Building off my first prototype, the same simple high impedance buffer amplifier with a transistor switch that illuminates a LED when the outer foil or shield of the capacitor is identified as driven by a variable square wave audio signal from ~60 to 2000 Hz. In addition, a DPDT switch was added to reverse the positive and negative oscillator source.
The schematic, BOM and parts layout are included in the first video at: • Prototype Build - Capa...
The buffer amplifier circuit is the same (with the exception of the near field or pickup coil - ref. video), while C1 in the oscillator circuit was changed to a 0.047uF capacitor and both potentiometers were changed to 250K.
Note: Separate 9V batteries were used to power the two circuits.
Enclosure:
www.amazon.com...
Spring loaded Binding Post:
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Hillman Spring Clip
Part no. 852987
Have fun and help improve this circuit by adding your tweaks or changes.
Best,
Don
Thanks for watching and subscribing to my channel on vintage radio repair.
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