On 01/27/2012 11:07 AM, Viesturs Lācis wrote: > 2012/1/27 gene heskett<ghesk...@wdtv.com>: >> >> 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. > > I could. Now it seems that my diy stopped working again - laser > receives ~3V DC regardless of the state of gpio output pin. > > I give up trying to get it working. > >> 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. > > Thanks, sounds like a pretty good idea. Its only downside - I cannot > implement it on the spot at client's site, because I have to redo my > diy - it is on the same piece of pcb with 7 input optoisolators for > home, limits and e-stop. > > 2012/1/27 gene heskett<ghesk...@wdtv.com>: >> On Friday, January 27, 2012 01:50:53 PM Kirk Wallace did opine: >> >>> I suspect the power to the laser driver just needs to be switched as an >>> Enable, with the driver's TTL input modulated by PWM/PDM to turn the >>> bean on and control the strength. >>> >>> I have zero experience with lasers, so grains of salt are recommended. >> >> And I suspect you are spot on, and that we have managed to make a larger >> problem out of it than it is. >> > > As I wrote - there are only 2 connection terminals for laser board, > labeled "+" and "-" > > Viesturs
Of course that won't work with most if not all the suggestions I've seen so far. If I understand it correctly, your "laser" already has a circuit to drive it at reasonable current to do it's magic. Circuit I suggested earlier was under assumption you have a bare laser diode connected to it. You cannot daisy chain circuits one after another and expect laser to work properly. Relays are out of question IMO because they are too slow mechanical devices with many other drawbacks for this application. I see no reason to bring in solid state relays into the picture either. You are not driving high voltage stuff. You either need to modify your PCB that came with the laser diode or build a new circuit. Maybe you can reverse engineer that PCB and use one spot to inject signal from the EMC side. This link would be a good starting point to get an idea what you are dealing with: http://www.rog8811.com/laserdriver.htm Suggested circuit uses same IC regulator LM317 as you mention having in currently included PCB I believe. Links that might help: http://laserboy.org/ http://repairfaq.cis.upenn.edu/sam/laserssl.htm#ssltoc You are practically dealing with the same issue as power LEDs except that laser diode provides coherent light: http://www.instructables.com/id/Power-LED-s---simplest-light-with-constant-current/ -- Rafael ------------------------------------------------------------------------------ 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
