Hi-

Me don't know much about this.  But I am into model trains - these days
they have brains in the form of PICs :-) and use H-bridges for the
motors.  Also, as the signal is transmitted on top of the track voltage,
we use H-bridges to do this too (1-10A is usual range).

Anyway, after looking though lots of circuits (on the web, at
manufacturing sites etc), and looking at High-Side drivers etc, one of
the simplest H-bridges is on the MERG site in Britain.  It uses a
CD40106 hex driver and a pair of N and pair of P-Fets:
http://home.freeuk.net/merg/resources/bc1asch.pdf  (it even uses a PIC
;-)

NB- the PIC is doing some important timing so that the upper and lower
Fets are NOT TURNED ON TOGETHER, otherwise large currents will flow, but
only for a short time.

David

Dan Michaels wrote:

> Roman wrote:
> >Hi Greg, (re h-bridge questions) have you tried
> >doing a web search for "h-bridge motor" or
> >"h-bridge circuit" ??
> >
> >I know there are some good circuits out there,
> >having come across them myself from time to time.
> >It would be nice if someone compiled these in one
> >place so the information was easily accessible.
> >I would do it but have been very busy the last
> >couple of weeks.
>
> Roman, I am surprised that "you" don't have this info on your
> page. I did a search to find some ckts to reference on my page:
>
> http://www.oricomtech.com/robolnk2.htm#Mot2
>
> Of these, the ones I found most compelling were:
>
> http://www.cadvision.com/blanchas/hexfet/h-bridge.htm
> http://www.dprg.org/hbridge.html
>
> [the last has a nice little ckt for sensing motor current].
>
> These show a p-chan MOSFET stacked above an n-chan, but
> unfortunately many show the drain of the p-chan connected
> to +V, rather than the source, so I am wondering what gives.
>
> - dan
> ===================
>
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