[sdiy] Legal issues of cloning

[ASSI]

On Sunday 06 October 2013, 10:59:07, Tom Wiltshire wrote:
> For synths, the Moog filter is the most famous example
[...]

If you refer to US3,475,623 then the claims (which describe what is actually 
patented) never reference the ladder filter that's become known as the Moog 
ladder.  This enters the schematic shown in the patent and the accompanying 
description of how it workd into the state of the art with the date of the 
patent filing.  The actual independent claim is for using the dynamic 
resistance of the base-emitter diode as the voltage controllable resistive 
element of an RC filter.  Roland (and probably others) worked around that 
claim by using a plain diode instead of a transistor.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

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