On Friday, 15 April 2022 15:21:27 EDT Peter C. Wallace wrote: > On Fri, 15 Apr 2022, gene heskett wrote: > > Date: Fri, 15 Apr 2022 14:38:03 -0400 > > From: gene heskett <ghesk...@shentel.net> > > Reply-To: "Enhanced Machine Controller (EMC)" > > > > <emc-users@lists.sourceforge.net> > > > > To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> Subject: [Emc-users] For Peter > > Wallace > > > > Hi Peter; > > > > It looks as if the inavailability of the high voltage op-amp I was > > going to use will make me use just a part of the a/d range of a > > 7i76D first 4 inputs. > > > > And, the relative lack of data for the MAP sensor I have two of, > > might be a limitation too. The data is sparse, but what has me > > thinking is the maximum current available at its output is shown as > > .1 milliamp, at full scale which would roughly correspond to around > > 23 psig, or 38 psia, which is what its actually measureing. And I > > want to regulate the pwm to a bank of teeny conpressors that can do > > at least 10 psig, to around 4 or 5 psig. So rangewise its doable. > > > > Since the max output currant is .1 milliamps, and I need to subtract > > ambient pressure from whatever I measure when the conpressors are > > off. > > This isn't super critical and its something I can do in the setup for > > the program. > > > > So my question then is how big a load is the a/d when doing the a/d > > for for a 2 to 3 volt signal from the MAP sensor? > > > > Thanks Peter. > > The 7I76 field input load impedance for you (older) card woud be about > 20K Ohms If you dont need full scale, then a standard op amp buffer > would do. > > I do have a proto 7IA0 you might be able to use. It has 4x 0-3.3V > analog inputs (buffered so basically infinite impedance) free for cost > of shipping, but its a big card so not suitable if you are saving > space
And that box is only for the 7i76D and a modified 5 axis bob. With smal psu's under the boards. Anything bigger is a new box for that whole maryann. This stuff is going to be hid in the driver box, I'm printing the buck mount now, and the compressors dual BTS-7960 is next. Basicly square pads I'll glue down, with pillars to hold the boards off ground contact. With input load that heavy I wonder if I'll wind up measuring the MAP sensors output current. Some additiional math in hal might be needed w/o the op- amp. Dead accurate not required, but repeatability would be nice. The MAP I think is probably typical, its an NXP-MPX4250A. About 5 years old now-a-days. Once I get it built and installed, I might come back for more advice. Thanks Peter, take care and stay well. > > Cheers, Gene Heskett. > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author, 1940) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > > > > > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > . Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
