Thanks for you well formulated question Dan that brought the right answer.
I have been looking for the H-Bridge of this type of servo for a very long time :))

Trough Alexandre's link I have found that both circuits BAL6686 and BA6688 are available from
http://www.angelfire.com/biz/techsonic/page2.html.
The BAL6686 is also available from Futaba for 3.75USD

Thank you guys,
Gaston.

Dan Michaels wrote:
>
> Rich Ottosen wrote:
> >Dan:
> >The Signetics data books I have show the NE544 the schematic for its
> >use. There is also application note AN133 that gives more detail on how
> >to use the chip. Very informative.
> >
> >If you can't find the data elsewhere then I can scan it for you.
> >
>
> Many thanks to Mike and Dale and Rich for your responses.
>
> Alexandre's link provided the schematic for the exact servo I have,
> Futaba S3003. It uses one BAL6686 h-bridge and one BA6688 servo control
> chip. I assume the 6686 has clamp diodes built-in, but I'll have to see
> if I can find the specs. Other than that, it looks like the only
> built-in noise suppressor is a cap across the motor - value unknown.
>
> I guess I don't need an NE544 datasheet, but it would be interesting
> to know what sort of noise filters might be present in the servos
> that use that chip.
>
> I think Drew might also use some help in designing a good filter for
> his servo problem on the other thread.
>
> thanks,
> - dan michaels
> www.oricomtech.com
> =========================
>
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