Archive for November, 2009

FM Transmitter for Telephone Broadcaster

This is a simple FM transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet. It is extremely easy to build and is therefore a good, useful beginner project. Read more…

FM Transmitter with LCD Display-8W

This is a nice PLL FM transmitter with LCD display, PLL generated by TSA5511 I2C synthesizer controlled by PIC16F84 microcontroller. Output fequency can adjust from 88 to 108 MHz with 50 KHz steps. Read more…

Linear Power Supply 13.8V 20A

A linear power supply has a transformer that steps down the line voltage to some voltage, a rectifier and a filter capacitor transform the low voltage AC into a moderately filtered DC that still is unregulated and has some ripple. Finally, a regulating circuit “burns off” the excess voltage, leaving only the exact amount desired at the output, typically 13.8V for communication equipment. Read more…

Free RF Simulation Software-RFSIM99

RFSim99 is a free RF Simulation software that can help you  in your RF Projects, especially if you are trying to design radio filters. RFSim99 works with S-parameters.

This means that not only will it simulate and analyse circuits built out of its internal library of components, but that it can accommodate any circuit block or stage for which these are known. Read more…

Elliptical RF Low-pass Filter-Reflectometer

Here’s a schematic reference for building Elliptical (Cauer) RF Low-pass Filter for FM Amplifier 88-108 MHz. A ninth-order, elliptic, low-pass filter attenuates harmonics generated in the power amplifier. The capacitors for the filter are circuit board pads. Read more…