Explorer for all ranges (T1098E)

This circuit was found in a Radio Craft from October 1946. Power supply not shown, and tubes are 1.5V filament types.

48 V to 15 V step down converter with 1.5 A (CB1572E)
To operate with high input voltages using a 3-terminal voltage regulator such as the LM340-15, we...
1 Hz to 12 Frequency Doubler (CB13739E)
This circuit was found in an American magazine in 1976. It doubles the frequency of TTL signals in the...
Load disconnect switch (CB8517E)
Found in a 90s Maxim documentation, this circuit disconnects the battery in case of overload. The...