Filament source (T398E)

Despite being transistorized, this is a constant current source circuit for 1 V valve filaments such as the 1H4 tube.

RIAA Equalizing Preamplifier (CB4947E)
Indicated for vinyl media recovery, this circuit is from the 80's, having been found in an...
Magnetic Levitation Circuit (CB23792E)
This levitation circuit keeps a small globe floating in space under the action of a magnetic...
Frequency-Corrected Astable (CB25651E)
This frequency-corrected 1 kHz circuit has a nearly perfect rectangular signal. The circuit is...