You are going to have to post a schematic. But the use of a 2n7000 kind of calls attention. The 2N7000 is a very low power device. Some older designs might use a 2n7000 to control a larger MOSFET but today we have larger MOSFETS that can be directly controlled by logic-level signals so we don't have to design gate drivers. Post a schematic and people will see better what you are doing.
Also, you do not say what kind of motor this is. If it is a smallish DC motor the more common way to control direction and speed is with a dual h-bridge. Not a relay. You can buy these cheap with logic-level controls. On Sat, May 9, 2020 at 4:53 AM Dan Henderson <[email protected]> wrote: > > Good morning Gents— and I use that term loosely ;) > > I’m trying to test out the basic premise of a reversing circuit. I’ve got a > breadboard on the table here and I’m attempting to send a CCW signal from > the BOB to a mosfet gating chip (2n7000) middle leg. It’s used to switch on > the relay coil which in turn activates the DPDT switch of the relay. It no > workie. The relay coil requires 12 Vdc. I have a diode between pins a and > b of the coil otherwise it would immediately actuate the contacter. In > theory this setup should work. I measured output voltage of the CCW pin @ > 4.8 vdc high and when on an M3 it drops to .387 vdc. Essentially the mosfet > holds the ground captive until the middle leg receives a signal (CCW) then > it allows the ground to “source” and the relay should go “click”. > > Not sure if any of this makes sense, it barely makes sense to me but the > circuit was designed by an expert so I’m not going to question that, maybe > my implementation. > > > On Sat, May 9, 2020 at 1:15 AM John Dammeyer <[email protected]> wrote: > > > One of the greats in computer science has a series of interesting quotes. > > https://www.azquotes.com/author/15849-Niklaus_Wirth > > > > One I really like is: > > "The belief that complex systems require armies of designers and > > programmers is wrong. A system that is not understood in its entirety, or > > at least to a significant degree of detail by a single individual, should > > probably not be built." ~ Niklaus Wirth > > > > I often wonder if LinuxCNC has reached this point. > > > > Although so far, Andy Pugh appears to be that single individual so I may > > well be wrong. > > > > John Dammeyer > > > > > > > -----Original Message----- > > > From: Gene Heskett [mailto:[email protected]] > > > Sent: May-08-20 9:44 PM > > > To: [email protected] > > > Subject: Re: [Emc-users] Fluctuating RPM using CUI ATM 10 encoder > > > > > > On Friday 08 May 2020 22:36:35 Dan Henderson wrote: > > > > > > > Thanks for the examples. I'm not going to lie, I've got some homework > > > > to do on this. You guy's make this sound easy but to the new guy > > > > looking in? No so much, lol > > > > > > Don't be glum Dan, you've already demo'd to me that you WILL get there. > > > > > > The fact that LinuxCNC is being further developed, literally as I type > > > this, even if the basic premise is decades old, can't be emphasized > > > enough. One of the reasons I posted snips of my old code, old but still > > > after the new words were added to the hal recipe, was to demo that, far > > > more than any finger pointing at Jon's example. If it works, its right. > > > > > > I apologize to Jon if it was taken that way. > > > > > > I cannot today even run that code, because the hardware under it has > > > changed. For the better is an arguable point because that driver Jon > > > makes is a no compromise device doing exactly what you tell it to do > > > with zero drama. It can now make that same motor break all sorts of > > > stuff between it and the chuck it spins if I hadn't taken measures to > > > tame the violent acceleration that drive is capable of making it do. > > > OTOH, that 1 hp rated motor can now deliver nearly 2hp because the psu I > > > built out of junk box parts makes 35 more volts and 10x the current that > > > cleared the fuse in the OEM configuration. But it also gets the job > > > done. Its had stuff in that 5" chuck that weigh half what that whole > > > lathe weighs, and made the part. > > > > > > [...] > > > > > > > > Yes, I'm pretty sure it still does. But, yes, this is OLD > > > > > STYLE hal code, for sure. > > > > > You can combine any newsig / linkps / linksp into one net > > > > > command, with > > > > > > > > > > net signal-name pin pin pin ... > > > > > > > > > > And, you don't have to tell it the signal type, it gets it > > > > > from the first pin. > > > > > > > > > > Jon > > > > > > > > > > > > > > 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) > > > If we desire respect for the law, we must first make the law respectable. > > > - Louis D. Brandeis > > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > [email protected] > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
