Electronic Circuits and Diagram-Electronics Projects and Design

Digital Volume Control Circuit Description This is the circuit diagram of a digital volume controller for any sort of audio amplifiers or almost any circuit where a mechanical potentiometer is there(conditions apply). Simple and low cost, the heart of the circuit is DS 1669 digital potentiometer IC from Dallas Semiconductors.The circuit has no external components other than two pushbutton switches and a capacitor. Tips S 1 increases the volume & S2 decreases. The input audio signal must be not less than -0.2 Volts. If some clipping problem occurs, use a dual power supply of +5 & -5V.( Not shown in…

Touch Control Lamp Dimmer Description This is a simple touch dimmer circuit made of IC TT6061 . TT 6061 is specifically designed for this purpose.By touching this touch dimmer you can increase the light intensity of incandescent lamps in three steps At first, when mains  is ‘on,’ the lamp is ‘off’. When you touch the  plate, the lamp glows dimly. At second touch, the bulb gives medium light. On the third touch, the bulb is driven fully.Next touch puts off the light off. Line frequency is taken through R4 to pin 2 of IC.At zero crossing the IC fires a…

LED Thermometer – Temperature Measurement Circuit Description The circuit given here is a precision LED bar graph Fahrenheit thermometer,which can be used as a temperature measurement circuit, build around IC LM 34 (sensor) and IC LM 3914 (bar graph driver). The circuit can be modified to read in degree Celsius by replacing sensor LM 34 with LM 35. Both are inter changeable. The circuit operates of a volt power supply. To calibrate the circuit, you will need a voltmeter. Power the circuit . Ground the negative lead of the volt meter and connect the positive lead to pins 6 and…

Electronic Combination Lock Circuit Description This is the circuit diagram of a simple electronic combination lock using IC LS 7220.This circuit can be used to activate a relay for controlling (on & off) any device when a preset combination of 4 digits are pressed.The circuit can be operated from 5V to 12V. To set the combination connect the appropriate switches to pin 3,4,5 and 6 of the IC through the header.As an example if S1 is connected to pin 3, S2 to pin 4 , S3 to pin 5, S4 to pin 6 of the IC ,the combination will be…

Tone Generator Circuit Description Here we present a simple and low cost tone generator circuit, a ding dong bell suitable for calling bell purposes.It is made around IC 8021. It is an 8 pin IC but only four pins are shown here. 8021 has an in-built circuitry to produce ding dong sound each time its pin 3 is pulled low. The sound is stored in a 4 bit ROM. A complementary-pair, two-transistor amplifier is used to amplify the sound to a fair level of audibility. A piezoelectric tweeter or an 8-ohm, 500mW speaker  can be used at the output. Each…

Make a Digital Stop Watch Description A digital stop watch built around timer IC LM555 and 4-digit counter IC MM74C926  with multiplexed 7-segment LED display. MM74C926 consists of a 4-digit counter, an internal output latch, npn output sourcing drivers for common cathode, 7-segment display and an internal multiplexing circuitry with four multiplexing outputs. The counter advances on negative edge of the clock. The clock is generated by timer IC LM555. The circuit works off a 5V power supply. It can be easily assembled on a general-purpose PCB. Enclose the circuit in a metal box with provisions for four 7-segment displays,…

How to make an Inverter Description This is the schematic of a simple 40W , 12 volts to 220 Volts inverter.You don’t believe, this is simple and cheap and working for me for last 4 years.The heart of the circuit is a CD 4047 IC which is wired as an astable multi vibrator here.Resistance and Capacitance at pin 1&2 determines the out put frequency.Here it is set to 60Hz.Due to this a two 180 degree out of phase ,120 Hz , 50% duty cycle waveforms will appear at pin 10 & 11.These waves are amplified by the complementary symmetry amplifier…

How to make a simple Proximity detector or sensor Description This is a simple proximity detector using IC CS209. The CS209A is a bipolar monolithic integrated circuit for use in metal detection/proximity sensing applications.The CS209A contains an oscillator set up by an external parallel resonant tank and a feedback resistor connected between pin 2 & 3 .The internal oscillator operates close to the resonant frequency of the tank circuit.As a metal object is brought close to the inductor, the amplitude of the voltage across the tank gradually begins to drop. When the envelope of the oscillation reaches a certain level,…

How to make a long range FM transmitter at low cost Description The use of transmitters which have a more powerful output than the ‘flea-power’ are sometimes required when there are many obstacles in the path of the surveillance transmitter and monitoring station receiver, or the distance between them is too far so as to make a low powered device feasible. Whereas a typical micro transmitter will produce an RF power in the order of just a few milliwatts, i.e. a few thousandths of a watt, the VHF-FM transmitter described has a power output of between around a half and 2 watts, depending on the power source, which…