Single Chip FM Transmitter Circuit SchematicA simple FM transmitter links your home-entertainment arrangement to a carriageable radio that can be agitated about the abode and into the aback yard. For example, you can comedy music on the CD banker in your active room, and acquire to it on a carriageable radio by the back-yard barbeque.
IC1 is a voltage-controlled oscillator with chip varactor. Its nominal abundance of cadence is set by inductor L1, and a 390nH amount places that abundance at 100MHz. Potentiometer R1 again lets you baddest a approach by affability over the FM bandage of 88MHz to 108MHz. Output ability is about -21dBm into 50 (most countries acquire emissions beneath 10dBm in the FM band).
The home system's larboard and appropriate audio signals are summed by R3 and R4, and attenuated by the (optional) potentiometer R2. R2's wiper arresting serves as a aggregate ascendancy by modulating the RF frequency. Signals aloft 60mV acquaint distortion, so the pot attenuates bottomward from that level.
In the absence of a accepted FM radio antenna, 75cm (30 inches) of wire will answer as a transmitting antenna. For best reception, it should be army alongside with the accepting antenna. The IC operates on a distinct accumulation voltage in the ambit 3V to 5V, but you should adapt the activated voltage to abbreviate abundance alluvion and noise.
IC1 is a voltage-controlled oscillator with chip varactor. Its nominal abundance of cadence is set by inductor L1, and a 390nH amount places that abundance at 100MHz. Potentiometer R1 again lets you baddest a approach by affability over the FM bandage of 88MHz to 108MHz. Output ability is about -21dBm into 50 (most countries acquire emissions beneath 10dBm in the FM band).
The home system's larboard and appropriate audio signals are summed by R3 and R4, and attenuated by the (optional) potentiometer R2. R2's wiper arresting serves as a aggregate ascendancy by modulating the RF frequency. Signals aloft 60mV acquaint distortion, so the pot attenuates bottomward from that level.
In the absence of a accepted FM radio antenna, 75cm (30 inches) of wire will answer as a transmitting antenna. For best reception, it should be army alongside with the accepting antenna. The IC operates on a distinct accumulation voltage in the ambit 3V to 5V, but you should adapt the activated voltage to abbreviate abundance alluvion and noise.
