Kill GSM radio buzz with $1 ferrite beads
Ever noticed a cylindrical bulge on USB cables? It's a ferrite bead, designed to dampen high frequency radio noise. Michael Simon of Mac|Life finds that they help cut GSM babble, too, preventing his desktop speakers making those weird buzzing noises when he leaves his cell phone next to them.
It’s really quite simple. Take a pair of scissors and cut off the end of the USB cable. Pop open the ferrite case and slide the bead off. Then, all you need to do us attach the bead to the end of your speaker cable, where it meets the speaker. If you cannot fit the connector through the pre-drilled hole (I couldn’t), simply tape it to the wire with a measure of electrical tape.
Or maybe just buy one for a buck.
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Actually, that's buying 4 for a buck.
Curses! You made me look at Electronics Goldmine! I'm going to end up with a bunch of stepper motors, a pack of push-button switches, assorted integrated circuits and a box of nearly-new solar cells.
Again.
These are nothing new. We used to have them designed into products as a routine. In my past I have installed countless retrofits using these split beads. Many times as FCC compliance or reliability enhancements. Other times as " It malfunctions horridly before the ferrites go on. The commonality of RFI producing devices approaches ubiquity these days. So making anything not inherently robustly immune to RFI is questionable logic at minimum. Here's my short take on why.
The cost of proper design and a few fractional cents per device is unlikely to equal,let alone exceed that of recalls.And truck roll required campaigns in this fuel crisis economy are a new plague.. As they could wipe out profitability in a low margin venture!
Let's just say that Muntzing may have made sense with gas under 50 cents a gallon but as gas approaches $5/gallon that trip back to tweak something or add ferrites as in this case could kill your profits fast. I suspect that the bean counters or in this case BEAD counters may be costing more than they save here.
I just looked at the 20 or of these I have around, and 90% of them were able to be removed without ruining the end of a cable. Just look for separation tabs.
You can get clip on ferrite beads so you don't have to ruin anything.
http://www.dansdata.com/images/io022/beads560.jpg
Used on stuff inside your pc, among other things. Can often solve expensive seeming problems amazingly easily.
So go get more expensive ferrite beads and enjoy.
You're welcome :)
I use these things by the handful. It's much tougher to keep 50 watts of RF out of your speaker system than the fraction of a watt that your GSM phone puts out! I had about half a pound of them on my cheap PC speakers before I got rid of most of the interference.
Not sure if I'll get in trouble for a blatant commercial plug or not, but I've got clip-on ferrites for a good price in low quantities with cheap shipping in my own store:
https://www.argentdata.com/catalog/product_info.php?products_id=44
I use them on smaller cables by wrapping two or more loops through the clamp.
For larger quantities, Digi-Key has good prices on these, too.
Doesn't work. I debunked this along with some other viral marketing myths in this video: http://www.ifonenation.com/2008/06/26/soda-can-iphone-radio-interference-shield-busted-as-a-hoax/
#6 - I don't think that really counts as rigorous testing. First, did you establish that your problem was RFI coming in the cable? It could be getting directly into the speaker (or rather the speaker's amplifier circuit) at that range.
Ferrite beads most certainly DO work for their intended purpose. As #2 pointed out, lots of gadgets would never meet EMC requirements without them. I design them (little SMT chip versions) into my own devices whenever possible. You can read the specifications and see exactly what the attenuation should be at a given frequency.
I'd be interested in how much noise got into that speaker with the audio cable completely removed. If that *does* eliminate the problem, then ferrite beads probably can help if properly applied. Make sure you get one that fits fairly tightly against the cable, because it won't do much good if it's not actually in close proximity. Try moving it along the cable, and maybe add another at the other end.
#6 - Soda cans =/= ferrite beads. Also, this isn't "viral marketing," it's proven science.
About the only thing debunked by Ghengisphlip is his supposed understanding of proper test procedures and the scientific method!