Found in a 1965 Radio Shack documentation this oscillator can be used with modern general purpose transistors like the BC558. The transformer is the output type for transistor radios.
The cut-off frequency of the filter shown in the figure can be adjusted to values between...
This circuit was found in a Popular Electronics from the 90s. The components used are all common...
This circuit uses a dual floodgate MOSFET not very easy to obtain today. Its handling is very...