Re: [CAD_CAM_EDM_DRO] Re: spindle start and stop

>
> I have run into a number of parallel ports that don't source enough to

turn

> on the solid state relay.

Here, I think it also depends on what SSR you have. I looked at specs on
several
and found that some require as much as 30mA to fire. Not many parallel
ports will
do this.

>But, it is very easy to use the port to drive a small transistor and have

the transistor

>trip the relay.

Another solution is to set the port up as a sink instead of a source. Put a
resistor and
5V supply in series with the SSR. The original port used a 74LS374 which
could
source 2.6mA and sink 24mA. Newer ports use a single chip, though they
should still
be capable of sinking as much.

Doug Harrison