Circuit Diagram


Unity Gain Follower by IC LM741

This is the Voltage Follower used to transfer or copy a voltage from a first circuit (Vin) to a second circuit (V out),with gain rate is equal to 1 only, that is AV = Vout/Vin = 1 ; Vout = Vin. The input has high impedance, and the output is low impedance. It prevents the […]


Transistor intercom circuit.

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 […]


Telephone off-hook indicator

Description. The circuit depicted here can be used as an indicator when the telephone receiver is off-hook. The circuit can be in corporated with old telephones that does not have such an indicator. The circuit uses a complementary darling to pair using Q1 (2N3904)and Q2 (2n3906) to sense whether the receiver is off hook and […]


Simple Lamp Dimmer/ Fan Regulator

A Lamp Dimmer/Fan Regulator Circuit We have modified this circuit: – Take a look – Modified Lamp Dimmer Description . This is the circuit diagram of the simplest lamp dimmer or fan regulator.The circuit is based on the principle of power control using a Triac.The circuit works by varying the firing angle of the Triac […]


Plant moisture level monitor

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 […]


Mosquito repeller power saver

Description. Almost all liquidator type mosquito repellers are rated 5Watts. It is a pretty energy consuming game when these repellers are operated through out the night. Even though these liquidators are switched ON and OFF in discrete intervals there will be no considerable loss in the effectiveness, and more over there will be a great […]


Mobile incoming call indicator

Description. This circuit can be used to escape from the nuisance of mobile phone rings when you are at home. This circuit will give a visual indication if placed near a mobile phone even if the ringer is deactivated. When a call is coming to the mobile phone, the transmitter inside it becomes activated. The […]


Simple Water Level Indicator Diagram

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 […]


Simple Relay Circuit

The following schematic illustrates the Simple Relay Circuit Diagram. When the switch S is closed in a relay circuit, current flows in the coil, causing a strong magnetic field around the coil. The soft iron bar in the lamp circuit is attracted toward the right end of the electromagnet and makes contact with the conductor […]


Touch Switch 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 […]