Bug Detector

This simple infrared (IR) detector activates a red LED when the transistor Q2 is exposed to invisible IR radiation, commonly found in fiber-optic systems, position sensors, and TV remote-control units. The device can be constructed using a 9V battery...

A PIN photodiode, four low-noise operational amplifiers, and a comparator are utilized to detect individual photons of gamma radiation. The schematic, design considerations, and component selection are discussed. The circuit design incorporates a PIN photodiode, which is a semiconductor device...

Men often appreciate the convenience of television remote controls, which can sometimes frustrate their female partners. They tend to switch channels frequently, wanting to ensure they do not miss anything while a specific program is on. With the remote...

This circuit de-energizes a normally energized relay if the input voltage exceeds or falls below two individually set voltages. The transistor driving the relay is typically activated by resistor R4, keeping the relay energized. If the cathode of diodes...

This circuit is a motion detection sensor that utilizes a light source and detector as an infrared motion detector. The motion sensor employs an infrared LED and a phototransistor. Since it relies on light, the sensor's sensitivity can be...

The circuit incorporates two oscillators, both operating at about 40kHz. The first, IC1a, is a standard CMOS oscillator with its frequency adjustable via VR1. The frequency of the second, IC1b, is highly dependent on the inductance of coil L1,...