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Has electrical interference been a problem?

Posted: Sat Sep 07, 2013 3:27 pm
by vile_fly
Hi guys, just got my rostock max together last week, and it is working perfectly.
I noticed on other threads that people were having problems with EMI from the motors causing problems. My Rostock is 2nd generation (bought in August) and has none of these problems. One thing I did differently than most was to twist ALL my wires every time I installed something electrical. In my field of work (automotive repair, 20yrs) I learned that twisting the wires together prevents EMI from messing with the inputs/outputs of the computer in a rather severe operating environment. This is proven beyond a shadow of a doubt, since many engineers have been designing/refining these cars for years, and I can't shoot down the laws of physics.
My rostock kit DID come with shielded 4 conductor wire for hookup, but technically, I didn't need it to prevent interference. I used it anyways, since I was paranoid about EMI. Every sensitive system on a car's electronics has been cheaply fixed by simply twisting the wires to both the injectors and to the reluctor-type sensors. The early fuel injected cars had an interference problem induced by the fast switching of the injectors and having all the wires bundled together.....that was the early 80s. Those were recalled rather quickly, since radio towers would kill the engine if you passed too close to them.
Besides...twisting the wires made them easy to feed and just looks neater.
Say goodbye to your ferrite beads.

Re: Has electrical interference been a problem?

Posted: Sat Sep 07, 2013 3:53 pm
by Eric
No argument here. Twisted pairs is better than not. Shielding on top of that is even better. I happen to have a box full of old serial cables from a generation ago that are both twisted and shielded. Some of them are 50+ feet long....great donor wire.

Re: Has electrical interference been a problem?

Posted: Tue Sep 10, 2013 6:14 am
by 626Pilot
Braiding straight wire turns it from an antenna into a much less efficient antenna. I looked up how to braid 4-conductor wire and did that on all my stepper motors. Funny what you say about EMI. I noticed my engine hesitating a little when I was starting it up in this one really EM-heavy spot near some radio transmitters, but it still sparked up. When I had parked there, my media player responded by displaying some unusual characters and then shutting off. It was shielded, too!

Ethernet cable is twisted in the same way, and each pair is twisted at different lengths to counteract crosstalk. It works so well that you can transmit 1 megabit per second over mediocre Cat-5 wire over dozens of meters, and it will work!

Re: Has electrical interference been a problem?

Posted: Tue Sep 10, 2013 12:45 pm
by lordbinky
I had a corgi and she loved Cat.5 cable, so I have a few hundred feet of various lengths that haven't been cut and re-crimped that are useful for spare wires.