555 + transistor VCO

[Scott Gravenhorst]

National Semiconductor Linear Integrated Circuits manual,
pp. 4-14.  There is a linear ramp circuit that uses a 555 and
an extra transistor to source the charging current for the
integration cap.  You can also get the datasheet at:

http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM555.pdf

The circuit is on page 9.

This is a fixed osc, but how much would it take to make it
VC??  There's also the PAiA FatMan way, it's a VCO, but uses
an opamp package and 2 trannies.

Paul Perry <pfperry at melbpc.org.au> wrote:
>I seem to remember a simple 555 sawtooth VCO using 
>a transistor as a constant current source to 
>straighten out the saw. Any pointers? Cant find it in my
>files..
>I'm just looking for a very simple VCO saw, need not be 
>at all accurate.
>
>paul perry melbourne australia
>
>

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