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BH1417 pll stereo transmitter circuit schematic

BH1417 Stereo PLL FM Transmitter Circuit

This BH1417 pll fm transmitter includes features like: pre-emphasis, sound limiter, stereo transmission, low pass filter, pll circuit, fm oscillator and rf output buffer. The sound limiter maintains the same audio level so no distorsions occur, the stereo encoder separates the left and right channel enabling stereo transmission, the low pass filter blocks any audio signal above 15 Khz to prevent rf interference and the pll circuit provides a rock solid frequency stability.

There are 14 possible transmission frequencies with 200KHz increments selected with a 4-DIP switch. Starts from 88.7 up to 89.9 MHz and 107.7 up to 108.9 MHz.

S4
S3
S2
S1
Frequency
1
1
1
1
88.7 MHz
1
1
1
0
88.9 MHz
1
1
0
1
89.1 MHz
1
1
0
0
89.3 MHz
1
0
1
1
89.5 MHz
1
0
1
0
89.7 MHz
1
0
0
1
89.9 MHz
1 = ON, 0 = OFF

Simply select transmission frequency at which you would like to transmit, set the combination for 4-DIP switch and BH1417 will tune to that frequency. If you can’t hear the transmitted audio signal on your FM receiver then re-adjust 2.5 turn variable coil until you can hear the signal.

BH1417 transmitter pcb

Technical Specifications
Supply Voltage: 4 – 6V
Transmission Frequency: 87.7 – 88.9MHz, 106.7 – 107.9MHz (200kHz steps)
Output RF Power: 20mW
Audio Frequency: 20 – 15KHz
Separation: 40dB
Power Consumption: 30mA

Components

1x BH1417 – Stereo PLL Transmitter IC (Case SOP22)
1x 7.68 MHz Crystal
1x MPSA13 – NPN Darlington Transistor
1x 2.5 Turns Variable Coil
1x MV2109 – Varicap Diode
1x 4-DIP Switch
ANT – 30 cm of copper wire

1x 22K Resistor
7x 10K Resistor
1x 5.1K Resistor
2x 3.3K Resistor
1x 100 Ohm Resistor 1x 100uF Capacitor
3x 10uF Capacitor
2x 1uF Capacitor

1x 47nF Capacitor
3x 2.2nF Capacitor
1x 1nF Capacitor
1x 330pF Capacitor
2x 150pF Capacitor
1x 33pF Capacitor
2x 27pF Capacitor
1x 22pF Capacitor
2x 10pF Capacitor

BH1417 Stereo pll transmitter circuit diagram

BH1417 pll stereo transmitter circuit schematic

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