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.
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
This circuit was found in a 1970s documentation. The integrated circuit used is uncommon today....
This filter was found in Exar documentation from the 1980s. The circuit has an attenuation of 60 dB at the...