4x4 keypad with isolation diodes - where can you get em?

OakGraphics

Howdy,

I am looking for 4x4 keypads with isolation diodes on each key (16 buttons, 16 diodes) for a project of mine that seems to need the diode isolations.
Before I design my own 4x4 keypads in a pcb, I was wondering if anybody had run into this part. :-)
·

Lee Harker

Maybe you could give a few more details on your application. Usually a 4x4 keypad is arranged in a matrix to reduce the number of pins needed to implement it. You may find that there is a way you could use it as is with a different wiring menhod.

LoopyByteloose

How about posting a schematic? It seems to me that you could add your own diodes for isolation. AS that would be about 4 diodes, I am wondering if you got something exotic.

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Mike Green

The diodes are only needed when you expect more than one key to be pressed at the same time and you want to identify which keys are down and which ones are not. Without the diodes, you can get false readings when more than two keys are pressed at the same time. For most situations, this is not important enough to justify the cost of the diodes.

OakGraphics

That is exactly what it is for, a way to check all the buttons at the same time, including multiple keypresses.· Here is a schematic of what it looks like.·



I typically wire the buttons for a custom controller, and panels so they are not usually all together, but I would like to test my cable harness before I place it, so I thought a 4x4 keyboard matrix would be perfect for this.

Post Edited (OakGraphics) : 7/6/2007 6:56:54 PM GMT