The FM transmitter circuit includes RDS/SCA input and Audio/MPX input with optional preemphasis. This PLL transmitter can be used with or without stereo encoder. Tuning range over the FM band is provided by two buttons that control dual-speed PLL. The transmitter can work also without the LCD display. Read more »

This FM transmitter circuit is PLL controlled and still very easy to build. Frequency is set with 4 buttons and a LCD display show you the frequency. Print your own display text on first line. The smallest step size is 50kHz and the transmitter will work from 88 to 108 MHz. Read more »

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 »

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 »

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 »

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. Read more »

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 »

This transmitter project will show you how to build a mini broadcasting device that can transmit an audio signal up to a quarter mile to any FM receiver. It’s easy to build and a good learning experience and best of all – it’s free! Read more »