Re: [LAU] another control surface question

On Fri, 4 Jul 2014 06:55:45 +0000
Fons Adriaensen <fons@email-addr-hidden> wrote:

> On Thu, Jul 03, 2014 at 01:58:02PM -0700, Len Ovens wrote:
> > On Thu, 3 Jul 2014, Fons Adriaensen wrote:
> >
> > >It all seems a nice idea, but OTOH you can get a Yamaha motorised
> > >fader for 20 Euro, see
> > ><http://www.thomann.de/it/yamaha_ls_901vmotorised_fader.htm>.
> > >
> > >I wonder if you can get and assemble all the required parts for
> > >a usable 'belt fader' for that price.
> >
> > That is about the same price I was looking at for motor faders to.
> > But... that is not the whole story... You need also the driver for
> > the motor, a touch sensor so it knows you are controling it and
> > don't burn the motor out trying to go against your movement and you
> > also need an analog in port. Also needed is the circuitry to receive
> > the virtual fader position from where ever and apply it to the fader
> > logic. SO the fader is $20, but the whole price is closer to $50
>
> I don't think so. You need an 'H-bridge' for each motor, an LN293
> (IIRC) has two of those and costs around 2 Euro. Then you need an
> AD converter which can be multiplexed and doesn't need to be very
> high speed. Something with 8 channels, 12 bits will be less than
> 1 Euro per channel. Then the touch sensor, again this can be done
> for around 1 Euro per channel. All the rest you need anyway, or
> can be SW. So a pessimistic guesstimate would be 25 Euro per fader.
>
> Ciao,

Not forgetting of course that doing it different is fun :)

You can't put a price on that, and I'll say right now, there is a lot of kit
I've built that is totally uneconomic, inefficient and unrepeatable. However, I
use some bits every day and am quite proud how well it has stood up over time.

Back to the belts.

I'd cut slots in the top plate (you'd have to anyway to get the belts and
pulleys in), then put a strip of (say) 6mm thick nylon or PTFE on the underside
of the top plate. The belts will hide it and will slide smoothly over it. Using
the toothed side against encoders with toothed pulleys means the belt can be
quite slack without slippage.

-- 
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
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