In a matrix, if you press one switch you stand the chance of back feeding a second or more switches which turn them to on. The diodes keep that from occurring as current only flows one direction through the diode.
Printable View
OK thanks Bob. Does that mean you should always connect diodes to joystick buttons then?
Ken.
It depends on the way the manufacturer connects the switches to the interface. I have found for instance with CH Yoke, they use the matrix, and therefore they use diodes, Just count the number of wires going to the switches, and if there is less wires then switches then chances are pretty good there set up in a matrix, and therefore diodes are required. Keep in mind that a diode cannot harm anything. Better to be safe and put them in. :)
Thanks Trevor, that explains why I have found anomalies in some joysticks I've used. I have used diodes in one and not in others, and some are OK without them while others aren't. You're right though, they are a very inexpensive addition so might as well put them in.
Ta,
Ken.
The diodes did the trick. On a cpuple of buttons I had to put them on both wires in opposite directions. Thanx for all the help. When I get a chance I will post some pics of my force feedback stick on steriods...
Christopher