Re: missed keystrokes problem, back with a vengeance.
On Sun, Jan 29, 2017 at 01:48:50PM -0500, Gene Heskett 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.
Well the USB would probably be at either 12MHz (USB 1.x) or 480MHz (for
USB 2), but most likely USB1 for your keyboard. That certainly is a
potential place to hit with noise if you are getting spikes into the
100MHz range. And USB cables don't appear to be that well shielded in
general (they seem to aim for cheap).
--
Len Sorensen
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