This circuit works as a booster operating with signals from 1 to 30MHz. The gain is between 1 and 20dB. The circuit is from the 1990 edition of Radio Electronics Experimenter magazine.
This circuit appears elsewhere on this site, but from different sources. Using the LM3900, we find this...
This interesting source or isolation transformer also allows to vary the output voltage by...
In this circuit the CA3140, an operational amplifier, is used as a comparator with the zener diode...