[sdiy] IN your mind, what is .... LM3900

[Scott Gravenhorst]

Magnus Danielson <cfmd at bredband.net> wrote:
>From: Scott Gravenhorst <music.maker at gte.net>
>Subject: Re: [sdiy] IN your mind, what is .... LM3900
>Date: Wed, 04 Feb 2004 12:19:43 -0700
>Message-ID: <200402042019.i14KJhd24670 at linux6.lan>
>
>> Dare I bring this back to actual synth-DIY?  
>
>Sure, confuse the hell out of us by bringing in the sexy chick of Synth-DIY!
>;O)
>
>> I had asked if anyone could describe what it is that the LM3900 was the
>> best choice for in analog synth design.  Paul Perry answered that the Serge
>> Wave Multiplier uses it, but other than that, there were no other
>> responses.  I'm assuming now that it isn't all that useful for analog synth
>> work other than the SWM module (which looks fun and simple).  This is
>> probably because it's a current input device, and apparently, there isn't
>> much need for a current differencing amplifier in analog synth electronics.
>>  My poorly wired cerebrum doesn't seem to pop out anything über-wonderful.
>
>But... didn't the ARP filter module use the LM3900? I seem to recall that...
>
>I'm sure you find the schematic on the web somewhere... I've seen it, but I
>don't recall the details very clearly... and I *AM* ashamed for that fact!

Thanks!

On this site is published a schematic of an ARP 4075  (Japanese text tho.):

http://www.asahi-net.or.jp/~WZ4K-TNK/diy/arpvcf.html

and an EFM page with what appears to be an adaptation of a 4072:

http://www.ele4music.com/vcf7b/vcf7b.html

I must say, this is a structure that I am not at all familiar with.

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