[sdiy] touch-sensitive switches - how?

Neil Harper metadata at gmx.com
Sun May 2 01:37:26 CEST 2021

so I had a chance to try some touch-sensitive stuff with the teensy LC,
and it's been pretty interesting. It all works great and as expected!
obviously i would need to program in the latching and do some sort of
hysteresis (like a schmitt trigger but in code :) thing so I don't get
any jumpy response.

interestingly, i had a better signal to noise ratio using the generic
arduino capacitance sense library than I did using the teensy's
dedicated "touch" pins with the appropriate commands. but both showed
really good results where I'll be able to do a simple "off" or "on"
thing very easily.

for a pad I just used a piece of copper tape. i also placed a second
piece about 1-2mm away and connected that to ground and was touching
between the two so my finger bridged the sensing pad and the grounding pad.

i was getting good signal just touching the sensing pad, but using the
grounding pad as well doubled the signal.

next i'd like to figure out what materials i might be able to cover the
bare copper with and still have the touch signal show up good. it'd be
great to not see bare copper but have some printed legend or color coding.

/// Neil Harper
/// Every Wave is New Until it Breaks

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