ƑƠɭįƠ is a simplistic, yet automatic outer foil tester for capacitors
Following some discussions about the subject, Outer foil cap measurement with Hantek 6022BE
Cap Foil Side Tester,
here is a small project based on the principles outlined here: Outer foil cap measurement with Hantek 6022BE
The process is rendered completely automatic: one just has to insert the cap to identify into the instrument, and a LED instantly indicates the foil side:
No more need for manipulations, comparisons or measurements.
The principle of operation is to send two antiphase waveforms to the CUT, and detect the polarity of the signal electrostatically leaked to the outside with a synchronous detector.
A single IC performs all the signal processing, and two transistor-based buffers handle the higher currents needed for large value caps (the instrument is designed for up to 4.7µF, but still gives usable indications with 10µF).
For fun and challenge, I built the whole thing into a small box of ear-plugs ("boules Quiès"):
The box is tiny, made of thin and soft PP (thus non-conducting, providing no shielding), and barely contains the circuit and 9V battery.
The power push-button is located underside: you just need to push on the box to operate the tester:
For large capacitors, the tester is equipped with an aluminum bracket and a phosphor-bronze strap, helped by an elastic band:
The smaller caps are handled thanks to a phosphor-bronze spring:
The construction is not especially tidy, but it works well:
The usefulness of such a gadget might seem questionable, but in fact a surprising proportion of capacitors are mismarked: more than 10%.
An example is the small yellow-block shown above: it is from the Philips/MBLE/RTC etc. group, not some dodgy Asian manufacturer
Following some discussions about the subject, Outer foil cap measurement with Hantek 6022BE
Cap Foil Side Tester,
here is a small project based on the principles outlined here: Outer foil cap measurement with Hantek 6022BE
The process is rendered completely automatic: one just has to insert the cap to identify into the instrument, and a LED instantly indicates the foil side:
No more need for manipulations, comparisons or measurements.
The principle of operation is to send two antiphase waveforms to the CUT, and detect the polarity of the signal electrostatically leaked to the outside with a synchronous detector.
A single IC performs all the signal processing, and two transistor-based buffers handle the higher currents needed for large value caps (the instrument is designed for up to 4.7µF, but still gives usable indications with 10µF).
For fun and challenge, I built the whole thing into a small box of ear-plugs ("boules Quiès"):
The box is tiny, made of thin and soft PP (thus non-conducting, providing no shielding), and barely contains the circuit and 9V battery.
The power push-button is located underside: you just need to push on the box to operate the tester:
For large capacitors, the tester is equipped with an aluminum bracket and a phosphor-bronze strap, helped by an elastic band:
The smaller caps are handled thanks to a phosphor-bronze spring:
The construction is not especially tidy, but it works well:
The usefulness of such a gadget might seem questionable, but in fact a surprising proportion of capacitors are mismarked: more than 10%.
An example is the small yellow-block shown above: it is from the Philips/MBLE/RTC etc. group, not some dodgy Asian manufacturer
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