In Reply to: RE: Sherwood tuner posted by Eli Duttman on September 23, 2015 at 17:45:25:
Ely,For what it's worth, the LM1800 is what I refer to as a "first generation" multiplex decoder IC. There was a second generation that had better all-around specs - like lower THD and higher separation. I believe the Sanyo LA3361 was one but there were a few others - Hitachi and Rohm come to mind as manufacturers. I also remember that some were "pin for pin" compatible with the 1800. Have no idea what few if any of them may be found found today.
Circuitry was very simple compared to the discreet units and as your diagram shows - only one "simple" adjustment ("free running" 19Khz oscillator) is necessary - as the note indicates.
Charles
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- multiplex decoder chips - stellavox 14:06:55 09/24/15 (0)