Bristol Digest, Vol 667, Issue 6

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Today's Topics:

1. Re: Capacitive switch test (Richard Stearn)

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Message: 1
Date: Thu, 27 Oct 2016 11:53:08 +0100
From: Richard Stearn <richard@rns-stearn.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Capacitive switch test
Message-ID: <5811DC94.50006@rns-stearn.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed

Steve Netting via Bristol wrote:
> I can't imagine how it works with only a single wire, unless the switch
> is also grounded via a metal case perhaps? There's probably a few ways
> it could operate but I believe a common method is to use an oscillator
> and check for added capacitance by timing the rise/fall time of the
> forward/trailing edge.
>
> Assuming it has a ground (even if via the case) and it's doing something
> similar to the above - I'd guess a small value ceramic capacitor between
> the wire and ground would be sufficient.

I have a couple of lamp units that go in plantpots and touching the plant
cycles the lamp from off to on and back. They work by detecting the (none
subtle) 50Hz pickup of the body touching the plant.

--
Regards
Richard

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End of Bristol Digest, Vol 667, Issue 6
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