TTP223 Erratic Behavior

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eTech said:
Maybe what you ordered is already there?
Click to expand...
if they are they are invisible.
Now i ran into this a bit ago today. Looks like that schematic goes with this module. Mystery solved?
 

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eTech said:
C1/C2 should be added if they don't exist.
Click to expand...
i did add both caps (10uf & 0.1uf) to the circuit
i placed them across pins 1 & 2 of the sonrom module.
-CORRECTION VCC & GND-
i then removed the pigtail connector from the module and attached the module directly to my board. (as it was initially)
the behavior was unchanged. after i turn it on it will (without interaction) cycle on and off repeatedly after about a miniute of being on. im unable to stop it.
i replaced the pigtails and the erratic behavior stopped.
Now it does turn back on by itself ONLY after i turn it off. As i continue to touch to turn it off it will come back on. i can stop this behavior by holding my finger on the button for 2-3 seconds. i leave it powered up for 10 minutes and it does not turn back on by itself.
I do not have a 30pf cap for the pads sensitivity. it is on order. the smallest i have is 100pf
Regardless of the outcome i appreciate the time. i have learned a great deal. Thank you eTech.
 
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i have updated my other project to include both caps. When the 30pf cap arrives ill add it to the project with a jumper.
 
Board looks good.

Keep in mind that the 30pf cap may need to change to a larger (less than 50pf) or smaller value depending on test results.
 
eTech said:
Keep in mind that the 30pf cap may need to change
Click to expand...
what do you think of using this. maybe in series with a 10pf cap
Specifications
Capacitance Min:6pF
Capacitance Max: 30pF
Voltage Rating: 100V
Series: 6mm Lead Type
 

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Note:

capacitors in parallel add

capacitors in series use the 1/Ct=1/C1+1/C2+...1/Cn rule

Just the opposite for resistors.
 
Sorry if im being a bit of a pest but the store i order from is out of the SMD version of 10uf cap. Is there an issue if i use the lead style?
Specifications
Multilayer- Monolithic Ceramic Capacitor
Capacitance: 10uF
Voltage-Rated: 50V
 
a better question is should i use a trimmer cap?
i understand that just because it is a capacitor it may not be practical in this circuit.
im just not able to get the range of fixed caps i need and looking for an alternative.
the aussie in this video has suggested i connect this in a particular way (adjusting pin to ground) so when i adjust it the metal screwdriver does not interfere with it.
 
ThomsCircuit said:
adjusting pin to ground) so when i adjust it the metal screwdriver does not interfere with it.
Click to expand...

There are plastic alignment tools. Essentially hex and slotted screwdrivers. Hex and slotted were used in variable inductors. You had screws on variable capacitors used for radio tuning for adjustments.

Fixed is always better.
 

The problem with any "mechanically variable" part is they can become "de-tuned" over time due to temperature, vibration, etc.
So, as stated in #35, fixed is always better.
 
eTech said:
The signal source is the Touch pad, so I'd move the 30pf cap over next to the header pin labeled "PAD" and connect it there.
What is C6 (next to Jumper B)?

BTW- Keep the wire twisted together from the TP to the PCB.
Click to expand...
Moving c5 (10-30pf) over to PAD IN. your so right about that. Good catch.
C6 is (was) going to be the Var Cap (4-40pf)
I've been told its better to use fixed so thats out now.
My next Q. Can I use mono lead type caps? I can get them 10,20,30,40pf. (Like in the photo #31) the SMD versions are not available in the sizes I need. Thank you.
 

Yes. Totally up to you. Radial, Ceramic would be good, like MLC or X7R type caps. The ones in the photo #31 look good.
 
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