Electronic Circuits and Diagram-Electronics Projects and Design

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…

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…

Doorbell Circuit Description Here is a simple and easy to build doorbell circuit using IC UM 66.The  details of UM 66  is given in the older post “Melody Generator using UM 66″. This is a slight modification of that circuit.In the previous circuit you have to keep the switch pressed for making the IC play the full music.Here if once the push button is pressed C1 is charged and the transistor Q2 will keep the IC playing the music till it ends.The time for the IC to play depends on discharging time of C1  which can be set by R1.Set…

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…

Touch Switch Circuit using NE 555 Description This is the circuit diagram of a small touch plate controller using IC NE 555 .This circuit is ideally useful for making touch operated doorbells, buzzers,toys etc which when touched on the touch plate operates the relay for a preset time and the turns off automatically. This circuit is realized by utilizing the high input impedance of trigger pin of the 555 IC.When  the IC is triggered by the induced voltage of human body the output goes high for a time determined by R1 and C1.The transistor is used to drive the relay.The…

Automatic Wiper Control Description A continuously working wiper is a big problem when it is raining slightly.The wiper control given here makes the wiper to sweep at rates from 1S to 10 S. The circuit is build around an astable multivibrator using NE 555.Here the output at pin 3 remains high for a time period set by R2 ,and low for a time period set by R3.The low output pulse drives the transistor pair to drive the wiper motor to make one sweeping cycle and waits for next low pulse to arrive for next sweep.The high going pulse at pin…

Simple Radio Circuit Description This is a low cost simple radio circuit  based on op amp which can be used to listen to nearby stations. A simple op-amp radio basically consists of a crystal radio along with a fairly sensitive audio amplifier. The audio amplifier is able to receive strong stations around Los Angeles with a minimal 15 foot antenna. Stronger signals are always provided by longer antennas.But the main disadvantage is that in the case of long antennas the stronger signals provided may produce a noise as it could be heard in the background of the weaker signals. In…

Power Supply Circuit-40 Volts-2A Description. This is a power supply circuit diagram of 40Volts, that is able to deliver 2A current.This circuit is suitable for power amplifiers .Transistor TIP 42 A is used as a pass transistor to increase the current capabilities.Voltage regulator LM 317 is the heart of this circuit .Here the out put voltage is set to 40 V by R5 & R8.If you want any other out put voltage use a 10 K pot instead of R5 and adjust it. Parts List. R1_______________3R9 1 or 2W Resistor R2______________   22R  1/4W Resistor R3_______________6K8 1/4W Resistor R4_____________     220R  1/4W…

19 Watts Simple Amplifier Circuit Description This is a 19 watt simple amplifier circuit diagram using IC LA4440 from Sanyo.It uses very less components other than the IC LA4440.A very high quality circuit with respect to its cost and ideal for beginners. Here IC LA 4440 is wired as a bridge amplifier to deliver a 19 W Rms on a 4 Ohm speaker. The IC has built in thermal, over voltage and short circuit protection.The IC also incorporates a audio muting function,but that is not used here. Notes . Use a 12 V DC power supply able to deliver at…

InfraRed (IR) Sensor/Detector Circuit Description. The circuit shows that the output of IC1 555 IC,which is designed for a duty cycle of 0.8mSec,with a frequency of 120Hz and 300 mA peak current, is used to drive the infra red LED,D1.From the connection it is clear that the diodes D1 and D2 are on the same line,just a few centimeters apart, on the breadboard.Thus diode D2 receives the infra-red output from the diode D1.The diode signal, which is given to the inverting terminal of the op-amp IC LM 358 gets amplified and its peak is detected by diode D4 and capacitor…