On Sunday 04 October 2009, Steve Blackmore wrote: >On Fri, 02 Oct 2009 11:34:45 -0500, you wrote: >> I would think a 1 K Ohm >>resistor from +5 V to the A and B would make a big difference. You can >>get +5 V from the game port or a >>hard drive plug. Yup, also looking closer, I see COORDINATED spikes in >>both A and B on a number of >>cycles. That reinforces my suspicion of the above. > >Hi Jon > >Encoder is connected to a couple of UA9637ACP differential line >receivers. I'm putting A+ A-, B+ B-, I+ I- in and getting A, B, I out at >3.5V, should I connect the resistors on the outputs of the line >receiver? > No, or I wouldn't just yet, Steve. I'd put the pullups on the encoder outputs themselves as a first pass, doing it at the much more convenient inputs to the UA9637ACP.
But, I just looked it (the UA9637ACP data sheet) up, and it has what looks like the std TTL output stages. It can pull a 20ma load down to .35 volts (I'd suspect it can do better, much lower), but can only source 1 ma to do the pullup at the output. Based on that I think I'd figure on a 10ma pullup, or a 4.7k low wattage resistor pulling BOTH the inputs from the encoder, and the outputs of the UA9637ACP up to the 5 volt line. That I'd assume is clean but it wouldn't hurt to look at it with the scope anyway. It might need some local bypassing. That would be 15 ea 4.7k 1/8 watt resistors assuming the index inputs are also differential. Per channel you need to fix, but it wouldn't hurt to fix them all just for peace of mind. -- 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) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> We have phasers, I vote we blast 'em! -- Bailey, "The Corbomite Maneuver", stardate 1514.2 ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
