PC touch sensitive power switch with led reactive light

Thread Starter

saltynay

Joined Jan 19, 2020
5
Hi,

I am doing quite a lot of heavy modifications to my PC case, and I am stuck on an issue involving a Capacitive Anti-Vandal Momentary switch (CS4M2FR information) as I have next to no electronic experience. I want to wire the switch in parallel to the current switch so that I can use it as an alternative switch located on the top of the case which is an easier to reach location then behind the lockable front panel door.

Through trial and error I have worked out I need to connect the ground (Black) to the negative pin for the power switch, the NPN (Brown) to the positive pin for the power switch and the 5-24VDC to the positive pin for the reset switch. On page 4 linked here of the switch data sheet. It details an example use case that is directly applicable to what I require however my limited electrical knowledge means I can't decipher it.



If I ground one of the colour led wires against a metal panel then that corresponding led lights up constantly regardless of whether the switch is in an off or on state. If I connect a colour led wire to the negative pin for the power LED then it lights when the system is off and turns off when the system is on (the reverse of what I want).

Thank you in advance to any help you can offer.
 
Last edited:

pmd34

Joined Feb 22, 2014
503
The datasheet diagram for your switch shows that you have to connect the coloured wire to GND to switch on the LED, (independently of what the switch is doing, so long as there is power to it.) So the case of your PC will always be grounded hence the LED lights all the time.. For the PC connections, you would need to check with a multimeter what voltages are actually being sourced. For example the "Power LED" it is normal to switch off and on the (+) signal but have the (-) supplied all the time.

So you might have to have an additional transistor or relay to invert the signal to switch on your button LED. Though you might find the (-) connection on the USB is switched off and on with the power.
 

Thread Starter

saltynay

Joined Jan 19, 2020
5
For the PC connections, you would need to check with a multimeter what voltages are actually being sourced. For example the "Power LED" it is normal to switch off and on the (+) signal but have the (-) supplied all the time.
Pins 3,4,5,6,7 and 8 on the JFP1 connector are supplied at all times and provide 5v on the (+) side.

So you might have to have an additional transistor or relay to invert the signal to switch on your button LED. Though you might find the (-) connection on the USB is switched off and on with the power.
Excellent idea with the USB header there is an internal LED 5v strip header just above the power connectors that may provide that functionality. It is labelled as JRAINBOW on pg 41 of the motherboard manual would this work and how could I test just trial and error?
 

pmd34

Joined Feb 22, 2014
503
I guess you could connect a multimeter to the JFP1 (+) 5V pin and the the other lead to (-) of the USB and see if it switches off and on.. though there is a good chance that the PC will only switch the positive supply.
 

Thread Starter

saltynay

Joined Jan 19, 2020
5
I guess you could connect a multimeter to the JFP1 (+) 5V pin and the the other lead to (-) of the USB and see if it switches off and on.. though there is a good chance that the PC will only switch the positive supply.
I tried attaching a regular momentary switch to pin 6 on the JFP1 pin connector and pin 4 (Ground) on the JRAINBOW connector and the switch turned off and an on the PC as normal. I will try with a USB header now.
 

Thread Starter

saltynay

Joined Jan 19, 2020
5
I tried attaching a regular momentary switch to pin 6 on the JFP1 pin connector and pin 4 (Ground) on the JRAINBOW connector and the switch turned off and an on the PC as normal. I will try with a USB header now.
No luck with USB headers either tried both USB2 and USB3 connections and ground is always connected. I am not sure if this is useful but on JFP2 connector the ground terminals are active when the PC is off but deactivated when the PC is on.
 

Thread Starter

saltynay

Joined Jan 19, 2020
5
So after a lot of trial and error and the help of both pmd34 above and a makerforums.info user. I have come up with the following circuit map. I had to find a constant 5V power supply to connect to the power cable for the CS4F2MR and that involved finding a header that wasn't listed in the motherboard manual but was present on the board. After I had done that it all fell in to place.
Pin Map.jpg
Now to wire it up and see if it works in parallel to the current switch to allow for two switches.
 
Top