I was messing around with a USB camera. I wanted to change the cable because is trimmed but as I was cutting it I saw a small thing (image below). As I was trying to cut the casing and see what it has inside I saw a spark. I tried to connect it with another cable but I don't know if I'm gonna damage the camera or the USB port.
What is it and can I connect the camera without it?
I guess you're talking about the ferrite bead:
Source: Wikipedia - Ferrite bead
Its purpose is to prevent interference at high frequencies signals.
It may also work without it and with a cable as short as possible.
A conductive cable acts as an antenna
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Commented
May 22, 2014 at 13:21
It is a ferrite bead and acting as a choke, or very small valued inductor. It is acting on all the conductors of the cable together, so it is blocking common-mode noise from entering or exiting the connected device.
The USB connection will absolutely work fine without the ferrite bead present. USB cables are normally sold without it.
It was likely packaged with your device because the device was found to be emitting EMI, and the cable was determined to be the source of the emission. It was cheaper to add a choke to the cable than to do any additional work on the design of the camera itself.
A single ferrite bead acts as a low-pass filter, but it rolls off at frequencies well above the highest frequency used by USB. Furthermore, the effect is applied only to common-mode signals. The USB data is on a differential pair, and both conductors are passing through the same core, along with the power conductors. So the USB data will see very little effect from the bead, while EMI will be blocked by the bead.
Lots more than you want to know can be found by reading data sheets. Here is some documentation from one maker. Discussion of common mode starts around page 8 in that PDF.
Its a ferrite bead, designed to suppress high frequency noise on the cable.
You can use it without it, but you might get issues with USB data transfer.
It's a ferrite bead choke, which is used to suppress unbalanced high-frequency signals, typically caused by EM interference. It is essentially a form of passive low-pass filter.
Imaging devices such as scanners and cameras often have such filters on their USB cables because otherwise the EM interference from the cable may introduce noise in the sensor and, thus, the stored image. CCD sensors are often quite susceptible to noise.
Bottom line is that, while the USB connection will probably work fine even without the filter, any pictures that you take while connected to the PC may suffer a degree of degradation in quality.
