Can I use inductors as pickups?

[sean k]

So I'm doing a reverb using a plastic slinky, driven by a speaker, and instead of doing some windings on alnico or neodenium slugs I'm wondering if some 300-500mH inductors I have will actually act as guitar pickups. Just to clarify I'm going to wind some steel guitar string around the plastic slinky spring to get some Iron moving in space.

I'm just slightly worried that if the inductors have ferrite slugs then they ain't going to be affected to induce a current in the windings if it ain't actual magnetic material in the core and if this is the case is there a material which will induce polarity change in ferrite if it's moved about in it's field.

[R.G.]

A coil of wire produces a voltage in response to a changing magnetic field in the volume of the coil. No magnetic field, no signal. No *change* in the magnetic field, no signal.

An inductor is wound on a bit of ferrite that is specially selected for low remanence; "remanence" is the property that causes ferromagnetic material to retain (remain...) some magnetic field when external forcing fields are removed. So your inductor will not retain enough magnetic field to act as a pickup.

You can fix this by adding a small permanent magnet to one end of the ferrite slug. This magnet then supplied a permanent field that the slug "conducts" and this provides a static field which the moving iron can drag around and cause changes the coil of wire will pick up.

[sean k]

Okay, thanks R.G.!, thats really simple. Just add one of those small buttons of neodenium to the bottom of the inductor. I did read up on ferrires at wikipedia and found the properties of soft and hard ferrite and kinda guessed that inductors involved soft ferrites but the explanations didn't quite give me what I needed to know.

Case in point though is that they are a winding and I shoulda figured that they'd just need a little magnetism added. I made a bass pickup once where the poles were mainly 5mm bright steel rod but I added little neodenium slugs to the ends, below the pickup, and it ended up being a nice pickup for bass.