This circuit uses uncommon Texas Instruments components today. The circuit is from an American documentation. Transistors are commonly used PNP. The display is 7 segment multiplexed.
This circuit is from an 1977 American publication. The coil consists of 30 + 70 turns of 28 AWG...
LEDs are diodes and can be tested with a simple configuration that allows the display of its...
This circuit using components that are still common in our market was found in a 1987...