Re: HP 312A wave analyser
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What about the 7441/74LS41 BCD to decimal decoder designed to drive Nixies?
I have a 312B, which uses LED displays, with a much simpler counter design.which uses the 74LS75 Latch and the 74L47 BCD to seven segment decoders. The 312A manual that I have is so speckled tht I can't read it to determine the logic levels.
On Thu, Mar 16, 2023 at 12:57?PM Greg Muir via <big_sky_explorer= [email protected]> wrote: Brad,
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If I can recall the neon-photocell approach was very similar to that used in the HP 5245L counter series display boards.? If you can find an old board (base P/N 05212-6016) you might have some luck in finding similar photocell devices.? The suffix to the part number (¡°Series 6xx¡±) changed reflecting the board functionality.? There was also changes in the design of these boards where they either contained an enclosed module termed ¡°Decoder¡± (One HP part number is 1820-1683¡±)? or a ¡°Photoconductor Plate¡± where the photocells directly drive the Nixie tubes.
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It appears that HP changed to the ¡°Decoder¡± module in later model counters.? It is a black plastic enclosure on the board with a removable cover but I have never opened one up to see what is inside.? Given its construction I am assuming that it, too contains photocells.
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Greg
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Michael A. Terrell