This circuit was found in Mullard's transistor application manual from 1960. More modern transistors can be used. The zener diodes used have the indicated voltages.
We found this circuit in the National Semiconductor Linear Applications Handbook of 1994. The...
This is 4-input audio mixer using an integrated circuit 741 and two more operational amplifiers....
This shield circuit for controlling the direction of rotation of DC motors with current up to 500...