On Fri, 2012-01-27 at 16:55 +0200, Viesturs Lācis wrote: > 2012/1/26 Kirk Wallace <kwall...@wallacecompany.com>: > > On Thu, 2012-01-26 at 08:40 +0200, Viesturs Lācis wrote: > > > > An off-the-shelf solid state relay might do the job too. > > The relay was my first idea, but it turned out pretty quickly that > there are no such relays that could be driven directly by Mesa card - > even those with 5V coils on control side would require too much > current for gpio pin to sink - I think that smallest I found was > around 100 mA.
Solid state relays generally have an opto-isolator built in, with the same LED input, so only require a few milliamps to turn on. For instance: http://search.digikey.com/us/en/products/DC60S3/CC1126-ND/221844 http://www.crydom.com/en/Tech/crydom_us.pdf http://en.wikipedia.org/wiki/Solid_state_relay A couple of things to note, ssr's don't turn OFF all the way, they have a very slight leakage, which mechanical relays don't do since the contacts are separated by air. Also, it is temping to use AC ssr's with a DC load, but this won't work because the AC relays need the AC zero crossing in order to switch OFF. > I just wanted to tell that I resoldered optoisolator and now it is > kind of working correctly. > Laser is shining. > The problem is that it is not burning the wood. > Is the voltage drop in the wiring too high? > How can I help there - use thicker wire leads? > > Viesturs Measure the voltage at the laser with a meter across the "GND" and "dc 9 - 12 volt" terminals. If it dips below 9 Volts you most likely need to find a way to bring the voltage up. It apears the laser needs only 1.3 Amps so any decently sized wire should work fine. Check to make sure the TTL terminal comes up to TTL voltage level, maybe between 3 and 5 Volts. I believe LinuxCNC should feed this pin with a 20kHz PWM or PDM signal to control the laser's output strength. Also check to make sure the laser can focus on the target. -- 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
