We found this circuit in a 1964 Electronic Design. It provides 0.5 V signals from 4 kHz subcarriers. Transistors are from the era.
This circuit with power MOSFETs was found in a 1980s Siliconix documentation. Equivalent MOSFETs...
This 80's General Electric circuit is guarded by the noise-guard for operating current. The...
This circuit was obtained in a 1964 Electronic Design. The components used are from that time....