[sdiy] Circuit Boards / kits

[harrybissell at wowway.com]

ARP usually used the LM301 opamp. They would look similar. In many
cases the LM301 is feedfoward compensated (makes it faster).

The 748 is a decompensated 741, its faster but not unity gian stable
unless you add the right compensation cap (like PAiA did)

H^) harry



On Thu, 25 Sep 2008 11:38:40 -0400, David Moylan wrote
> Roy J. Tellason wrote:
> > On Thursday 25 September 2008 08:33, harrybissell at wowway.com wrote:
> >> On Wed, 24 Sep 2008 18:22:38 -0400, Roy J. Tellason wrote
> >>
> >>> So what do they use for a VCA?
> >> A differential pair, a transistor to sink current through the emitters,
> >> and an opamp to revover the signal.  I added 1% resistors and it works
> >> very well.  I think its a 741 (or 748)
> > 
> > I have a vague recollection of seeing something of the sort before.  I
think I 
> > had a TI book that featured a circuit like that.  I haven't seen it lately so 
> > I don't recall what particular amplifier it used or whether it used 1% 
> > resistors though.
> > 
> >> schematics are online (somewhere)
> > 
> > Hmm.
> > 
> Didn't Arp use this configuration too?  I know there are some of 
> this type in the Omni2.
> 
> Dave


Harry Bissell & Nora Abdullah 4eva