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. This circuit will produce a visual as well as audible alert whenever the connection between the charger circuit and the battery being charged.What ever be the situation whether it be a loose contact or breakage the circuit will give you the alarm.Such a circuit can be very handy in the fail safe charging of the batteries
Description. Here is a simple charger circuit for charging SMF(sealed maintenance free ) batteries.The charger circuit being curernt and voltage regulated,can be safely used to charge SMF batteries of 1.2 AH rating.This circuit was actually designed in response to a request from a reader.With slight modifications you can use it for charging any sort of
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. This circuit can give a visual indication of the rate of air flow.It can be also used to check whether there is air flow in a given space. The filament of a incandescent bulb is the sensing part of the circuit.When there is no air flow the resistance of the filament will be low.When
Description. This circuit can be used to glow a bulb or turn a alarm when the phone rings.Using this circuit nuissence of telephone ring at night can be avoided. When the telephone rings the line voltage rises to 72 volts.At this time the LED in the opto-coupler glows and the transistor conducts. Due to this
 Description. Low power ( 3 to 30 MHz) transmitters constructed by hams are generally called QRP’s. For such transmitters a well tuned antenna is a must.If the impedance is not properly matched there will be a little or no output.But if properly matched there will be great results.A circuit for matching the antenna properly with
 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. This micro flasher circuit continuously emits flashing light with the consumption of very less power.The circuit can run for a very long time for four 1.5 V torch cells. Here a low power CMOS IC CD4093 (IC1) is used to produce sharp pulses of 20 ms from a red LED.The LED appears to
Description. Here is a simple circuit for boosting 12 V DC to 24 V DC .The circuit is designed straight forward and uses few components.With few modifications the circuit can be used to boost any voltages. The transistor Q1 and Q2 (D1616) essentially drives the primary of the transformer.The diodes rectifies the output of transformer
 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. The IR to RF transmitter circuit given here can convert the IR signals from your remote to RF signals to long distances. The circuit given here is a good one for extending the range of your IR remote.Also such systems does not need a line of sight since RF signals are used. The transmitter
 Description. The automatic door handle alarm circuit gives a audible alarm and glows a LED when somebody touches the handle of the door.The circuit is latching type and continues to produce sound until it is switched off. The transistor Q1 is wired as an astable multivibrator whose output is used to bias transistor Q2 to
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. Here is a simple and compact flasher circuit that an be used where ever a flashing LED is needed.The circuit finds application in flashing beacons,alarms automobile and more. The circuit is nothing but an astable multivibrator based on IC NE 555 (IC1).The frequency of the oscillation depends on the values of R1,R2 ,R3 and
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. Here is a handy field strength meter that can be used to check the strength of AM radio signals.The circuit is a very useful for those who assemble radio transmitters(especially in the tuning of the final stage for maximum range). The circuit is essentially some sort of a AM receiver it self. The capacitor
Description. Here is the schematic of a simple flouroscent lamp driver circuit based on two transistors.The circuit uses capacitive ballasting for driving the tube.An 8 W standard flouroscent tube can be efficiently driven using the circuit. The two transistors (2Sc 1983) with associated components forms a oscillator around 1KHz.The oscillator is wired so that saturation
Description. Here is the circuit diagram of a versatile FM transmitter that doesn’t have a coil. The circuit is simple and easy to assemble. The gate N1 acts as a buffer for strengthening the signals from the condenser microphone. The inverter N2 with its associated components forms a radio frequency oscillator in the FM region.The
Description. Here is the circuit diagram of a magnetic proximity switch that finds a lot of applications in many fields.The circuit is based on a magnetic reed switch(S1) as the proximity sensor. A monostable multivibrator based on NE555 (IC1) and a toggle flip flop based on CD4013 (IC2) does the rest of the circuit. When
Description. A simple telephone transmitter circuit that is ideal for transmitting the telephone conversation through small distances.The circuit is very simple and uses only few components.The entire circuit can be easily included in the telephone itself or in the junction box.The circuit is powered from the telephone line itself. The transistor Q2 is wired as
