Motorola suggests this circuit in an 80's documentation. The circuit uses an inverter to produce a higher voltage for 9 V battery charge from a single cell.
This 1965 Philips circuit uses old company transistors like the BFY51 and BFY50. The circuit is...
This circuit is from an April 1991 Radio Electronics magazine. The circuit uses power MOSFETs and...
This small power supply for low currents (5mA) is suitable for power low-power TTL experimental circuits....