On Fri, 2012-01-27 at 21:18 -0500, Ed Nisley wrote: ... snip > At the risk of sounding like an Olde Farte, the easiest way to get this > contraption working is a small mechanical relay: a few tens of mA in > will switch an amp of DC on the output. No voltage drops, no muss, no > fuss. > > The optoisolator won't have enough current capacity for the relay, so > you will probably need the driver transistor to power the *relay* from > the digital output. But there's no need for the optoisolator in that > case. > > Or, of course, I could be completely wrong... >
Mechanical relays aren't sexy but they do have advantages in some applications. They don't have leakage current and I believe someone on this list mentioned that certain types are required for emergency disconnects. I know nothing of laser CNC's, but I get the impression that it would be very desirable to be able to turn the beam on and off _very_ quickly, say for making dotted tear lines in foam or paper sheets, or for engraving small letters into metal parts and such. I don't know if the driver power input can be used for this purpose. It seems a laser driver with a modulation input would be preferred. My plan would be to setup a mechanical or solid state relay to turn the laser ON with HAL's machine ON, then run the TTL modulation input to a Mesa pin. This thread informative, but now I feel the need to build one. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
