This circuit was found in an Elektor from the 90s. It makes use of digital CMOS integrated devices common today. The signal is controlled automatically sequentially.
This transistor source has the output voltage selected by zeners and the LED indication of which...
This filter can use almost any common operational amplifier and needs a symmetrical power source. The...
This receiver, called Peace, was manufactured in the 1960s in Japan and was powered by a 9 V...