Radio and communication circuits 1

This circuit represents a conventional Colpitts type crystal oscillator, where the output is taken from a low-value collector load resistor. Direct coupling is implemented into the base of a PNP transistor used as an amplifier, resulting in a simplified circuit...

Antennas for HAM transmitters

Antenna is the means by which a wireless operator puts his signal into the space and also through which he picks up the signals of the stations with which he wants to communicate. Hence after having a good Receiver and...

making an rf car

This article is authored by Yash Tambi, a Core Committee Member of roboVITics. It discusses RF-controlled robots, which are among the simplest types of robots. The essential components include a few readily available integrated circuits (ICs), a 433 MHz transmitter...

Tuned Rf Wavemeter

L1 and L2 form a tuned transformer with an optimum turns ratio of approximately 1:3. L2 and C1 are used to tune to the desired frequency. The frequency range can extend from 10 kHz to over 200 MHz, depending on...

handheld RF-Powermeter for multiple sensors up to 12 GHz

A few years ago, a diode-sensor based RF power meter was built using a 68HC11 microprocessor. Prior to that, an analog RF power meter with a thermal power sensor was developed. The datasheets for logarithmic amplifiers, which promised a measurement...

wireless temperature sensor

Here is the Arduino code for reading incoming packets from the XBee and displaying the received analog sample on the LED display. Parsing an XBee packet is complex, but it becomes manageable after studying the documentation. The code defines constants...

RF Remote Control Encoder and Decoder Chips Explained

Creating a universal remote control system has become quite straightforward. One can acquire the necessary chips, assemble them, and the high-tech remote control device will be operational. This document discusses specific remote control chips designed for this purpose. The IC...

Wireless Auto Tachometer

Anyone performing their own automobile tune-ups knows how important it is to know your engine's speed. With this tachometer, you can measure your engine's speed without any connections or annoying timing lights. The described tachometer is a non-invasive device designed for...

Wireless Telephone Line Spy

This is a phone bug circuit. This wireless telephone line spy circuit can be used to transmit the phone conversation to a nearby FM radio. This circuit must be... The phone bug circuit is designed to intercept and transmit audio signals...