Found in an Elektor from the 90s, this circuit simulates a rotary switch that provides a BCD output from a 1 pole x 10 common position switch. The circuit can be powered by voltages from 3 to 15 V.
Two operational amplifiers are used in this source obtained in an American documentation...
This circuit is suggested by the Linear Applications Handbook of National Semiconductor, being used...
This simple circuit for headphones or small speakers was found in documentation from the 90s. The...