[sdiy] Force Sensing Resistor

Mon Sep 17 09:24:50 CEST 2007

Pictures sent. Had quite a lot of trouble sending them though (took a dozen 
attempts or more) so please let me know if you got them.

I think I really should pull my finger out and get that website up and 
running. Gotta be easier than sending out pictures individually all the time 
:o(

EK

----- Original Message ----- 
From: "JH." <jhaible at debitel.net>
To: "Synth DIY List" <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, September 15, 2007 2:37 PM
Subject: Fw: [sdiy] Force Sensing Resistor

> (I just saw your mail was cc'd to synth-diy, so I'm forwarding my response
> there, too.)
>
>
> Hi Edward,
>
> thanks for your mail - you're doing really interesting stuff!
>
> I have recently played a (broken) CS80 again after many years, and decided
> that I need such an expressive keyboard, too.
> Either I'll buy a CS-80 (maybe soon?), or I'll build my own keyboard.
> I wouldn't go so far as carving my own keys, though. Reusing something
> existent, rather.
>
> I'm pretty picky about keyboard action.
> Three that I like are
> CS-80
> Rhodes Chroma
> Wurlizer EP200
>
> What I *don't* like, despite them being loved by many piano players, are
> The Prophet T8
> The hammer action of mayny electronic pianos (my Kawai CA600 included)
>
> I tracked it down to what exactly it is that I don't like, and I think I
> found the difference:
> On many weighted, hammer-action type keyboards, you need a lot of force to
> just hold the key down.
> Ideally, the key should give resistance when you hit it, but then need 
> less
> force to keep it down.
> I really appreciate the keyboard action to be weighted for better dynamic
> control, but my fingers are not strong enough to play for a long time, 
> when
> a lot of force is needed for just keeping the keys down.
>
> I noticed that grand pianos and upright pianos can be very different in 
> that
> respect also, varying from model to model, and from manufacturer to
> manufacturer.
>
> On the CS-80, the keyboard action is very good for my taste, but the
> aftertouch is a little on the stiff side IMO. I'd love to have a sensitive
> aftertouch like the CS-50 has, but polyphonic.
>
> I'd love to see pictures of your work!
>
> Best regards,
>
> JH.
>
>
> ----- Original Message ----- 
> From: "Edward King" <edwardcking2001 at yahoo.co.uk>
> To: "JH." <jhaible at debitel.net>; <xyzzy at sysabend.org>
> Cc: "Synth DIY List" <synth-diy at dropmix.xs4all.nl>
> Sent: Saturday, September 15, 2007 11:40 AM
> Subject: Re: [sdiy] Force Sensing Resistor
>
>
> JH,
>
> Yes, Ive built my own keyboard (actually several now) from scratch the 
> hard
> way (wooden keys, partly machined and then hand finished + keytops etc).
> I dont recommend it.
> I dont regret doing it, but I actually lost hair during the course of the
> development and would only do it again for a "special" / "different" type 
> of
> keyboard. Some ideas I had included using replica fingerbones for a true
> "frankenstein" / Goonies type thing or hand carved keys for a "rustic" 
> look.
> The concept of combining organic look and feel with modern technology 
> lights
> my little candle.
> Im also still very taken with building a keyboard or two from composite
> materials or even glass.
>
> As to the sensing, monitoring and other control stuff, I really could 
> write
> a book. the conclusions I came to were as a result of years of testing
> different methods. At one point I even tried a sealed conductive liquid
> position sensor that my other half was kind enough to help develop with 
> me.
> It was not good.
>
> Eventually, I got stuck into the idea of optical measurement and initially
> went with the slotted optical transistor output sensors with vane attached
> to the lower part of the key (as per work done by Graham Hinton for a 
> breath
> controller in the eighties and the work done more recently by Adrian Freed
> at berkeley).
>
> The vane design was a royal posterior ache and hand-manufacturing 
> tolerances
> were laffable. I was eventually left with two choices: 1) have vanes
> lasercut or moulded specifically (quotes I got were ridiculous for the 
> size
> of the things) 2) go with optical distance measuring technology. I went 
> with
> the latter.
>
> I also decided to go with the Fatar TPM10 (hammer action weighted 
> keyboard)
> available through Doepfer for my prototype because I had the opportunity 
> to
> test one out a while back and liked it very much.
> Although I had difficulty dealing with Doepfer initially (confusion over
> where Im located because I have a uk email address, but dont live in the
> uk), they turned out to be very helpful, very professional and pleasant to
> deal with.
>
> The PCBs for my senso arrangements will be done by the time the keyboards
> arrive and as long as the spec hasnt changed, they should slot right in.
>
> Im happy to share my photos with you of the keyboard mechanisms I 
> designed.
> I dont have many (Im not much of a photographer) but I'll send them over.
>
> Either way, my advice to you is to either buy a midi keyboard and adapt it
> (cost anything from 30 bucks to 300 bucks) or go with the fatars from
> doepfer (800 bucks or thereabouts) because building your own is very 
> costly
> in terms of man hours lost sleep and wood splinters.
>
> Regards
>
> EK
>
>
>
>
> ----- Original Message ----- 
> From: "JH." <jhaible at debitel.net>
> To: "Edward King" <edwardcking2001 at yahoo.co.uk>; <xyzzy at sysabend.org>
> Cc: "Synth DIY List" <synth-diy at dropmix.xs4all.nl>
> Sent: Saturday, September 15, 2007 10:31 AM
> Subject: Re: [sdiy] Force Sensing Resistor
>
>
>>I came late into this thread. Edward, have you built your own keboard with
>> polyphonic aftertouch ?!
>> What keyboard action did you use to retrofit with QTC pills?
>> Do you have any pictures of what you've built?
>>
>> I thought the Pills respond in en exponential rathe than linear way.
>> Thought
>> I read this somewhere.
>> I've ordered some of these from Maplin yesterday. Curious to try them
>> myself!
>>
>> JH.
>>
>>
>> ----- Original Message ----- 
>> From: "Edward King" <edwardcking2001 at yahoo.co.uk>
>> To: <xyzzy at sysabend.org>
>> Cc: "Synth DIY List" <synth-diy at dropmix.xs4all.nl>
>> Sent: Saturday, September 15, 2007 5:42 AM
>> Subject: Re: [sdiy] Force Sensing Resistor
>>
>>
>> Hi Tom!
>>
>> Actually, although they make some products in the uk, they also have a
>> manufacturing unit in the far east (or at least in that direction).
>>
>> I went a bit overboard with them when I came acrross them and have given
>> proportional control to various objects that really shouldnt have
>> it....however....
>> Let me know if you want me to send you over a couple of samples as I've
>> got
>> to order some more in anyway.
>>
>> A nice quickie experiment (proof of concept) is find someone with a
>> slightly
>> earlier model car, pop off the electric window switch, shove a QTC pill 
>> in
>> between the contacts and hey presto! You have (or should have depending 
>> on
>> the car and switching arrangement) proportional electric window control
>> :o)
>>
>> for more relevant uses, the forum on peratechs website will be helpful in
>> getting the best out of the materials and if you want more hints and
>> practical advice, just gimme a shout. Remember, the output is
>> _very_nearly_
>> linear but not quite so for finer control, you need to tweak things a 
>> bit.
>>
>> EK
>>
>>
>> ----- Original Message ----- 
>> From: "Tom Arnold" <xyzzy at sysabend.org>
>> To: "Edward King" <edwardcking2001 at yahoo.co.uk>
>> Sent: Friday, September 14, 2007 5:32 AM
>> Subject: Re: [sdiy] Force Sensing Resistor
>>
>>
>>> On Fri, Sep 14, 2007 at 05:26:45AM +0300, Edward King wrote:
>>>> QTC cable is what Im using for keyboards that only need aftertouch for
>>>> the
>>>> whole board. For individual aftertouch (I can never remember whether 
>>>> its
>>>> called poly or mono) QTC pills.
>>>
>>> Oh.  Nifty, How did I miss this product??   Looks like its made in the
>>> UK?
>>>
>>>> Both QTC cable and QTC pills are very cheap and pretty linear.
>>>
>>> For Poly I'm back to playing with Hall Effect sensors since they have
>>> dropped in price.  I hope to have something to report soon...
>>>
>>> -- 
>>> --------------------------------------------------------------------
>>> - Tom Arnold           -  "...is it a virus, a drug, or a religion?"
>>> - Sysabend Caretaker   -    Juanita Shrugs. "What's the difference?"
>>> ------------------------       -- Neal Stephenson,  Snow Crash
>>>
>>>
>>
>>
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>>
>>
>>
>
>
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