Free Space Optical Communication circuit

This device was originally designed to test the Shutter Time Meter, which is specifically intended for analog SLR cameras. To accurately measure a camera's exposure time, it must first be checked with a well-defined signal. This circuit serves that purpose...

Low Power Wireless Audio Power Amplifier as baby mointor

This appears to be an infrared (IR) transmitter. IR signals do not penetrate walls, and it is assumed that this device is intended for use in a room separate from the one in which the user is located, rendering it...

Noisy Regen Receiver

The following circuit illustrates a Noisy Regenerative Receiver Circuit Diagram. Features include a Noisy Regenerative Receiver Circuit, which simplifies the process of... The Noisy Regenerative Receiver Circuit is designed to amplify weak radio frequency signals while also incorporating a regenerative feedback...

6-17 MHz SW reciever

Its very simple as It uses only 3 transistors 2n2222. The Coils can be altered to change the range of reception by lowering or highering the frequency. More: This circuit is a SW band receiver of range 6 to 17...

wireless telephone line spy circuit

This design outlines a phone bug circuit. The wireless telephone line spy circuit is capable of transmitting phone conversations to a nearby FM radio. The circuit must be connected to a standard phone line. In the circuit, the first transistor...

Laser-Guided Door Opener

This automatic door opener can be constructed using readily available components. The electromagnetic relay at the output of this device can be utilized to control the door mechanism. The automatic door opener circuit is designed to facilitate the opening of a...

Receiver/Scanner Preamp Circuit

The low-cost Mini-Circuits MAR-X series of chips provides a significant advantage for RF builders, featuring inherent 50-ohm input and output impedances essential for RF systems. An MAR-1-based receiver/scanner preamplifier is illustrated. Capacitors Ci and C2 are chip capacitors, with values...

Small Radio Transmitters

Information about building a small radio transmitter, which has a PCB measuring 1.75" x 2.5" (45mm x 68mm) and has a range of approximately 30 yards. The documentation states that the frequency range is 100-108 MHz, but it has been...

Laser Door Alarm Circuit

This laser door alarm operates by detecting the interruption of a laser beam. A low-cost laser pointer serves as the light source. When an individual crosses the path of the laser beam, it triggers the alarm. The laser door alarm circuit...