We found this circuit in a 2002 documentation. This die shows numbers 1 to 6 on a common anode display when the switches S1 and S2 are pressed. The circuit can be powered by voltages from 5 to 12 V.
The integrated circuit used in this project is not common today, but it can be implemented with more...
Found in an American publication from 1969, this circuit can be adapted to be used as a shield....
This current meter with many scales was found in a 80s American documentation. The operational amplifier...