This 2.5 A power supply was found in a 90's QST magazine. The power transistor must be mounted on a heatsink.
This circuit, from a 1973 documentation, can be made with BC549 transistors. The frequency depends on...
Found in a Philips documentation from the 90s, this circuit uses transistors from that time....
This circuit has a logarithmic response sourcing signals to na analog meter. The meter is a 200 µA or...