UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Availability of TV valves for Nixie Clock.

julie_m · 10th Nov 2019, 12:41 pm

The 74141 is just logic gates configured to energise one output depending which specific combination of inputs is presented. And logic gates are just switches, so it's not an insurmountable problem.

For a display that changes once a second, you could just about get away with decoding the decimal digits using relays. To decode BCD, you would need up to five poles per binary digit. If you used twisted Johnson topology instead of BCD for your counters, you would need five flip-flops and relays per decimal digit (well, only three for the tens of minutes) but fewer poles on each (there are a lot of "don't care"s in the truth table).

10th Nov 2019, 12:41 pm	#24
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Availability of TV valves for Nixie Clock. The 74141 is just logic gates configured to energise one output depending which specific combination of inputs is presented. And logic gates are just switches, so it's not an insurmountable problem. For a display that changes once a second, you could just about get away with decoding the decimal digits using relays. To decode BCD, you would need up to five poles per binary digit. If you used twisted Johnson topology instead of BCD for your counters, you would need five flip-flops and relays per decimal digit (well, only three for the tens of minutes) but fewer poles on each (there are a lot of "don't care"s in the truth table). __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.