Quadrature decoder
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From: mickgeyver on 1 Jun 2010 21:02 On Jun 1, 12:52 pm, zekfr...(a)zekfrivolous.com (GregS) wrote: > Been searching all morning for one, and did find one by LSI/ LS7184. > > I have been looking at a drawing of one from the mid 70's, drawn up by > a coworker who is long gone. > using 74121;'s and 7400. > > I got a sample request, but I think i can do this myself quickly. I got stepper motors > and controllers requiring step and direction input. > Good thing I have this diagram because I can't find others. > Must be some other stuff around ?? > > I don't need indexing or counters. > I also see optical encoders that have the outputs I need for the controllers. > But I need something fast. > > greg If you are planning to use the quad decoder to feed into the stepper motor controller why not just beef up the output drive of your quadrature knob and drive the motor directly? regards, al
From: GregS on 2 Jun 2010 09:42 In article <36b5e8c2-ab41-4657-907f-818f39f2227b(a)v37g2000vbv.googlegroups.com>, mickgeyver <eyezkubed(a)yahoo.com> wrote: >On Jun 1, 12:52=A0pm, zekfr...(a)zekfrivolous.com (GregS) wrote: >> Been searching all morning for one, and did find one by LSI/ LS7184. >> >> I have been looking at a drawing of one from the mid 70's, drawn up by >> a coworker who is long gone. >> using =A074121;'s and 7400. >> >> I got a sample request, but I think i can do this myself quickly. I got s= >tepper motors >> and controllers requiring step and direction input. >> Good thing I have this diagram because I can't find others. >> Must be some other stuff around ?? >> >> I don't need indexing or counters. >> I also see optical encoders that have the outputs I need for the controll= >ers. >> But I need something fast. >> >> greg > >If you are planning to use the quad decoder to feed into the stepper >motor controller >why not just beef up the output drive of your quadrature knob and >drive the motor directly? >regards, >al Well, I liked the idea of having current control, and I allready had one channel wired up. I DO have a driver chip that will do what you said. I am going to consider it for simplicity. Darn stepper is only 3.3 ohoms. greg
From: Ian Bell on 3 Jun 2010 04:51
On 01/06/10 18:36, langwadt(a)fonz.dk wrote: > On 1 Jun., 18:52, zekfr...(a)zekfrivolous.com (GregS) wrote: >> Been searching all morning for one, and did find one by LSI/ LS7184. >> >> I have been looking at a drawing of one from the mid 70's, drawn up by >> a coworker who is long gone. >> using 74121;'s and 7400. >> >> I got a sample request, but I think i can do this myself quickly. I got stepper motors >> and controllers requiring step and direction input. >> Good thing I have this diagram because I can't find others. >> Must be some other stuff around ?? >> >> I don't need indexing or counters. >> I also see optical encoders that have the outputs I need for the controllers. >> But I need something fast. >> >> greg > > http://groups.google.dk/group/sci.electronics.design/msg/8b9bba503375d924?hl=da&dmode=source > > -Lasse The problem with all clocked or sampled quadrature decoded such as those referenced above is transition jitter. I know this from personal experience where such a detector on a mechanical system was subject to vibrations that could occasional cause a rapid set of transition forward&backwards some of which would be missed by a clocked system. This leads to false counts. Cheers ian |