Mac GUI

Re: Apple II to 4-20ma

comp.sys.apple2

Author: Michael J. Mahon
Date: 22 Jul 2014 11:25 pm
Ref: 1

Smohn Jith <Smohn@smohn.com> wrote:
> Is there a simple way to get the Apple II to output a 4-20ma industrial
> control signal?  I've looked at some of the Arduino and Pi stuff, but I'm
> not sure/savvy as to whether they would work off the gameport or
> something else.  Any ideas?

Do you only need digital output (just two states), or do you need
continuous control (analog) over the 4-20ma range?

Digital is easy, and can be done with an annunciator output, an emitter
follower, and a current limiting resistor.  

Analog is also possible, but will require either a hardware D/A converter
or, if the Apple can be monopolized during signal generation, a software
DAC (for relatively slowly changing signals).  

If you need analog, what resolution and bandwidth do you require?
--  
-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon




Apple II to 4-20ma
122 Jul 2014 9:38 pmSmohn Jith
222 Jul 2014 10:04 pm|- mwillegal
324 Jul 2014 3:51 am|  \ Smohn Jith
422 Jul 2014 11:25 pm\ Michael J. Mahon
524 Jul 2014 3:50 am   \ Smohn Jith
624 Jul 2014 4:08 am      \ Michael J. Mahon