Other settings like this can be found on this website. This makes use of old operational amplifiers, as the publication where we obtained, but equivalents can be used.
This circuit was originally designed for testing crystals used in color televisions, but it works...
This circuit was obtained in a General Electric documentation from the 80's, and can be used as a...
This small AM transmitter was found in a Japanese publication from the 1960s. The coil has 20 + 80...