View Full Version : Diodes and matrixes
In the Opencockpits forum these was a discussion on using diodes to stop ghosting or more than one switch being activated when only one is pressed in a switch matrix.
The diagrams I saw show putting the diode between the switch and the ground side. Many of my panels use a common ground for all the switches on that panel. Can the diode be used on the hot side of the circuit, if I reverse it? Or, will I have to rewire all of the panels?
737NUT
02-28-2008, 08:15 PM
Actually, i tried it the way it was shown in the other thread, i tried it like you said, and tried it on each switch. Nothing fixed it other than grounding the usb housing. OP support said diodes ar NOT needed on that usb axis card as the program in the pic has taken that unto account. Like i said before, i have no didodes and it is functioning PERFECT now after adding the gnd strap.
On my findings, diodes would be a waste of time to add when they are not needed. Another example in a real aircraft, the CDU keypad, it is matrix set-up and has no diodes!
I will try grounding first. Way I figure, you can't have too many grounds.
737NUT
02-28-2008, 10:28 PM
Let us know how works out for you.
Radar
02-29-2008, 12:51 PM
Actually, i tried it the way it was shown in the other thread, i tried it like you said, and tried it on each switch. Nothing fixed it other than grounding the usb housing. OP support said diodes ar NOT needed on that usb axis card as the program in the pic has taken that unto account. Like i said before, i have no didodes and it is functioning PERFECT now after adding the gnd strap.
On my findings, diodes would be a waste of time to add when they are not needed. Another example in a real aircraft, the CDU keypad, it is matrix set-up and has no diodes!
How did you do this. Connect a ground to the USB housing?
737NUT
02-29-2008, 06:03 PM
How did you do this. Connect a ground to the USB housing?
There are 2 solder lugs, one on each side of the housing where it is attached to the pcb. Use one of those.
Radar
02-29-2008, 06:29 PM
There are 2 solder lugs, one on each side of the housing where it is attached to the pcb. Use one of those.
Ok> Thanks:p
OK, I soldered a wire to the top of the USB connector housing and grounded it to one of the button grounds. No joy! I still get ghosting push one button and two or three will light up.
Just got through with a test flight in the Iris T-6II. The gear kept coming up and down on their own. LOL Something isn't right.
737NUT
03-01-2008, 01:37 AM
OK, I soldered a wire to the top of the USB connector housing and grounded it to one of the button grounds. No joy! I still get ghosting push one button and two or three will light up.
Just got through with a test flight in the Iris T-6II. The gear kept coming up and down on their own. LOL Something isn't right.
It doesn't go to the switch gnd. Try going to your pc case and then to what you have your switches mounted to.
Well, I got the switches working properly. But, it beats me how? I tried 737Nut's grounding. No joy.
I found that different switches needed to be hooked up different. With some, nothing. Others a diode on the ground side, still others the diode went on the switch side, and unbelievably others needed two diodes to work.
Why I don't know. But, I don't care, so long as they work.
The only ones I could not get to work were numbers 9-12 on my control stick. I have a single ground for all 12 switches and the card will allow me to only use eight of the switches. No matter, the other four are set to a second 4-way switch and I will try and hook them up to the OC master card, at a later date.
For now, I want to fly!!!
:)
737NUT
03-01-2008, 07:11 PM
Strange indeed! I wish i was an electrical engineer so i could figure it out! :) We made of Saitek's phantom button presses and now the USBAxis card does it