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Touch Sensors - three models

neilhart

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- Standalone Capacitive Touch Sensors - vender: www.adafruit.com

I found these sensors some time ago and first used them on my Mini-ITX Tower project. On that project I used the “Standalone Momentary Capacitive Touch Sensor” for the power on switch and the Standalone Toggle Capacitive Touch Sensor for the lamp switch.



Today I am using the “Standalone 5-Pad Capacitive Touch Sensor Breakout - AT42QT1070” and wiring up a control panel with a touch power on, a lamp on and a lamp off and a reset; this will use 4 of the 5 sensor circuits. And because I prefer to not add electronics to motherboards, I am using relays to isolate the touch sensors from the motherboard logic.

Here is the 5-pad unit on my desk. I have a copper penny as a pad taped to a .187 inch thick ABS plastic plate and my finger is being sensed through the plate as evidenced by the lit LED.



These units are reasonably priced and Adafruit usually ships same or next day. I use US Postal Service and the shipping cost is very reasonable.

Good modding,
neil
 
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- Standalone Capacitive Touch Sensors - vender: www.adafruit.com

I found these sensors some time ago and first used them on my Mini-ITX Tower project. On that project I used the “Standalone Momentary Capacitive Touch Sensor” for the power on switch and the Standalone Toggle Capacitive Touch Sensor for the lamp switch.



Today I am using the “Standalone 5-Pad Capacitive Touch Sensor Breakout - AT42QT1070” and wiring up a control panel with a touch power on, a lamp on and a lamp off and a reset; this will use 4 of the 5 sensor circuits. And because I prefer to not add electronics to motherboards, I am using relays to isolate the touch sensors from the motherboard logic.

Here is the 5-pad unit on my desk. I have a copper penny as a pad taped to a .187 inch thick ABS plastic plate and my finger is being sensed through the plate as evidenced by the lit LED.



These units are reasonably priced and Adafruit usually ships same or next day. I use US Postal Service and the shipping cost is very reasonable.

Good modding,
neil
Hi Neil,
I am thinking of trying one of these with a Cube mod and probably using a large area Copper shim as the contact to hopefully maximise sensing ability. I suspect though that the thickness of acrylic at the top of the Cube case might just be asking too much. How thick have you managed to go and still get a sensed touch Neil?
 

neilhart

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Hi Neil,
I am thinking of trying one of these with a Cube mod and probably using a large area Copper shim as the contact to hopefully maximise sensing ability. I suspect though that the thickness of acrylic at the top of the Cube case might just be asking too much. How thick have you managed to go and still get a sensed touch Neil?
minihack sorry for the late reply as I had not noticed your post.

It appears that these units calibrate at power on and seem to sense a touch at a fair distance.

On my current project, I had cut down the size of the pad to reduce the sensitivity for the reset switch and set the pad back into a hole. But then is ABS and not the cube acrylic.

Good modding,
neil
 
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Sorry to dig up an old thread, but I'm in the process of using the same adafruit sensor in my cube project. I haven't actually soldered or tested anything, but in my mind I'm not sure how this would work. Neil, how did you wire yours? I had thought initially if I just put the output of the PCB to the + terminal on my header that it would work, but the more I think about it, I'm not sure that will actually suffice.
 

neilhart

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Sorry to dig up an old thread, but I'm in the process of using the same adafruit sensor in my cube project. I haven't actually soldered or tested anything, but in my mind I'm not sure how this would work. Neil, how did you wire yours? I had thought initially if I just put the output of the PCB to the + terminal on my header that it would work, but the more I think about it, I'm not sure that will actually suffice.
When I add external electronics to my hack systems I use small 5 volt DC relays for isolation. In the case of Adafruit sensors, I have the sensor pulling up the relay, and the contacts of the relay wired to the motherboard front panel pins for the power switch.

Good modding,
neil
 
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Sorry, blew a PSU and got pretty busy at work for a week or so.

Neil, what you're saying is that you have the adafruit sensor just sending the signal to another relay- I assume in this case it's the momentary single-pad switch that sends an active high, correct? Has anyone done something similar with the active low send?

Incidentally, I still have the original sensor as well. Is it possible to add an external pad to that one by any chance?
 

neilhart

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Sorry, blew a PSU and got pretty busy at work for a week or so.

Neil, what you're saying is that you have the adafruit sensor just sending the signal to another relay- I assume in this case it's the momentary single-pad switch that sends an active high, correct? Has anyone done something similar with the active low send?

Incidentally, I still have the original sensor as well. Is it possible to add an external pad to that one by any chance?
Do a bench test of your original sensor and play around with it. I think that minihack has documented some alternate setups;

I am never comfortable with connecting my electronics to a motherboard directly, such as the power and reset switches as we do not know what the circuit is on each motherboard. So when I use an adafruit sensor, I rig the sensor to pull up a 5 volt relay and use the relay contacts to provide the function of a momentary switch.

Good modding,
neil
 
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Slightly related question for you (because you know a ton!!! :thumbup:) Wondering if you’ve had any dealings with a 2014 Mac mini and how this touch sensor would work out? I just picked one up and may put it into a cube case but I don’t know much about the mini’s power supply and how this switch would work draw power. I have yet to find any internal headers/pins to draw from. I’m not sure there is any standby power at all to any usb, etc.
 
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It's going to be a lot harder to try and rig that switch with an actual Mac motherboard, since Apple doesn't play by the standards rules that exist on most BYO motherboards. It's not to say it's impossible, but it's very impractical at the very least.
 
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