Re: [CAD_CAM_EDM_DRO] TTL to HTL signal conversion

There is a dandy little series of ICs (75451, 75452 . . .) that take a TTL
input and can drive outputs configured to ~ 30V. I find them very useful.

D.

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, February 05, 2004 9:48 AM
Subject: Re: [CAD_CAM_EDM_DRO] TTL to HTL signal conversion


>
>
> Lars Levin wrote:
>
> >Hello Group!
> >
> >I have a couple of old servodrives with step/direction
> >inputs, but they use HTL signals, logic high is 24v
> >instead of 5v.
> >I want to be able to connect these to the parallell port,
> >and therefor need some converter.
> >Is there anybody that have some schematics or ideas for
> >a preferably opto isolated 5v to 24v and 24v to 5v converter.
> >
> >
> Assuming the speed is moderate, you can build this pretty easily.
> The parallel port doesn't have enough current capability to operate
> many opto-couplers properly. But, if you use an external source
> of +5 V, such as a hard drive connector or pin 1 of the game port,
> through the LED on the opto-coupler, a series resistor and then to the
> parallel port output pin, you get the highest current drive.
>
> Digi-Key has the H11A817D which should be suitable for this purpose.
> The wiring would be as follows :
> Pin 1 goes to +5 V.
> Pin 2 goes to one end of 510 Ohm resistor.
> other end of resistor goes to parallel port output pin.
>
> And for the output :
> Pin 4 goes to the HTL imput.
> Pin 3 goes to the ground of the driver.
> If the driver needs a pull-up to 24 V, you'd need an appropriate resistor
> from +24 V to pin 4. Something like 5 to 10 K Ohms would be a good
> guess.
>
> The polarity will be as follows :
>
> When the parallel port pin is at 0 volts, the LED will light, and the
> HTL signal will go to 0 volts.
>
> Jon
>
>
>
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