Friday, 20 November 2015

Minitron [Numitron] 3015F Vintage Incandescent 7 Segment Display

I recently found these Minitron 3051F displays in some equipment i dismantled.

The Minitron is a 7 segment display with a decimal point that uses small incandescent filaments made from Tungsten to form the segments. They are an evolution of the Numitron which works on the same principal but are packaged in the old 'valve' style glass packages. The minitron is packaged in a more modern 16pin DIP form like LED based 7 segment displays but with a borosilicate glass cover. Note the decimal point is an 8th filament but is partially masked off.

Operating these is very simple, the recommended operating voltage is 5v with each filament drawing around 8mA at 5v so can easily be driven directly from microcontrollers (making sure your accounting for the cold resistance and resulting current spike when they first turn on). I measured the current draw at 5v with all the segments on (including the decimal point) and it totalled 67mA. They have a surprisingly long life of around 50,000 hours at 5v.