With an 18 V input, this regulator was found in Philips documentation from the 60's. The transistors are from that time. The power transistor must have a heatsink.
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...