This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
For the 1 MHz frequency, the pass band of this filter is only 120 Hz wide. The filter is suitable for...
Found in a 1974 Ferranti manual, this circuit uses diodes to limit the voltage on the transistors. The...
Found in a 90s Electronic Design this circuit provides an additional 12 V output to a 5 V...