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SiriusHardware · 26th Apr 2018, 11:17 pm

I think the excess / unlimited anode current sourced by the 7408s is mitigated by the fact it's a multiplexed display, so each display cell is only actually 'on' for approximately 1/8th of the time, and not every segment of every cell is lit.

If you hold down the reset button on a working MK14 the display scanning is paused and you get a single very, very bright digit: Probably unwise to hold it in that state for long otherwise it might possibly cook the lit segments in that one display cell.

You appear to have your sources for 7408s and 7445s. Anything else missing?

Did you manage to find at least one pair of 2111 / AM9111 RAM ICs?

26th Apr 2018, 11:17 pm	#35
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: MK14 schematic revisions I think the excess / unlimited anode current sourced by the 7408s is mitigated by the fact it's a multiplexed display, so each display cell is only actually 'on' for approximately 1/8th of the time, and not every segment of every cell is lit. If you hold down the reset button on a working MK14 the display scanning is paused and you get a single very, very bright digit: Probably unwise to hold it in that state for long otherwise it might possibly cook the lit segments in that one display cell. You appear to have your sources for 7408s and 7445s. Anything else missing? Did you manage to find at least one pair of 2111 / AM9111 RAM ICs?