ARP vs. Moog (nice title, innit?)

[Gene Zumchak]

Hi Joachim,

    Moog must have had a lousy lawyer.  Moog used the dual transistors
for exponential from the very beginning, and he was out there a few years
before ARP.  If ARP had patented it, how could it hold up if there was a
product on the market already using it?  Since I haven't seen the ARP
patent, I don't know what it claimed.  Log/antilog techniques are
detailed in National Semiconductor AP note AN-30, but a dual transistor
circuit appeared in AN-4 from April 1968.  I believe AN30 predated ARP's
business.  What is the date on the ARP patent?

Gene Z.



Joachim Verghese wrote:

Joachim Verghese wrote:

> Hi,
>
> > I take exception to the idea that Moog might have borrowed anything
> > from ARP.
>
> But then again, you might infringe on someone's patent even if
> you don't explicitly borrow.
>
> I think the deal was that Moog started compensating their
> exponential converters around the time the Minimoog was
> born, using the dual transistor scheme we're all familiar with
> now.
>
> As it happened, Alan Pearlman already had a patent on a
> circuit like that (US pat #3,444,362), so ARP could use this
> as an argument when faced with Moog's filter lawsuit in the
> early '70s. The outcome, as I understand it, was a mutual
> agreement to drop charges.
>
> I guess ARP could have continued using Moog's ladder circuit,
> but instead they designed a new filter from scratch, a circuit
> that became the basis for the 4072/4075 modules. (ARPtech
> website update just around the corner, I promise! :-)
>
> cheers,
>
> -joachim