Typically 0.1 bypass caps REALLY to have to be physically close to the load they are bypassing. Within a few millimeters. Cut the leads short and bridge the power pins with the cap.
Placing a larger cap farther away can't cause any harm but it is not going to do the same job. Reason: The real world is not the same as theory. All caps have an internal series resistance (ESR). Think of them as a cap and resister in series and model them that way too when you design the circuit. The ESR of a .1uF ceramic cap is nearly zero, but for the tantalum, you need to look it up in the data sheet. Why physically close to the load. Wire has non-zero impedance. Mainly in this case it is inductive. You need to minimize the value of the inductor between the 0.1 cap and the device. Apparently the manufacturer wants a low impedance power supply. Draw the circuit schematic with a the lead wire inductance and cap's ESR shown then you can see that needs to be minimized. Don't worry about space you candy 0.1 caps that are the size of a large grain of sand The usual way to mount these is to make a tiny PCB that has the device on to and a mounting hole and the passive parts like the capacitor(s) and a connector for the cable. All that said, it will likely work OK if you can get that small ca reasonably close. Better to get the 0.1 closer then a larger one farther way as the goal is to minimize the amount of wire And using a larger cap is no substitute for the .01 either because I bet the .1 was spec'd mainly for its low ESR, not because it needed to be exactly 0.1uF On Fri, Oct 14, 2016 at 9:51 AM, Gene Heskett <ghesk...@shentel.net> wrote: > Greetings everybody; > > A bit too cold this morning to go out to the shop and saw out the thicker > spacers I am going to need to permanently mount the Z motor and screw > anchor. > > So, not wanting to waste the day waiting for it to warm, I went back to > work on the encoder thing this morning. > > I now have an additional tab of alu extending to the left to hold one of > these ATS667's as an index pulse generator, and have that one s-glued in > a bit beyond where the center of the glued on screw passes by, hoping it > won't trigger on a regular tooth. > > But, I've never used any of these before. No clue as to their bad > habits. > > The spec sheet I have shows a "required" .1 bypass to ground on the VCC > lead, but has anyone had any problems using just one for all 3 devices? > This thing is cramped for space for a bulky mylar .1. > > So I intend to put an even larger tantalum on the pcb, which will be on > the left face of this added tab as I can let it project inward nearly 20 > mm's in that space, lots of space before encountering anything that > moves there. That means I'll have to paste some wrapping wire to extend > the leads about 1" to get to the pcb. So this bypass cap may be as much > as 2" of wire away from the device body. > > Can anyone testify that the extra lead length is a problem? > > Thanks all. > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
