This circuit for light modulated in frequency (FM) was found in documentation of the 90s. SUS is uncommon today, but transistors admit equivalents.
This filter with the 741 op amp was found in the February 1995 Electronics Now magazine. The power...
Found in an American documentation from the 90s, this circuit makes use of an output transformer for...
This directed coupled amplifier uses a transformer to drive a low impedance loudspeaker. This...