This circuit was found in an Electronics Now of the 80s applying to NiCad batteries of the time. The circuit is powered by a 12 VAC source, for example, the secondary of a transformer.
This 4.5 MHz amplifier is suitable for analog TV applications. We found it in a 1967 Philips...
This ultra-low noise amplifier and simple power supply was found in Analog Devices documentation from the...
Found in an RF Design from the 90's this circuit is intended for crystals of less than 1 MHz....