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BH1417F FM stereo transmitter

A simple high efficiency FM stereo modulator electronic project can be designed using various electronic circuits . This stereo FM stereo modulator circuit use the BH1417F FM stereo transmitter IC which consists of a stereo modulator for generating stereo composite signals and a FM transmitter for broadcasting a FM signal on the air. The stereo modulator generates a composite signal which consists of the MAIN, SUB, and pilot signal from a 38kHz oscillator.
The BH1417F FM transmitter radiates FM wave on the air by modulating the carrier signal with a composite signal.
This BH1417F stereo FM transmitter is capable of broadcasting good quality signals over a range of about 20 meters and is ideal for broadcasting music from a CD player or from any other signal source so that it can be picked up in another location.
This BH1417F stereo micrometer broadcasts on the FM band (ie, 88-108MHz) so that its signal can be received on any standard FM tuner or portable radio.

L1 coil comprises 2.5 turns of 0.5 - 1mm enamelled copper wire (ECW) wound onto a tapped coil former fitted with an F29 ferrite slug. Alternatively, you may also use any commercially made 2.5 turns variable coil.
The antenna for this micrometer circuit project consists of a 1.5m length of insulated hookup wire, with one end soldered to the antenna terminal.
S 1 , S2,S3,S4 switch is a SPDT subminiature switch (Jaycar ST-0300, Altronics S 1415 or equiv.) and is used for frequency selection .
Using the table bellow you can configure the transmitter frequency .
BH1417F FM modulator frequency selection.jpg
VR1 and VR2 must each be set to the same position, to maintain the left and right channel balance .

This stereo FM micrometer must be powered from a power supply that will provide an output voltage between 9 and 12 volts or a 6 volts battery .
If you want to use a 5 volt DC voltage to power this circuit you need to remove the D1 , ZD1 diodes and the 7805 linear regulator .

BH1417F FM modulator circuit schematic


The circuit shows a capacitor (Cp) to gnd at the pilot signal adjust pin (19). What value is recommended for this capacitor? Merlin

Usually is 470pF(picofarads)

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