Description. This is a simple LED torch circuit based on IC MAX660 from MAXIM semiconductors. The MAX 660 is a CMOS type monolithic type voltage converter IC. The IC can easily drive three extra bright white LEDs.The LEDs are connected in parallel to the output pin 8 of the IC. The circuit has good battery […]
Description. Here is the circuit diagram of an ultrasonic mosquito repeller.The circuit is based on the theory that insects like mosquito can be repelled by using sound frequencies in the ultrasonic (above 20KHz) range.The circuit is nothing but a PLL IC CMOS 4047 wired as an oscillator working at 22KHz.A complementary symmetry amplifier consisting of
Description. Here is a simple heater circuit that can be operated from a 12V battery. The first part of the circuit is an astable multivibrator build around the two transistors Q1 and Q2 .The ON time of transistor Q2 is set to 0.5 S. The ON time of transistor Q1 can be varied by using
Description. This is the circuit diagram of a fully transistorized sub woofer amplifier that can produce an output of 100W.There are seven transistors including four in the output stage. The transistors Q1 and Q2 form the preamplifier stage. Transistors Q4 to Q7 form the output stage. Since no ICs are used the circuit is very
Description. This circuit produces a musical tone whenever someone touches the touch point designated as TP in the circuit. The circuit works from two AA cells and produces enough sound. The circuit uses IC UM 3481 commonly used in musical circuits. The IC contains a ROM with 512 musical notes, tone generator, rhythm generator, modulator,
Description. Here is a simple circuit that will give a visual indication when the soil water level inside your flower pot goes low below a certain limit. The U1C and associated components are wired as an oscillator producing a 2KHz square wave. This square wave is given to one gate input of U1D via a
If you are looking for a Water level indicator or a Water level controller, there are pretty good circuits we have developed. This one is just a fun project made for hobby purpose! You can call this a water sensor circuit for sure! Description. This is a simple musical alarm circuit which produces a musical
Description. Â Here is a simple circuit switches on a light around 2 hours after midnight, the time at which most of the robberies taking place. This simple circuit is build around a CMOS IC 4060 to obtain the required timing. During day time the LDR has low resistance and keeps the pin 12 of the
Description. This is a simple circuit that can be used as a sequential signal light in automobiles. The circuit is based on two ICs. A TS 555 CN CMOS timer IC and a CD4017 decade counter IC. The IC1 is wired as an astable multivibrator to trigger the counter IC. When triggered, the outputs of
Description. Here is a simple but effective intercom circuit that is based fully on transistors.The circuit is based on a three stage RC coupled amplifier. When the pushbutton S2 is pressed, the amplifier circuit wired around T1 & T2 becomes an astable multivibrator and starts producing the ringing signals. These ringing signals will be amplified
Description. Here is a versatile remote controlled appliance switch that can ON or OFF any appliance connected to it using a TV remote. Â IR remote sensor IC TSOP 1738 is used for recieving the signal. Normally when no signal is falling on IC3 the output of it will be high.This makes Q1 OFF.When a signal
Descrption. This is a simple circuit in which the glowing LED can be switched OFF just by a puff. A condenser mic (M1) is used to sense your puff. When the push button S1 is pressed, the transistors Q2 and Q3 wired as latching pair gets activated and drives the LED to glow. The LED
Description. This simple circuit can be used as an aid for sensing the distance between the rear bumper of the car and any obstacle behind the car. The distance can be understood from the combination of the LEDs (D5 to D7) glowing. At 25cm D7 will glow, at 20 cm D7&D6 will glow and at
Description. Here is a simple yet powerful circuit that can be used for flashing 12V lamps especially that is used on automobiles.The flashing circuit is based on transistor Q1(BC557) and MOSFET Q2 (IRF530) where the Q2 provides the necessary drive for the lamp.Any number of bulbs can be flashed using this circuit provided that the
Description. This timer circuit can be used to switch OFF a particular device after around 35 minutes. The circuit can be used to switch OFF devices like radio, TV, fan, pump etc after a preset time of 35 minutes. Such a circuit can surely save a lot of power. The circuit is based on quad
Description. This circuit can be used to identify whether there is a clipping in a particular wave form. Clipping is a phenomenon in which the amplitude of a particular waveform drops before it reaches the expected limit. This circuit glows an LED as an indication if the signal under test has clipping. The circuit is
Description. Here is a simple circuit that will produce a musical horn when ever your car is in reverse gear.The circuit uses two ICs for the operation, voltage regulator 7805(IC1) and musical tone generator UM66(IC2). The IC1 reduces the car battery voltage to 5V. The diodes D1 & D2 in combination produces an additional drop
Description. Here is a simple circuit using IC NE555 that can be used to generate metronomes.Such a circuit is very useful to those who learns music. The circuit is nothing but an astable multivibrator wired around NE555 .The components R1,R2&C1 determines the output frequency. Circuit diagram with Parts list. Notes. The circuit can be wired
 Description. Here is a simple circuit diagram of a simple musical horn using two NE555 ICs. Two ICs are wired as astable mutivibrators. The output of first multivibrator is given to the discharge (pin 7) of the second astable multivibrator. The combined effect of the astable multivibrators produces a musical tone at the output.  Circuit
Description. A high gain amplifier circuit that can be operated from a battery pack of 6 or 9 volt battery pack is shown here.The IC1 uA 741 is wired as a high gain non-inverting amplifier and its output is amplified by a pair of complementary transistors (Q1 & Q2) to drive the speaker.The negative feedback
Description. A preamplifier circuit suitable for high impedance type electric guitar pickups is given here.The circuit is based on a uA 741 op-amp (IC1).The IC1 is wired as a non-inverting amplifier.The POT R1 can be used as a volume controller.The POT R6 can be used as tone controller.The switch S1 is used to produce “brilliant”
Description. A preamplifier for magnetic pickups of record players is shown here.The uA 741 is used as an AC coupled non-inverting amplifier operating on a single supply.The amplifier gain is decided by the feedback components in which C2 controls the low frequency roll-off characteristics while C4 reduces the gain at high frequency end to compensate
Description. A preamplifier operating on a single supply and suitable for use with high impedance type crystal pickups is shown here.The circuit is basically a non-inverting AC amplifier in which the gain is dependent on the feedback resistor R4.The smaller is the R4,the lower will be the gain.The low frequency roll off characteristics are decided
Description. The main part of this doorbell circuit are two NE555 timer ICs.When some one presses switch S1 momentarily, the loud speaker sounds a bell tone as long as the time period of the monostable multivibrator built around IC1. When the switch S1 pressed, IC1 is triggered at its pin 2 and output pin 3
Description. Just about any power transistor can be used in this megaphone.Its suitable for boats,playing fields etc.the transistors Q1 & Q2 are the HEP-230 type which are easily available in the market.The transistors are parallely connected to handle the required power and speaker matching.The microphone is a carbon type like that used in telephone hand
