/diy/ - Do It Yourself

>>1413791
Ah, that's not too bad an idea for a project. Don't want a neutral/out-of-gear indicator? Also making an R look not like an A means you'll need something other than a 7-segment display. A 14- or 16-segment display (pretty common) would work though, and it would only add another transistor or three to the works compared to just using a 7-segment A instead.

To do it with ICs the best way would be to use a 1-of-16 decoder, a hexadecimal-to-7-segment decoder (MC14495P1), and a few peripheral transistors to use the first reed switch to display an F but add the extra two segments to show an R. You'd also need to use discrete transistors to drive the LED display since the split segment(s) will draw twice the current as the single segment it would be expecting. Unless you want to cheese it and use a microcontroller.

Pic related is the semi-compact truth table for doing it in discrete transistor logic, but expanding out the "x"s is proving a right pain I'm not even going to attempt a karnaugh map.

>>1413812
>7 transistors
Sure maybe with a nixie tube, not with a 7+ segment.