On Friday, January 27, 2012 01:36:21 PM Viesturs Lācis did opine: > 2012/1/27 gene heskett <ghesk...@wdtv.com>: > > Is there perchance an adjustment potentiometer? The LM317T is a > > linear regulator device and could be made adjustable so as to > > compensate for the wiring and switching loss in your controller. > > Nope, I see 2 resistors in series for the middle leg. > > > I'm sorry. I try to describe things in understandable terms and > > obviously I didn't bridge the gap very well. > > I think that You did pretty well, it is just thatI do not get that > pretty well :) > > > That very thin wire will probably need replaced with something heavier > > while maintaining flexibility for long life. Or perhaps the LM317T > > needs turned up a few hundred millivolts. See the sample schematic > > shown here: > > > > <http://www.national.com/mpf/LM/LM317.html#Overview> > > > > Perhaps the maker used a fixed resistor in place of R2, the adjustable > > one? Given parts tolerances it could already be borderline low. > > Given that 20-100 millisecond response time probably won't be a show > > stopper, another thought that may be easier for you to fab on site > > would be to use your controller circuit to switch a relay. That, and > > heavier wire might be the better method as opposed to turning the > > supply up .250 additional volts because someone may replace a future > > broken cable with an even heavier one which would let the magic smoke > > out of the laser. > > I looked carefully and it looks to me that there are 2 resistors in > series, where is R1 in that scheme and that connection to GND through > R2 - I do not see that.
Could be hidden by a via thru the board I suppose. But see below. > Ok, I think I have to explain one thing that was missed and seems to > be misunderstood: > I do not want to detach laser board from the laser itself - they are > connected with ~40cm of wire and I would like to keep it that way. My mistake, I was under the impression the psu was a separate item that could have been frame mounted several meters away. > That thin wire is between my diy driver and the laser board. > So I will try to figure out, how to replace the wire. That depends. Can, if you just short your device, burn wood? If not, or only very much slower than you expected, then the wire is too small. However, this gives me another better idea, that of putting your DIY switching device right at the laser, essentially doing away with the wiring losses, and use the existing small wire going to it for the logic signal to control it. That seems like the most serviceable solution to me, quit trying to send the amps up and down a small wire, just send the controlling signal. I am assuming that the relatively small currents your DIY needs can be supplied by the lasers own supply, removing the need to also send your DIY a pair of power leads of its own. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> We have only two things to worry about: That things will never get back to normal, and that they already have. ------------------------------------------------------------------------------ Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
