[sdiy] Substitute for pin matrixes?

[Derek Holzer]

Totally fascinating, thanks to you and Magnus for the enlightenment!

D.

Aaron Lanterman wrote:
> On Jan 23, 2010, at 11:14 AM, Derek Holzer wrote:
> 
>> In this vein, can anyone tell me how the program cards for the Buchla Music Easel work?
>>
>> FROM http://www.buchla.com/historical/music_easel/music_easel.html
> 
> I've see Magnus has already responded to this - I'll just throw in a couple other notes...
> 
> The individual daughterboards tend to have inputs that are (more or less) like op amp summing nodes on an inverting op amp configuration. One resistor is off-board and hooked to the front panel pots (which have a couple of additional tapering resistors), and another resistor, if used, it on the card. A +13.5 V supply can be fed to the front panel sliders and/or the resistors on the card, or both, as determined by a switch. The summing aspect lets you pile the front panel setting *on top* of what is set by the card. Choosing different resistor values on the card lets you emulate various slider settings. 
> 
> The switches on the front panel (to select filter routings, etc.), for the most part, don't hook dircelty into the sound generating circuitry - they create settings for various CMOS switches, so the CMOS switch settings can be set by resistor values on the card.
> 
> It's quite clever - and from the card you can do all sorts of things that you can'd do from the front panel.
> 
> - Aaron


-- 
::: derek holzer ::: http://macumbista.net :::
---Oblique Strategy # 93:
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