Re: [CAD_CAM_EDM_DRO] Re: Clarifications needed -

On Fri, 12 Sep 2003 21:40:03 -0600, you wrote:

>> Now I'm confused.
>> I thought it was either ground from the parallel
>> port, or +5V from the compueter power supply?
>
>When a pin goes high it is at +5V (well it should, but some systems
>don't make the full swing), but there is not enough current from the pin
>for more than one LED. G201s are wired to use a common +5V and switch on
>the LED in the opto when the pin goes low and current flows to it.
>G210's can be set up to use the current from the pin with a common
>ground.

One thing to remember is that an average TTL gate can sink 16 ma, but
only source 400 or so ua....

Hence it's much preferred to sink the current from another 5 volt
supply.

Harvey

>
>Tim
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