Voltage Level Detector (CB22135E)

We found this circuit in an English documentation from the 80's. Transistors are general-purpose types.

Voltage Controlled Current Source MC1536 (CB4496E)
This circuit was suggested by Motorola's 1993 Linear Interface ICs. Equivalent operational amplifiers...
10-Minute Timer (CB13950E)
This timer, from an old American publication, uses indicator lamps, but can be modified to use...
Subwoofer Filter (CIR25262E)
This low-pass circuit was found in the December 1990 issue of Radio Electronics magazine. The...