Switch array for keypad emulation


I'm trying to use an Arduino to interface to the controller board of my dryer. Input is captured through a collection of tactile dome pushbuttons wired in a 3x6 array (9 wires). I want to emulate button presses by momentarily shunting any pair in the array. Does anyone know of a simple circuit suitable for this purpose?



Put an FET across each contact and apply a voltage to the gate to turn it on. For better isolation use an optically coupled FET.

Thanks for the reply, Mike. I was hoping there was a good way to get it done with only a few parts. Basically, I've got 3 sources and 6 sinks. I was thinking something like a Darlington array might work, but I would need 6 of them since they generally share a common sink. I thought there might be a part I could use with each of the 3 sources, but I haven't come across anything. I've also had a heck of a time finding any kind of SSR or FET array that comes more than one or two to a package. I thought there might be something obvious that I was overlooking.

Something like the MT8806 (8x4 multiplexed analog switch array) looks like it would be ideal - 8 bit control over the whole array. But I can't find it anywhere.


I think I’ll try using 3 of these: