The circuit transistors, found in a 1974 documentation, may be the BC548. The circuit is used in quadriphonic systems to combine signals.
This circuit is suggested by National Semiconductor and makes use of the negative regulator LM2990...
This circuit was found in a 90s Radio Electronics. MOSFETs must have excellent heat sinks and heat and...
An oscillator slightly different from the previous one also appeared in Radio Electronics magazine in...