Electromagnetic fields are present everywhere in our environment but are invisible and silent respectively to the human eye and ear. As you probably know, Electric fields are created by differences in voltage: the higher the voltage, the stronger will be the resultant field. Magnetic fields are created when electric current flows: the greater the current, the stronger the magnetic field..
So any electrical source generate a time-varying magnetic field that is proportionally identical in frequencies and amplitudes to the source. This is the theory behind all the speakers, dynamic microphones and also guitar pickups.
The Seymour Duncan pickup has a better Signal-Noise ratio and almost doesn’t make any hum because of his twin coil design. Soldering the white one is very easy but you’ll need wiring instructions if you plan to get a Seymour Duncan.
- Electric Sources:
Those are a few examples only. Because pick-ups don’t need any power, I soldered an XLR to 1/8 inch cable so that I can hook them up to my Sony D-50 and carry it in my pocket. I usually throw them anywhere I see an interesting source of energy (engine compartment of a car, photocopier, transformers, electric poles, network routers and links etc…). You can listen to the signal made by your remote when you press a key, your camera adjusting the lenses or the flash loading, a spinning hard-drive or the sound of your RAM writing data in your computer, a satellite antenna etc…
One of the biggest advantage of this technique is that it is not sensitive to wind, handling noise and background environment. But it’s sometimes harder than you think to isolate a big hum generated by the AC when you’re focused on the servo of a printer. I’ve destroyed my cellphone and froze the RAM of my laptop though, so please read the caution below before starting any experiments.
Powerful magnets can affect the operation of pacemakers and other similar medical devices. A guitar pick-up must never be placed near a person with such a device. Powerful magnets can also damage electronic devices such as TVs and CRTs. They may also scramble data on magnetic media such as hard disks, credit cards, ID cards and cassette tapes.
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