Sensors and Detectors

LDR change resistance when light fall on it. This is used in Light Detector Circuit using Wheatstone Bridge. One side of bridge has LDR and one fixed resistor in series. Other side has potentiometer and second fixed resistor in series. Voltage is given to two opposite corners of bridge. The output voltage taken from other […]

Simple Tilt Sensor Switch Circuit control ON/OFF of LED or buzzer. Tilt sensor work like small seesaw switch. Inside a sensor there can be a small metal ball. When sensor stand straight the ball touch two points and then the current can pass. When sensor tilts the ball move away and the current stops. This […]

Simple Missing Pulse Detector Circuit is an electric circuit. It finds when pulse is missing in pulse signal. Most time it uses 555 timer IC and work like monostable multivibrator. When it gets trigger it gives one output pulse. If next pulse does not come in time then timer is in no reset. Output pulse […]

LED turn on by LDR when dark. LDR and resistor connect in voltage divider circuit. In bright light transistor base get low voltage so transistor stay OFF. When dark come LDR resistance goes down and base voltage goes up with transistor turn ON and LED light up. This Simple Darkness Detector Circuit is easy to […]

This easy Motion Detector Circuit uses IC 555 to find human from far. Circuit have two parts: Transmitter: IC 555 work like astable multivibrator and it make square wave signal. This signal goes out through IR sensor (infrared). Receiver: Phototransistor see IR beam. If someone moves and block the beam then phototransistor work and turn […]