Sonoff basic with touch switch problem

[Genesys]

btw what touch sensors did you order . I have tried both the red ttp223 and the blue ttp223 boards . The blue i couldnt get to work correctly even on the breadboard .The only way i could get it to turn on is by directly putting my finger on the TTP223 chip itself.

[Shardan]

Hello Genesys,

These sensors do not work on contact but by capacity.
Even if you touch the sensor itself you usually won't get in electrical contact,
there is a lacquer coat on the copper.
Your finger and the sensor build a capacitor, small but big enough to trigger the sensor chip.
I don't know the dielectric constant of PLA, it might be good enough to make the sensor work even through the PLA.
Pure PLA is classified as "Isolating" if i remember right. That says it has around 10^12 Ohm.
But there are variants that are classified "AntiStatic" or "conductive", says they have a lower resistance.

I've ordered samples of several types as they are a dime a dozen:
https://www.aerial.net/shop/imageslarge ... 23_top.jpg
http://img.dxcdn.com/productimages/sku_434360_1.jpg
https://4.imimg.com/data4/PM/EH/MY-1833 ... 00x500.jpg
Anyways it will take a while due to the well known hyperspeed of chinese snailmail
If i get some i'll take one of my sonoffs and check.

Due to the datasheet you should not remove the ceramic capacitor, use the biggest possible (50pF) instead:
The value of Cs use smaller, then the sensitivity will be better. The sensitivity adjustment must
according to the practical application on PCB. The range of Cs value is 0~50pF.

Datasheet: http://www.tontek.com.tw/download.asp?sn=475
(Always fun to read english from chinese translators )

Regards
Shardan

[Genesys]

Would changing the sensitivity help any? Right now i can get it to turn on with my finger about 6mm off of the board . Theres only one capacitor that comes on the board which i probed to be a 90nf ceramic cap and its the C1 cap as per datasheet between VCC and GND . The board does not come with a cap on the sense pin. Shouldnt there be a cap on the sense pin with a value between 0 - 50pf as per the datasheet? Im guessing they just dont put a cap(0 value) so the sensor is at max sensitiviy . Could adding a 50pf NPO ceramic cap off the sense pin help my problem?

The blue boards are different from the red boards . The blue board doesnt have a C1 cap at all and come with a 50pf cap off the sense pad pin .

[Shardan]

Hello,

the pictures a Google and AliExpress show some differences, maybe soe not... that's why i ordered several different ones ( and hope i'll get the same with the enxt order )

Just give a 50pf at the sensing pad a try. Worst that might happen is it stops working and you have to remove it. 6mm seems very sensitive to me.

Regards
Shardan

[MaleBuffy]

Hello,

have you made it work with AC to DC power?