6AC7 Amplifier (T450E)

Obtained in MIT documentation, this 4-stage circuit has high gain for small signals. The power supply sources 150 V.

Successive Tone Decoder PLL (CB3958E)
This circuit with the known PLL 567 can be found in other versions in this section and in this...
Heart Rate Indicator (CB5013E)
I found this circuit on a December 1976 Radio Elettronica. The Italian magazine no longer exists, but...
SVPK Conductive Polymer Capacitors
May 2017 - The new series of new polymer conductive capacitors from Panasonic OS-COM is already in...