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scott wrote:
>> How hard would it be to get a couple of pressure sensors, and wire
>> them up to a MIDI plug so you could have your own?
>
> That's what I thought the moment I saw it. Or maybe simpler to buy a
> standard cheap MIDI keyboard to get all the electronics and rig up some
> nice wooden pedals to it.
Ooo, hey! Maplin had a roll-up keyboard MIDI-controller thingy. Add some
mechanical linkage and some springs and you got a MIDI peddalboard. :-D
The only *minor* detail that remains is... building a peddalboard in the
first place. :-/
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> I'm guessing generating MIDI signals in software is going to be
> intractable.
http://msdn.microsoft.com/en-us/library/ms711640(VS.85).aspx
I believe also if you have access to DirectX on your system then DirectMusic
offers a higher level interface to the MIDI controller.
> For one thing, it's going to take some big chunks of solid wood, and a big
> iron bolt.
An M4 or M6 standard steel bolt will do, you're not going to be levering up
cars with this thing!
> Given how ludicrously expensive actual wood is,
It's only expensive *after* someone has spent time shaping it and treating
it. Raw wood is pretty cheap, I would imagine that enough for a set of
pedals is not going to cost more than fifty quid. It's up to you how much
time you then want to spend shaping and treating it.
> I guess it might not even come out any cheaper than just buying the one in
> the shop...
Oh it will definitely come out at least an order of magnitude cheaper, but
of course it's going to take some time and skill on your part...
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>> I'm guessing generating MIDI signals in software is going to be
>> intractable.
>
> http://msdn.microsoft.com/en-us/library/ms711640(VS.85).aspx
>
> I believe also if you have access to DirectX on your system then
> DirectMusic offers a higher level interface to the MIDI controller.
http://msdn.microsoft.com/en-us/library/dd551276(VS.85).aspx
"Warning: This technology is deprecated as is all of DirectMusic."
Gee, thanks for telling us what the recommended alternative is. :-P
I wonder though... I've always thought of writing "fancy" Windows
programs as intractable, since it requires calling the Win32 API, and
very few useful programming languages can do this. However, I did
successfully write a Haskell library that talks to the Windows console
functions, and it worked fine. I wonder if it's really possible to write
a Haskell library that does something nontrivial like sending and
receiving MIDI messages?
>> For one thing, it's going to take some big chunks of solid wood, and a
>> big iron bolt.
>
> An M4 or M6 standard steel bolt will do, you're not going to be levering
> up cars with this thing!
I'm guessing you can't buy that stuff at the local hardware store though.
>> Given how ludicrously expensive actual wood is,
>
> It's only expensive *after* someone has spent time shaping it and
> treating it. Raw wood is pretty cheap, I would imagine that enough for
> a set of pedals is not going to cost more than fifty quid. It's up to
> you how much time you then want to spend shaping and treating it.
Well, I don't have to worry about splinters. ;-) I suspect cutting it to
a precise shape isn't going to be easy though. Hmm, I'll have a think
about it.
>> I guess it might not even come out any cheaper than just buying the
>> one in the shop...
>
> Oh it will definitely come out at least an order of magnitude cheaper,
> but of course it's going to take some time and skill on your part...
Indeed.
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> http://msdn.microsoft.com/en-us/library/dd551276(VS.85).aspx
>
> "Warning: This technology is deprecated as is all of DirectMusic."
>
> Gee, thanks for telling us what the recommended alternative is. :-P
Hehe yes true, it doesn't look like they do suggest an alternative for
communicating with MIDI hardware!
> I wonder though... I've always thought of writing "fancy" Windows programs
> as intractable, since it requires calling the Win32 API, and very few
> useful programming languages can do this. However, I did successfully
> write a Haskell library that talks to the Windows console functions, and
> it worked fine. I wonder if it's really possible to write a Haskell
> library that does something nontrivial like sending and receiving MIDI
> messages?
It should be no problem if you can call Windows API functions, the ones for
MIDI control are all still there.
>> An M4 or M6 standard steel bolt will do, you're not going to be levering
>> up cars with this thing!
>
> I'm guessing you can't buy that stuff at the local hardware store though.
Of course you can and they're dead cheap, B&Q will have a good supply of M4
and M6 bolts (plus many other diameters) at all sorts of lengths and head
types. They do nuts and washers too.
> I suspect cutting it to a precise shape isn't going to be easy though.
If you're making a load of pedals then I would be tempted to first make a
jig so that you can cut each one to exactly the same dimensions. You can
finish them off with some sand paper or an electric sander (more expensive
but faster).
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>> "Warning: This technology is deprecated as is all of DirectMusic."
>>
>> Gee, thanks for telling us what the recommended alternative is. :-P
>
> Hehe yes true, it doesn't look like they do suggest an alternative for
> communicating with MIDI hardware!
That was the conclusion I came to also, yes.
Their main section on MIDI control still mentions the same function
names, so...
http://msdn.microsoft.com/en-us/library/ms712733(VS.85).aspx
>>> An M4 or M6 standard steel bolt will do, you're not going to be
>>> levering up cars with this thing!
>>
>> I'm guessing you can't buy that stuff at the local hardware store though.
>
> Of course you can and they're dead cheap, B&Q will have a good supply of
> M4 and M6 bolts (plus many other diameters) at all sorts of lengths and
> head types. They do nuts and washers too.
B&Q sell nuts and bolts, but I doubt they sell large pieces of metal
such as random poles and rods.
>> I suspect cutting it to a precise shape isn't going to be easy though.
>
> If you're making a load of pedals then I would be tempted to first make
> a jig so that you can cut each one to exactly the same dimensions. You
> can finish them off with some sand paper or an electric sander (more
> expensive but faster).
My dad probably already has an electric sander or five.
I think the basic problem is that even if I do all this, it's never
going to be exactly like a real organ peddalboard. The whole point of
practicing is to get used to the feel of the real thing, so... I guess
I'll just stick to sneaking into the local church on saturdays. Much
cheaper. ;-)
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> B&Q sell nuts and bolts, but I doubt they sell large pieces of metal such
> as random poles and rods.
I suspect they do actually, but I wouldn't do it with those. I would get a
sheet of wood about 20 or 30mm thick to use as the base board. I would then
get a thin strip of aluminium (25x2 cross section would be perfect, I got
metre lengths of that from B&Q before), cut it into perhaps 150mm lengths
and bend it into a U shape. The bottom of the U I would bolt onto the base
board for each pedal, then fix an M4 bolt horizontally across the top of
each U with the pedal mounted on it so it's free to rotate.
> My dad probably already has an electric sander or five.
Job done then!
> I think the basic problem is that even if I do all this, it's never going
> to be exactly like a real organ peddalboard.
Isn't there any way you can replicate what the pedal is actually connected
to in a real one? It shouldn't be hard to think of something to replicate
the feeling.
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>> I think the basic problem is that even if I do all this, it's never
>> going to be exactly like a real organ peddalboard.
>
> Isn't there any way you can replicate what the pedal is actually
> connected to in a real one? It shouldn't be hard to think of something
> to replicate the feeling.
I was thinking that I'll never get the exact spacing between the notes,
the curvature of the peddals, etc. exactly right.
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> I was thinking that I'll never get the exact spacing between the notes,
> the curvature of the peddals, etc. exactly right.
There's probably some design information on the internet somewhere that can
help you out with that. Or just take a ruler and a notebook one time to the
church...
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Invisible wrote:
> Chambers wrote:
>
>> How hard would it be to get a couple of pressure sensors, and wire
>> them up to a MIDI plug so you could have your own?
>
> Harder than you'd think.
>
> A peddleboard needs to not break when an 80 Kg person stamps on it. This
> is non-trivial.
Not necessarily. If, as you stated, all you need to do is close a
circuit... well, you can do that quite easily.
> Where the hell do you buy pressure sensors?
Take apart any electronic scale, if you must. Other than that, I'm sure
Radioshack has them (though I don't know about the tolerances of their
models).
> You realise that MIDI is a serial communications protocol, right? It's
> not like you just connect each sensor to a different pin on the plug;
> you need some fairly elaborate electronics in there.
Good point; maybe just wire it up to a parallel port, then, and generate
the MIDI signal via software.
Or, put something together with that breadboard you've been playing with ;)
>> Then you could go to the pub and tell some random girl, "Hey, baby,
>> you ever dated a guy who wired his own base?" :)
>
> *facepalm*
What, girls like a guy who can get things done! :)
...Chambers
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Invisible wrote:
> Where the hell do you buy pressure sensors?
>
My choices are places like Adafruit and Sparkfun. Digikey, Mouser for
bulk parts, or for catalogs that are great brainstorming material (open
to random page, what could this part be used for). Radioshack if you
must. Or call a company that makes the sensor and ask for some samples
for a project you are developing.
Thinking about it, I don't know that I would use pressure sensors unless
you wanted pressure measurements. I don't know if that would matter for
pedals, as the pressure is going to be checked only once you have
already pushed it down. Simple dial resistors on each pedal would tell
you how far down they were pressed; optical encoders would work too
(dead mice scroll wheels, if you want those cheap). For more accuracy
than that, I would have to think about it more. Magnetic sensors might
work, but you would have to calibrate the whole set.
> You realise that MIDI is a serial communications protocol, right? It's
> not like you just connect each sensor to a different pin on the plug;
> you need some fairly elaborate electronics in there.
>
At the very simplest form, one input pin on any ol' micro-controller for
each pedal. If you have a force sensitive resistor (basic pressure
sensor) that is high resistance with no pressure and low when it has
pressure, use it to pull the pin low when pedal is pushed.** Wire it
differently if the sensor is different. Controller can just poll each
pin, or batches of pins where speed is an issue, and create the MIDI
packet to send. And if you are really set on having X packets per
second, the poll routine just stores the bits, and a timer interrupt
creates and sends the packet. Just make sure to have an optoisolator on
. . . crud, it has been forever since I did anything MIDI, I don't
remember if it is on the TX or RX wire.
Throw a multiplexer in, and you could use fewer i/o pins at the cost of
extra cpu cycles switching and waiting on the multiplexer. Going the
other way, a bigger chip so you can use 4 8-bit reads to get 32 pedals.
Or, really fancy, a 16 or 32-bit controller.
Elaborate? $8 micro-controllers are absurdly powerful now, and very easy
to program. Granted, most of the time it is assembly or some odd looking
java-esque language, but GCC will cross-compile to AVR and ARM chips.
The soldering might be tough, but for a prototype just breadboard it.
**I think that would result in less power drain than the other way
round, but I hack at these kinds of things, I don't engineer them.
Current limiting resistor on either supply or ground side, depending on
where you put the sensor, of course.
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