CAD CAM EDM DRO - Yahoo Group Archive

Re: Parallel Port Interface

on 2001-11-03 12:37:36 UTC
Hi Doug,

the '132 is a NAND, but I think you're confusing it. Gnd a NAND input,
and you get nothing through. Tie an input HI, and the signal goes
through INVERTED. Now a '136 is an EXCLUSIVE-OR gate, and work similar
to what you're saying. Perhaps that's the one you're thinking of?

Alan KM6VV


Doug Fortune wrote:
>
> currinh@... wrote:
> >
> > For what it is worth, here's what I've done.
> >
> > I designed and built the opto-isolation circuit (quite
> > an accomplishment for me) and this worked well. However,
> > it inverted the signals and EMC did not like this.
> >
>
> I think I suggested this idea before (using single ended signals,
> buffering them to higher strength, and using a Schmitt trigger
> type device (with built in hysteresis):
>
> Using a 74LS132 quad 2-input positive NAND Schmitt trigger TTL
> chip (under a buck), you can use it this way:
>
> As it is a NAND, if you hook one input up to GND and the other
> input to your signal (and I am presuming this chip is right next
> to the encoder, for buffering the signal down to your driver/PS
> box), then you get:
> - the buffering
> - Schmitt trigger hysteresis (good for noise reduction)
> - the signal is NOT INVERTED.
>
> However, if you do want the signal inverted (to fix the problem
> above where EMC, or some other program, doesn't like it some
> particular way) hook one input up to +5, and the other input to
> your signal, then you get:
> - the buffering
> - Schmitt trigger functionality
> - the signal is INVERTED.
>
> In fact, since the chip has 4 NAND circuits, you can hook a
> circuit up both ways when you originally solder it together,
> and select what you want (Inverted or Not Inverted) to suit
> the circumstances.
>
> Doug Fortune
> http://www.cncKITS.com

Discussion Thread

Gary.Rose@c... 2001-11-03 07:07:21 UTC Parallel Port Interface Art Fenerty 2001-11-03 07:14:30 UTC Re: [CAD_CAM_EDM_DRO] Parallel Port Interface currinh@O... 2001-11-03 09:04:22 UTC Re: Parallel Port Interface Tim Goldstein 2001-11-03 10:06:59 UTC RE: [CAD_CAM_EDM_DRO] Re: Parallel Port Interface currinh@O... 2001-11-03 10:26:04 UTC Re: [CAD_CAM_EDM_DRO] Re: Parallel Port Interface Doug Fortune 2001-11-03 10:42:59 UTC Re: [CAD_CAM_EDM_DRO] Re: Parallel Port Interface cncdxf@a... 2001-11-03 11:07:13 UTC Re: Parallel Port Interface Alan Marconett KM6VV 2001-11-03 11:40:32 UTC Re: [CAD_CAM_EDM_DRO] Parallel Port Interface Gail & Bryan Harries 2001-11-03 11:46:19 UTC RE: [CAD_CAM_EDM_DRO] Parallel Port Interface Alan Marconett KM6VV 2001-11-03 12:37:36 UTC Re: Parallel Port Interface Alan Marconett KM6VV 2001-11-03 12:58:09 UTC Re: [CAD_CAM_EDM_DRO] Parallel Port Interface Rose, Gary 2001-11-04 14:41:12 UTC RE: Re: Parallel Port Interface JanRwl@A... 2001-11-04 18:51:39 UTC Re: [CAD_CAM_EDM_DRO] Parallel Port Interface JanRwl@A... 2001-11-04 19:01:58 UTC Re: [CAD_CAM_EDM_DRO] Re: Parallel Port Interface JanRwl@A... 2001-11-04 19:03:24 UTC Re: [CAD_CAM_EDM_DRO] Re: Parallel Port Interface JanRwl@A... 2001-11-04 19:22:10 UTC Re: [CAD_CAM_EDM_DRO] Re: Parallel Port Interface