[sdiy] keyboard question and generating cv

[Tom Wiltshire]

I agree that you wouldn't want cv voltage going through the rubber  
contacts. I'd assumed that you'd arrange the rubber buttons as a  
matrix, scan the matrix, and then produce a cv given the result.
The old fashioned way of precision resistor chain coupled with  
conductive rubber buttons sounds like a disaster.

T.

On 13 Apr 2009, at 11:31, dragons wrote:

> Hi,
> well I agree with Samppa here.
> it depends on the circuit used for generating the cv voltage.
> I think that a lot of the circuits would " assume" that you are  
> going to be using a switch that has a low consistent resistance  
> when pressed.
> and the contacts that work by having a conductive pad on the pcb  
> and conductive pads on the rubber contacts simply don't have a  
> consistent resistance when pressed.
> this would probably give problems generating a CV voltage.
> using reed switches / metal contacts is a much better way of doing  
> things. the only reason why commercial manufacturers don't use  
> these is down to cost.
> regards Peter B
>
>
> Ian Smith wrote:
>> Hi all,
>> I'm thinking of making a controller for my synth. I'm going to  
>> fashion it after a concertina. It's going to be a CV controller,  
>> not MIDI.
>
> I want to etch the buttonboard like a commercial keyboard to reduce  
> the amount of rat's nest. My question is this:
>
> The black stuff that covers the contact points on commercial  
> keyboards, what is it? where do I get it? and Is it really necessary?
>> -Ian Smith
>> _________________________________________________________________
>
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