Re: [CAD_CAM_EDM_DRO] Opto Isolation ??

Mat:

Thank you for looking over my circuits and commenting. From the great
comments and tutorials I received I've updated them. If you get a chance
please take a look:

internet.oit.edu/~currinh/opto.html


At 01:16 AM 10/2/00 -0400, you wrote:

>What you've done looks pretty reasonable and would work fine for things like
>spindle_on, and lube_level_low. If you plan on using this opto device for
>something like the step signal, you might want to review the specs for rise
>and fall times of the output. I believe that they listed the typical tr and
>tf at 100uS. If that's really the case then your minimum pulse period would
>be 200uS which means a max step rate of 5kHz. Compare these times with the
>requirements of the chip you are driving on Dan's board such as max input
>rise and fall times, and any setup or settling time requirements.

I always think of electronics as instantaneous compared to mechanical
things, like steppers. But of course you are right. I changed this from
the darlington 2502 to the transistor 2501. The 2501 has rise and fall
times of 3 and 5 us which is quite a bit different than the 100 us.

>You'll also need a separate DC supply for the switch inputs, and there can't
>be any connection between the PC's ground and the DC ground in the machine.

I need a 5V supply for the driver boards and was planning to pull the
voltage for the switches from this??

>I'm way less squeamish about directly connecting the PC to external circuits.
>Instead of connecting your stuff to the built-in port on the motherboard, get
>one of those $8 parallel port boards you plug into a slot on the PC and use
>that.

Where are these available? For $8 or $20 I'd get one (or two) just
'cuz.

Thank you.

--------------------------------
Hugh & Denise Currin
currin@...
Klamath Falls, Oregon USA
541/884-3023
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