Electronic Circuits and Diagram-Electronics Projects and Design

Seven Segment Counter Display Circuit Description Here is the circuit diagram of a seven segment counter based on the counter IC CD 4033.This circuit can be used in conjunction with various circuits where a counter to display the progress  adds some more attraction. IC NE 555 is wired as an astable multivibrator for triggering the CD 4033.For each pulse the out put of CD 4033 advances by one count.The output of CD 4033 is displayed by the seven segment LED display LT543.Switch S1 is used to initiate the counting.Diode D1 prevents the risk of accidental polarity reversal. Seven Segment Circuit…

Car Battery Voltmeter Circuit Description This is a very useful circuit which when installed on your car gives the voltage of you car battery in a LED dot display form.The circuit is based on four comparators made of quad op amp LM324.The inverting inputs of IC are kept at at reference voltages 5.6V,5.2V,4.8V,4.4V respectively at pins 2,6,9,13 by resistors ,R3,R4,R5,R6.The battery voltage is directly fed to the pin inverting input through the voltage divider arrangement using R1 and R7.When there is variation in the input supply the out put of each op amp goes high accordingly as they are wired…

Metal Detector Circuit Description This is the circuit diagram of a low cost metal detector using a single transistor circuit and an old pocket radio.This is nothing but a Colpitts oscillator working in the medium band frequency and a radio tuned to the same frequency.First the radio and the circuit are placed close.Then the radio is tuned so that there is no sound from radio.In this condition the radio and the circuit will be in same frequency and same frequencies beat off to produce no sound.This is the set up.When the metal detector circuit is placed near to a metal…

Lamp Flasher using NE 555 Description This is the circuit diagram of lamp flasher operated from mains. By this you can flash up to 200 Watt lamps at rates determined by you. IC NE555 is wired as an astable multivibrator for producing the pulses for flashing the lamp. The flashing rate can be set by the value of resistors R2 & R3. Diodes D1 & D2 provides a half wave rectified regulated supply for the IC. Transistor T1 is used to drive triac and triac BT136 for driving the load. Resistor R4 limits the base current of Q1. Flashing Circuit…

Melody Generator Circuit Description Here is a simple melody generator circuit you can make using an IC.The  UM66 series are CMOS IC’s  designed for using in calling bell, phone and toys. It has a built in ROM programmed for playing music. The device has very low power consumption.Thanks for the CMOS technology.The melody will be available at pin3 of UM66 and here it is amplified by using Q1 to drive the speaker.Resistor R1 limits the base current of Q1 within the safe values.Capacitor C1 is meant for noise suppression. Notes Power supply  must be between 1.5V & 4.5V .Do not…

Water Level Indicator Description This is the circuit diagram of a simple corrosion free water level indicator for home and industries. In fact the the level of any conductive non corrosive liquids can be measured using this circuit. The circuit is based on 5 transistor switches. Each transistor is switched on to drive the corresponding LED , when its base is supplied with current through the water through the electrode probes. One electrode probe is (F) with 6V AC is placed at the bottom of tank. Next probes are placed step by step above the bottom probe. When water is…

LED Emergency Light We have developed three circuits under Automatic LED Emergency Light. Two of them are designed by Mr. Seetharaman, a very valuable and important contributor of this website. We have listed the circuits here for your ease of  reading. If you have any doubts; please comment with circuit name or circuit number. 1. Simple Emergency Light using LED 2. Automatic Emergency Light using LM317 IC 3. Modified Version of Automatic LED Emergency Lamp using LM 317   1. Simple Emergency Light Circuit This is one of the most cost effective (cheap) and simple emergency light circuit developed for…

Stereo Amplifier Circuit Description Here is the circuit diagram of a  powerful and high quality stereo amplifier using IC TDA 1554.The circuit has only very few components.The circuit works best with a 4 Ohm speaker. TDA1554 is a 4 x 11 watt integrated Class-B audio amplifier from Phillips.Since the IC can be operated from 12V it finds a lot of application in car audio systems.The TDA1554 has a lot of good features like thermal protection, reverse polarity protection, load dump protection, short circuit to ground protection, excellent ripple rejection, no switch ON/OFF thud etc. The IC can be wired in…

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…

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…