Re: Dumb question on TTL control of a relay from parallel p...

Thanks for the prompt advice. I came across a site (in Australia)
which offers the following board fully assembled (in an enclosure)
for $47US delivered to the States. I'm planning on using the
interface with MACH1/2 and I assume the outputs would be compatible.
Please let me know if the circuit makes sense and maybe I'll build a
three relay version (all I really need). It might cost almost the
same by the time I get done buying the stuff from Digikey and
practicing my almost non-existent soldering skills on it.

http://dontronics.com/diyk165.html
http://www.kitsrus.com/pdf/k74.pdf

Thanks and regards,
Jeff

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:
> In a message dated 9/9/2003 8:27:40 AM Central Standard Time,
> jeff@w... writes:
>
> > If the above current is too high, is it best to try to find a
> > miniature reed relay to control the coil of the "power relay" or
is
> > there a better way?
> >
>
> Jeff: The ULN2003 has SEVEN Darlingtons, any ONE of which could
control
> SEVERAL of those relays connected in parallel. A miniature reed-
relay might
> "theoretically" work (so long as the proper "spark suppression
diode" is used
> across it), but when controlling heavier loads, SOME very tiny reed-
contacts will
> WELD. But perhaps not with an INDUCTIVE load? The ULN2003 is a
better idea.
> An alternative with only TWO "relay drivers" is the 75477 8-pin DIP.
>
>
> [Non-text portions of this message have been removed]