Re: [CAD_CAM_EDM_DRO] Re: Getting Parallel port to run relay

bertmantx wrote:

>How much current is required to fire 2222 xsistor?
>

5mA should put it into saturation pretty reliably.

You might need a pull-up or -down on the base, depending on the drive
charactaristics of the port (Its been quite a long time since I worked
with one, as I recall the one I was using had 1k pull-ups in the port,
which seemed pretty potent at the time).

>Any idea why transistor didn't fire with 5v to Base but did fire when colector and base were shorted?
>
>

Possibly your voltage is marginal for the relay you're using, that might
have just been enough to trip it over. If it stays on after you remove
the short (leaving the resistor driving the base) and still turns off
when you disconnect it, thats probalby it. Relays require more current
to trip over than they do to hold position.

>Just checked computer and the Parallel port tape goes directly to
>mother board - couldn't see manufacturer but its an AMD K6 2/500
>Processor. Will I still be able to add new parallel port to plugins
>such as the other cards are in video, sound card, usb(not needed)
>ect.?? or should I start looking for new motherboard??
>

As long as you have an open PCI slot you can add an expansion card with
a new port on it.

Incidentally, a USB port is a great place to get power, you can often
get up to 500mA from them.

CS