Re: Tek 494AP VR board mystery

Ed Breya

If it is purely a (TTL) logic section, it could be that a little diode-logic was added to save a gate package or such, and required a little different biasing to assure proper levels. Often, a Ge or Schottky diode could be used with a saturated transistor output to get a valid TTL-low when isolation is needed, or a regular Si diode could work with some biasing help.


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