Re: gEDA-user: challenge board ALMOST works

[Werner Hoch <werner.ho@xxxxxx>]

Hi DJ,

On Monday 11 September 2006 16:42, DJ Delorie wrote:
> Werner Hoch <werner.ho@xxxxxx> writes:
> > When I'm using 7414 as oszillator I usually use the third circuit.
> > This only works with IC's that have schmitt-trigger inputs.
>
> What values (or ratios) of R3 and R2 do you use?  

Depends on the frequency and the capacitor ;-).

The resistor R2 is only there to improve the symmetry of the output 
pulse/gap ratio.
You can just remove it if you don't need exact symmetry.

R2 is usually 10 times larger than R3.

> I assume R2 is 
> large, since it's configured as a voltage divider, but I'm trying to
> keep R3 large too to get a low frequency out of such tiny parts
> (0.01uF is the largest 01005 they make).

Why in hell do you use such damn small parts ;-).

regards
Werner


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