Author Topic: Capacitor Outside Foil Sniffer - "All In One Prototype"  (Read 252 times)

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Offline johnlsenchak

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Capacitor Outside Foil Sniffer - "All In One Prototype"
« on: August 08, 2019, 04:12:48 am »

The schematic, BOM and parts layout are included in the first video at:

Capacitor Outside Foil Sniffer - All In One Prototype
Published on Aug 7, 2019
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 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.

Posted   08/08/2019
John Senchak "Daytona  Beach  Florida "
 jls (at)

Offline David Hess

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Re: Capacitor Outside Foil Sniffer - "All In One Prototype"
« Reply #1 on: August 08, 2019, 09:48:27 pm »
That is clever but I just use an oscilloscope and my hand to determine which lead goes to the outside shield.

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