This is an interesting one – these devices are tiny touch-sensitive buttons – handy for lots of projects – I’ve been working on this for a while (and not getting far until now). These buttons have been around for a while – we used them in our thermostat project AGES ago – but recently when trying to buy some, I hit across a problem that while AliExpress had them for sale very cheaply, they came with no information and mine arrived, programmed to toggle state (and light output) every time they were touched – NOT whan I wanted. I need simple touch to light-up/turn-on, release to extinguish/turn-off.
Then I checked on the BANGGOOD site and the same thing (so it appeared) was a lot more expensive than AliExpress. So now I have my first sample from Banggood – and while still not as cheap as AliExpress – I’m more impressed with the fact that the Banggood version has a link shorting option to change from toggle mode to momentary mode without which I could not make use of these handy devices. I did mention the original versions of these buttons on this blog entry if you’re interested,
Take a look at the composite photo (top of the page). On the left two images you see the button from Banggood when attached to 3v3 and touched. By default you would touch them again to turn off (in this case) the RED light. NOT what I would want. In the centre photo you will see a pair of solder pads on the back (the connector has OUT, GND and VCC in that order). By soldering the two pads together, the default behaviour is changed to momentary operation – which is what I want.
Over on the extreme right above (top composite image), you’ll see the AliExpress version of these buttons – it is not at ALL obvious how to change that default behaviour. The single solder pad must be there for a reason but what do you short it to, if anything. Reader XANDER in the comments below points to a resistor on the AliExpress versions which when removed changes the behaviour of the button like the link in the Banggood version. I just tested the AliExpress version – with the resistor he highlighted missing, it changes to normally unlit, momentary touch mode.
Still doesn’t explain the purpose of that lone soldered pad if anyone is feeling experimental. As REMOVING a resistor sets the Ali board to the opposite of the Banggood version I’m even more interested in what would happen if that spare pad was connected to one of the other two pads (where the resistor was) via a 1K resistor (can’t be that hard to try). Ok, I tried, made no difference.
For some reason it sticks out in my head that the very first buttons I used some time ago had link options for latching or momentary – and also active high or low.
When I say touch-sensitive – they will even work through very thin plastic – so that in our original thermostat project – we had a plastic front back-painted in black except for triangular areas for up and down buttons – using this style of button. The limit is mainly down to imagination.
You can get these buttons in a variety of colour options, red, green, blue etc. Banggod still need to work on that price but at least I can easily use these.