Double-sided magnetic USB cable

Thread Starter

iMagUdspEllr

Joined Apr 20, 2020
2
Tl;dr: I spliced two cables with magnetic connectors together in order to create a cable that has magnetic connectors on both ends. This didn't work. I'm not sure what I'm doing wrong.

I read some articles that inspired me to build a custom USB cable for my keyboard. I thought I would try to do something more ambitious than just put paracord and TechFlex on a USB cable that I assembled myself. I like the idea of using magnetic cables to make the process of plugging and unplugging my keyboard more streamlined. I know that I can buy magnetic cables off the shelf. But, all of them seem to only have one end that is magnetic and the other end is usually USB type A. I thought I would simply cut the Type-A connectors off of the cables, splice the two cables together, and then I would have a double-sided magnetic cable that I desire.

However, this didn't work. I tried to solder red, black, green and white wires to each other; this didn't work. I tried to solder red to black, black to red, green to white, and white to green; this also didn't work. I noticed that these magnetic connectors have an LED. This means I would have one more LED in the cable than it would normally have. My basic knowledge of electronics tells me that diodes only allow current to flow in one direction. But, all of the continuity checks that I have made with my multimeter seem to tell me that everything is flowing properly and I don't have any shorts between the hot and return wires. I seem to have the proper continuity between the appropriate contacts on both connectors. In an unmodified cable, the LED illuminates even when the keyboard is not plugged into the cable.

Would someone please tell me why this doesn't work? It seems like it should be simple.
 

Thread Starter

iMagUdspEllr

Joined Apr 20, 2020
2
USB cables are high frequency pipes. If you don’t do it right you get nasty voltages bouncing around.
Do you mean the data in the green and white wires?

My issue is that I can't even use the cable to power the keyboard let alone use it to successfully use it to transfer information. Isn't it simply 5 VDC through the red and black wires? I don't know why there would be a frequency problem with direct current. Thank you for your help, though. I guess it is more difficult than I thought.
 

djsfantasi

Joined Apr 11, 2010
6,439
A USB cable is more than a straight through cable. At a minimum, there are embedded resistors so that charging voltage and current can be negotiated. Various USB Hosts and Devices use the cable differently, as defined in the full USB specification.

You’ll have to research your Host and Device to see what options if the USB spec it uses. Also, you need to identify if there are any crossovers in your cable. Then wire accordingly. For negotiation.
 
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