Electronic Circuits and Diagram-Electronics Projects and Design

Function Generator Circuit Description. The ICL8038 is a function generator chip, capable of generating triangular, square , sine, pulse and sawtooth waveforms . From these sine, square & triangular wave forms can be made simultaneously.There is an option to control the parameters like frequency,duty cycle and distortion of these functions.This is the best function generator circuit for a beginner to start with and is of course a must on the work bench of an electronics hobbyist.The circuit here is designed to produce waveforms from 20Hz to 20 kHz.The ICL 8038 has to be operated from a dual power supply. Function…

Lead Acid Battery Charger Description Here is a lead acid battery charger circuit using IC LM 317.The IC here provides the correct charging voltage for the battery.A battery must be charged with 1/10 its Ah value.This charging circuit is designed based on this fact.The charging current for the battery is controlled by Q1 ,R1,R4 and R5. Potentiometer R5 can be used to set the charging current.As the battery gets charged the the current through R1 increases .This changes the conduction of Q1.Since collector of Q1 is connected to adjust pin of IC LM 317 the voltage at the output of…

Multi Tone Alarm Description This is a simple and easy to build multi tone alarm circuit that can be used in burglar alarms or sirens. The circuit is based on dual op amp MC1458 and  LM 380. The two op amps inside the MC 1458 are used to produce square and triangular waves.LM 380 is used to amplify the output.The first op amp IC1a is wired as an astable multi vibrator and second op amp IC1b is wired as an integrator , to make the square wave triangle. The two output square ans sine can be selected using switch S1…

Audio Distortion Meter Description Here is a simple 1KHz audio distortion meter that can measure the Total Harmonic Distortion (THD) on any load at any out put power.Here you have the option to select 2,4,8 or 16 Ohm loads. The circuit works by filtering the 1 kHz fundamental signal using a notch filter comprising of L1,C2,C1,R1. With a little time and calculation you can get the correct THD of your amplifier in such a simple way. Audio Distortion Meter Circuit Diagram with Parts List . Notes Inductor L1 is a UTC VC 15 variable inductor.If this is not available try…

Simple Sound Generator Circuit Description This is a real scream generator circuit suitable for any purpose like alarm or car horn.The circuit is based on two transistors Q1 and Q2.When you press the switch S2 the siren starts up moving to a high frequency.When the switch is released the tone slips down until you shift it up again by pushing the switch S2. Sound Generator Circuit Diagram with Parts List. Notes. Adjustment of tone quality can be obtained by different values for C2. If the alarm oscillates before S2 is pressed.The transistor is leaky, replace it. S1 can be used…

Audio Watt Meter Description This is an easy trick to measure the output of an amplifier.Here resistor R2 acts as the load for for the amp and it should be able to withstand twice the maximum power of the amp you are going to measure.The meter scale must be calibrated and with a little effort you can get good results. Audio Watt meter Circuit Diagram with Parts List. Notes If 1A bridge is not available , make one with four 1N 4007  Diodes. The resistor R2 must be twice the power of amp you are going to measure. To calibrate …

Intruder Alarm Circuit Description Here is  the circuit diagram of an ultra sensitive intruder alarm. The shadow of an intruder passing few meters nearby the circuit is enough to trigger the alarm. Here IC2 uA 741 is wired as a sensitive comparator ,whose set point is set by R6 &R7. The  voltage divide by LDR and R9 is given at non inverting pin of IC2. At standby mode these two voltages are set equal by adjusting R9. Now the output (pin6) of comparator will be high.Transistor Q1 will be off. The voltage at trigger pin of IC1 will be positive…

Single Chip FM Radio Description. Here is a compact low cost FM radio circuit using IC TDA 7000. This circuit is designed as per the data sheet and the result is excellent.Ideal for all category of electronic enthusiasts. The TDA7000 is a monolithic integrated circuit for mono FM portable radios, where a minimum on peripheral components is crucial. The IC TDA 7000 has a Frequency-Locked-Loop system with an intermediate frequency of 70 kHz. The intermediate frequency selectivity is achieved by active RC filters. The only function which needs alignment is the resonant circuit for the oscillator, thus selecting the reception…

Direct Coupled Radio Circuit Description Here is the circuit of an excellent direct coupled radio ideal for listening to near by stations.The circuit uses Q1 as a diode detector and first audio amplifier.The detection is across the first emitter base junction which operates as a diode.The base emitter capacitance provides the radio filtering.The resistor R1 is adjusted to obtain the least distortion with consistent volume.Transistors Q2 and Q3 also serve as audio amplifiers. Radio Circuit Diagram with Parts List Notes For L1 use a center tapped ferrite antenna coil used AM receivers. Battery is advised to power the circuit to …

Liquid Level Switch Description Here is a simple level switch circuit that switches on one relay and switches off another relay when the fluid level exceeds the set limit.This circuit is a modification of the Simple Water Level Indicator previously posted.When the water level touches the probes positive supply is connected to the base of Q1 through fluid.This makes transistor Q1 ON.Base of Q2 is connected to collector of Q1 and base of Q3 is connected to collector of Q2.As a result Q1 will be on and Q2 will be OFF.So K2 will be OFF and K1 will be ON.Net…