7 Segment Display Encoder (with Diodes)

With this very simple technique, we can can generate all ASCII numeric characters and most ASCII alphabetical characters with a 7 segment LED display and with a minimum of components (1N4148 diodes) . This can be useful for example, for visualizing the position of a rotary switch, the selected input of an audio preamp, the current state of an electronic device, alarm etc. In most cases, a small number of characters are required which makes the circuit very simple.

Additionally, we can generate a large number of symbols.

For a single ASCII character, we don't need the diodes at all.