Here's the circuit I was using to simulate that. I'm pretty sure if they're too far out of phase, the receiver will choke up trying to demodulate the L-R channel.Īs the square wave can be busted apart into sine waves with Fourier analysis, my current design feeds a 38k crystal oscillator into a TTL frequency divider to get in-phase 38k and 19k square waves, then uses Sallen-Key lowpass filters with a high Q-factor (Q=10) and the cutoff frequencies set to the fundamentals to pull out the fundamental frequenies and block the harmonics. I'll need the 19kHz signal for the pilot tone and 38kHz signal for the DSBSC mixer.
FOUR TRANSISTOR FM STEREO MPX CIRCUIT HOW TO
The only thing I'm having trouble with is figuring out how to generate 19kHz and 38kHz phase-locked sine waves. Using this description, I've worked out how I'm going to implement most of the stereo multiplexer in analog hardware. Part of this entails design of a stereo multiplexer. 5) The FM MPX VCO uses laser locking making adjust ment and external components unnecessary. A separate oscillator circuit utilizes a 2N5210 transistor rather than a 38 kHz crystal that is often used, but not good. 3) Built-in reference voltage power supply provides good shortwave band frequency stability. All functions of this circuit are surrounded by a FM MPX signal.
Tune to a strong FM stereo station and note (and post). 2) DTS (both SD and IF count) compatible. Try this: Put a voltmeter between board terminal 3 (black meter lead) and terminal 4 (red meter lead). As a personal project, I'm designing a stereo FM transmitter from scratch. Features 1) Built-in AM monaural radio, FM IF amplifier/detector, and FM stereo demodulator.
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