telephone receiver is off-hook. The circuit can be in corporated with old telephones that does not have such an indicator. The circuit uses a complementary darling to pair using Q1 (2N3904)and Q2 (2n3906) to sense whether the receiver is off hook and
Description. Many fire alarm circuits are presented here,but this time a new circuit using a thermistor and a timer to do the trick. The circuit is as simple and straight forward so that, it can be easily implemented. The thermistor offers a low resistance at high temperature and high resistance at low temperature. This phenomenon
Description. The circuit diagram present here is that of a street light that automatically switches ON when the night falls and turns OFF when the sun rises. In fact you can this circuit for implementing any type of automatic night light. The circuit uses a Light Dependent Resistor (LDR) to sense the light .When there
Description. No big deal here! You can make a decent power amplifier using just three transistors. All components used here can be obtained from your electronic junk box. Also you just need a 9V transistor radio battery to power this circuit. The circuit is ideal for a pocket radio or other hand held audio equipments.
Description. Here is the simplest scheme for converting a CD ROM drive of your computer to a Audio CD player. The minimum requirement for the player is that, it should have a audio output and skip button. Luckily most of the CD ROM’s are equipped with both of these. Â The CD ROM drive needs two
Description. Here is a simple fire alarm circuit based on a Light Dependent Resistor (LDR) and lamp pair for sensing the fire. The alarm works by sensing the smoke produced during fire. The circuit produces an audible alarm when the fire breaks out with smoke. When there is no smoke the light from the bulb
Description. This straight forward circuit will protect electrical appliances from over voltage as well as under voltage. The circuit also produces an alarm when the power supply comes back. An ideal circuit for home to protect your valuable equipments from voltage fluctuations. The same circuit with some modifications can be used to make a automatic
How to make a 12V battery charger at home? Description Here is the circuit diagram of a simple and straight forward 12 V battery charger circuit with diagram. This circuit can be used to charge all type of 12V rechargeable batteries including car batteries. The circuit is nothing but a 12V DC power supply with
