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.

Darlington touch switch (CB9564E)
Any high-gain Darlington transistor can be used on this touch circuit. The load can be formed by...
15W Inverter (CB25380E)
This circuit is from an April 1991 Radio Electronics magazine. The circuit uses power MOSFETs and...
Low Pass Filter CIR13599S (CB6243E)
We found this circuit in a 1980s Linear Technology documentation. The components are from the...