In this case, the end product is a binary-to-seven-segment decoder built from scratch. In engineering circles, this circuit is better known as a 7447 BCD to seven-segment decoder/driver ...

[Fran] demonstrates the display running with a CD4511B BCD-to-7-segment decoder, hooked up with a bunch of 3904 power transistors to get the chip working with filament bulbs instead of LEDs.

In fact, any other combination of seven segments not available to seven-segment decoder-type drivers can ... of the logic 1 low time. With the circuit shown, the logic 1 low time should be between ...