Randy? KeyWiz + Shazzam key... Can I?

[Lilwolf]

I'm working on converting a jukebox.  So I don't care about ghosting or anything.

Could I hook the shazzam key without diodes on a bunch of keys making the eco version really a 2x20 matrix encoder?  (or more what I would do is a 2x10 + 10).

So I would have the ground on all of the inputs.  Then Each button (that is replicated) would be on 2 buttons other side.  Then every other button would have a shazaam key hooked to it...  so pressing every other button would press the button plus the shazaam key. 

This should work right?

I have buttons A - (A+18) and then 0-9.  I was going to have 0-9 hooked directly since they are pressed with the others.. .Then I would have A hooked to 0, B hooked to shaz AND 0, C hooked to 1, D hooked to shaz AND 1... ect.

it seems like this would work out.  Am I missing something? 

btw, I never expect more then one letter pressed at a time... Or more of I don't care if one is pressed and the other is ignored....

Thanks!

[RandyT]

You would have a problem doing this if you didn't use diodes.

If you connect an input to 2 buttons and then connected the Shazaaam! input to one of them, you would also be making a connection with the other.  In a nutshell, if you pressed either button, you will get the Shazaaam! definition.  Connect more this way, and you would get every button showing as pressed when you pressed only one.

How many buttons are you trying to get in total?

RandyT

[Tiger-Heli]

Bottom line is you could get a max of 52 inputs out of the KeyWiz with this method, (the 32 standard plus the 20 Shazaaam'd).  This would require 40 diodes at an approximate additional cost of $4.00.