This power source was found in a 1968 Electronics World. The transistors are from that time. The current of each output is limited by the transformer.
This circuit was found in an old documentation and can be implemented with BC549 transistors. The...
This mid-waveband receiver was found in a book on transistors from 1954. The antenna coil is of...
Old multimeters used a 22.5 V battery for high resistance measurements. If you have one, you...