Hi Gene, I'm using the same drivers and found a data sheet from www.motioncontrolproducts.com . The type their is MDS542-V2.0. It's the same but tree times more expensive then the China version. You find their also a specification for the resistors when you are using 12V or even 24V.
As long as you keep the current of the LED below 30mA you are on the save side. Though, I didn't worry to much, when I built my electronics for the stepper together, about the current and voltage as I was using 5V. Hoping to be helpful. Regards Peter -----Ursprüngliche Nachricht----- Von: gene heskett [mailto:[email protected]] Gesendet: Dienstag, 27. März 2012 13:23 An: [email protected] Betreff: Re: [Emc-users] Q re opto isolators On Tuesday, March 27, 2012 07:07:43 AM Kirk Wallace did opine: > On Tue, 2012-03-27 at 01:46 -0400, gene heskett wrote: > > What do we normally assume to be the fwd drop of the usual LED, I > > assume IR, opto-isolated input? > > > > Setting up stuff for the 2M542's target 10 ma thru its input opto's, > > I come up with about 360 ohms for the current limiter R when the 5 > > volts is 5.27, and the diode drop is nominally 1.6 volts. > > > > My old meter seems to have taken a hit, and my new one doesn't have > > the beans to measure a diode with more than about .85 volts for its > > band gap, so the diodes in the 2M542 are measuring either .75 volts > > if reverse biased, or open when conventional 'led' bias polarity is > > applied. To say I am a bit disappointed is an understatement, it is > > a $120 meter with all sorts of bells and whistles! > > > > Thanks guys. > > > > Cheers, Gene > > The manual I found here: > http://www.scribd.com/doc/47247471/2M542-Manual > Thanks Kirk. > says at the bottom of page 6, that 5 Volts can be applied to the > inputs without a limit resistor, unless I'm missing something. Maybe > there is already a limit resistor inside. I suppose I'd just add a > resistor and guess at a conservative limit resistance, measure the > voltage across the resistor to see what kind of current is is going > through it when the signal is On. Then reduce the resistance until you > get your 10ma. But that's just me. I can set the voltage from that LM317-T down some, 5.29 volts ATM. Looks as it it should be happy without any limiters if I set it down to 4.9 or so. I have a copy of that printed out in the mills binders and I don't recall seeing that note about the 270 ohm builtins before, so either it has been added or I forgot. In the mills setup, I believe I used 180 ohms which still gave over 10 mills. It seems to be happy. I hesitated to check with this new meter since its 5+ seconds settling time is more than long enough to kill something if its too high. 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> The best portion of a good man's life, his little, nameless, unremembered acts of kindness and love. -- Wordsworth ---------------------------------------------------------------------------- -- This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
