On Sun, Jan 29, 2017 at 6:48 PM, Gene Heskett <[email protected]> wrote:
> On Sunday 29 January 2017 12:40:21 Alan Corey wrote: > Alan, ALL of the motor drivers are switchmode, with the current > regulation running at or above 20 KHz. And these noise spikes are > ringing at nominally 100 MHz. I have managed to get the xy motor noise > under control by takeing out the switchmode psu's, and putting in > tordoid transformers, bridge rectifiers, and the biggest electrolytic I > had in the drawers that had sufficient withstand voltage. Its a star > ground system, and the output cables to the motors are shielded, and the > shield grounded as it goes by this single bolt ground on its way out of > the box. The shielding extends both ways from that point but is not > connected either at the motor, or at the driver, just at the bolt. This > is std in such noisy machinery. i'm going to be looking at setting up an open hardware lathe and cnc machine at some point, so i'm really delighted to see what you're doing... i'm just really very confused as to why you're using such a low-cost board from a *known* unethical fabless semiconductor company to control such really very expensive equipment. just sayin. anyway: when working for Path Intelligence we learned the hard way about R.F. and EMI interference, so we had to nickel-copper paint the entire interior of the IP66 box and replace its rubber gasket in the lid with a conducting one. we also got a 2nd-hand spectrum analyser, our resident expert made a probe out of a single 20mm loop of copper wire exactly like you see in the fairground attractions in days of yore, and we could confirm immediately the effectiveness of anything that we tried to do. which was really *really* effective in the case of the nickel-copper spray. i can therefore strongly recommend trying the same thing... but honestly, the cost of all this equipment should be far in excess of just replacing the entire board, including the processor that's made by the unethical company known as broadcom, so i have to ask, particularly given that it's so problematic, if you'd given that some thought as a first priority rather than a last? l.
