USB communication cord

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Jbenny509
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USB communication cord

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My monport had come with a USB cord that is used between my laptop and laser. The cord has some sort of a round block attached to it and I think it's some sort of filter. Can I replace that cord with a standard USB cord or will it need that block on it? Sorry for the picture turned 90 degrees, not sure what happened there.
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Jim from Tulsa, OK. I have a monoport 100w and I also regrettably own an eX-Tool D1 Pro, 20W. I've been using lasers since 2021
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Re: USB communication cord

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The block is a ferrite core and its purpose is to prevent interference from that cord from getting OUT to other devices such as phones or audio equipment so yes, you should be able to replace it with a USB cable that doesn't have one.
My name is Marty. Started this hobby Dec. 2022. Using Roly LaserMATIC10 with Lightburn on Windows.

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Re: USB communication cord

Post by Jbenny509 »

martinmarty wrote: Fri Oct 04, 2024 10:23 am The block is a ferrite core and its purpose is to prevent interference from that cord from getting OUT to other devices such as phones or audio equipment so yes, you should be able to replace it with a USB cable that doesn't have one.

Thank you so much!
Jim from Tulsa, OK. I have a monoport 100w and I also regrettably own an eX-Tool D1 Pro, 20W. I've been using lasers since 2021
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Re: USB communication cord

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martinmarty wrote: Fri Oct 04, 2024 10:23 am The block is a ferrite core and its purpose is to prevent interference from that cord from getting OUT to other devices such as phones or audio equipment
Short version: the ferrite bead has no effect on the data signals. Interference from external sources such as AC power lines and radio stations are greatly reduced in amplitude, eliminating their effect.

Long version:
A single wire will act as an antenna, picking up radio stations and AC hum from power lines. Even if the cable has a shield in the form of a wire mesh around the wire carrying the signal it will still pick up interference as the shielding isn't 100%. The longer the cable is the more garbage you end up with.

A USB cable uses a pair of wires per signal. One wire carries the original positive signal and the other carries the same signal with the polarity inverted. At the other end of the cable the inverted signal is inverted again to make it positive and then added to the positive signal. You end up with a positive signal 2x the amplitude of the original. This method is called Balanced Line.

Here's the fun part. If the cable picks up a nearby radio station or AC from power lines this will induce a current with the same polarity into both of the wires. When one signal is inverted and added to the other they cancel each other out, zero current. This is called Common Mode Rejection. The ferrite bead has no effect on the original signal because the magnetic fields of the two wires cancel each other out. OTOH, the common mode interference "sees" the full inductance of the ferrite bead and is greatly reduced in amplitude.

A microphone cable works on the same principle except that it adds a third "ground" wire and the shielding braid is connected to chassis ground. You can run a mike cable over a hundred feet with no hint of AC hum. This is as "noiseless" as it gets.
so yes, you should be able to replace it with a USB cable that doesn't have one.
Sadly, it isn't that simple. There are questionable devices with flakey USB and the bead may make it just barely usable. I have a $1K slide scanner that came with a 3' cable with a big bead on it. Tech support says not to use any other cable.

This is just off the top of my head. No doubt I left something out. :D
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Re: USB communication cord

Post by martinmarty »

MacDoktor wrote: Tue Oct 15, 2024 4:04 pm ...
This is just off the top of my head. No doubt I left something out. :D
Oh, please, continue. I'm not quite in a coma yet. :lol:

I've never had a problem replacing those cables but I concede that if some engineer decided to ship the machine with that cable he might have felt it beneficial.

... and it isn't what Jim asked but I can't help but notice an Ethernet port in the picture which might be an even better way to go if there's a network connection available.
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Re: USB communication cord

Post by MacDoktor »

martinmarty wrote: Thu Oct 17, 2024 6:52 pm Oh, please, continue. I'm not quite in a coma yet. :lol:
That really was terrible but I just couldn't help myself. :D

Here's a diagram if that helps. This example shows how it works for a microphone cable:

balanced-wiring.jpg

Note the plus and minus signs on the triangle. The latter indicates that the signal on that input will be subtracted from the signal at the positive input. It's is hard to explain but once you get it it makes all the sense in the world.

I've never had a problem replacing those cables but I concede that if some engineer decided to ship the machine with that cable he might have felt it beneficial.
More like tech support is sick of having to deal with phone calls from angry customers.

... and it isn't what Jim asked but I can't help but notice an Ethernet port in the picture which might be an even better way to go if there's a network connection available.
The key here is the word "if". And I'm notorious for hijacking topics. :geek:
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Re: USB communication cord

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I use an Apple MacBook so I only have the small USB-C ports and I wanted to use a cord that didn't require that big USB adaptor. I did try using a high quality USB to USB-C cord and there is zero communication between the laser and computer. I really need to get a back up in case something goes wrong with the current cord.
Jim from Tulsa, OK. I have a monoport 100w and I also regrettably own an eX-Tool D1 Pro, 20W. I've been using lasers since 2021
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