[sdiy] Another "which chip" question

[Scott Gravenhorst]

Yes, 7555.  The FatMan synth perfectly demonstrates why you don't want to use the bipolar 555 for
the reason that Paul S. mentioned.  There was a bypass method using a LED and a 100uF cap that
prevented most of the problem, but when I tested the 7555 in the FatMan VCO circuit, the soft sync
problem was virtually gone.

As far as VCOs go, the 7555 being CMOS has a comparator that draws less current than the bipolar
555 comparator, so a VCO built around a 7555 should be more linear than one built around a 555.

Scott Stites <scottnoanh at peoplepc.com> wrote:
>Hi Larry,
>
>I use the 7555, which has a very low current drain and is very 
>kind to the PS rails. I learned about these from Rene Schmitz, 
>who uses them in his VCO3 for just that reason. Jameco has them 
>with a very good price. Mouser has them, too. Dual variant is the 
>7556. 
>
>Cheers,
>Scott
>
>
>-----Original Message-----
>From: "J. Larry Hendry" <jlarryh at iquest.net>
>Sent: Oct 13, 2004 12:07 AM
>To: synth DIY <synth-diy at dropmix.xs4all.nl>
>Subject: [sdiy] Another "which chip" question
>
>I'm planning some simple clock circuits with 555 and the dual version 556
>chips.  I seem to recall some discussion here about one version of the 555
>being a rather nasty player.  Someone care to recommend a particular one of
>the many variations of these puppies?  Or, something I should stay away
>from?  I'm using +/- 15 VDC supply.  So, most any Vcc is OK.
>
>Thanks
>Larry Hendry
>www.wiseguysynth.com
>
>
>
>
>
>
>________________________________________
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