I know this has been covered somewhere, but can't find exactly what I am looking for. I am a newbie maker. I am currently making a 4-string CBG from a Tabak wooden box. I am doing a neck-thru and wanting to mix a piezo buzzer with a homemade pickup I made.
The pickup I made is basically two very strong hard-drive magnets wrapped in copper wire (about 600 wraps or so), then placed into a steel Altoids tin I modified to look like a mini-humbucker (will take a pic and post as soon as I can if needed). I don't have any pole pieces in that I was looking for the top of the Altoids tin (bottom depending on your perspective) to be magnetized and act as one flat "pole piece".
I wired it to an input jack, plugged it in to a small Crate amp, and hung it inside an acoustic guitar to try seeing what it would pickup on. It didn't seem to work. So I am wondering if I HAVE to have pole pieces and if I need to redesign my pickup?
My biggest fear is cutting a slot for the pickup in my lid, wiring it up, and then it not work. I'd have to scrap the box then since my single-coil "mini-bucker" and an actual pickup I have from an old Fender are totally different sizes.
Any help would be much appreciated!
Replies
for Paul I suspect those polymer magnets may have the poles somewhere other than you think.
for example, the craft store ceramic disk magnets for making your own refrigerator magnets have the poles to the sides of the disk, not to the faces.
A cheap cracker jack toy compass is all you would need to help you sort that out.
30 gague wire has 1 ohm per foot, 600 winds is probably in the neighborhood of 100 feet, so your multimeter should register about 100 ohms between your hot and earth lead out wires.
I think your problem is " I left one magnet attached to it, removed the plate from the other magnet and just snapped it ontop of the other"
the poles on those magnets are at the ends. Letting them snap together themselves means you have the N of one and the S of the other against each other. the fields are going just between the magnets and not out to your strings.
remove the second magnet, one of these should be enough.
multi-magnet pickups have to have all the N poles pointing the same direction so as to not cancel each other out, which can be hard to force them to do since they tend to repell each other that way.
Stacking magnets shouldn't be a problem. Each magnet has different pole on each side, so stacking a south pole(south on top north on bottom) on top of another south pole would be north on bottom of first attracting to south on top of the other that has north on it's bottom. So result would be S-N-S-N. Effectively becoming one magnet that's the same as a single magnet with South on top and North on bottom.
stacking magnets pole to pole does make a bigger magnet, but these are bar magnets with the poles at the ends stacked side to side. to make it a bigger magnet they need to be end-to-end like linked sausages. stack them side they cancel because they have both a N and a S pole sticking out the same end of the coil.
Gottcha. So would the use of a compass to determine the poles on the sides and then spinning the magnet around to match the side poles work?
Maybe that would work, but it's a lot of trouble using multiple magnets stacked and better off using one magnet that's strong enough. you can always use a strong magnet to strengthen a weaker one, but that takes careful alignment of poles and time.
I've been trying to strengthen some polymer magnets that I've stacked together to make a DeArmond Gold Foil type pickup for a month now. Not working well so far.
You shouldn't need pole pieces, click on link there, I've done exactly the same before and they work great. However the big sheet of steel is said to affect to magnetic field which is why telecaster neck pup etc is covered in a non ferrous cover. Try snapping another magnet on the outside (top) before you cut open the coil to see if it helps like this
http://i950.photobucket.com/albums/ad348/jeflong/2012%2009%20MagicR...
However if failing a continuity test you might need to rewind. Can you get the coil out of the tin, wrap it in tape and put it back?
Here's a pic of what I did. If you have ever seen a hard drive magnet inside a hard drive then you recognize the shape of the back-plate. I left one magnet attached to it, removed the plate from the other magnet and just snapped it ontop of the other. I then wrapped it up with 30 gauge copper wire. The steel case is part of an Altoids box and is insulated with part of a rubber glove.
I got some connectivity tonight, but only along the bottom side of the box, not the top. I pulled it out of the box only to realize that the corners (right next to where it is wired to the input jack) are the only spots I get a signal. It's not doing ANYTHING anywhere else. Those points touch the bottom of the box when seated so it gets a signal (in that I can tap on it with my fingers or a piece of metal). There is still NO sound. :-(
It's possible the wire is wound around the coil the wrong way for it to work lengthwise.
Here is somebody who made a working hard drive magnet pickup: http://www.joebrown.org.uk/wp/?p=1476
This is the same direction/orientation the lipstick tube coil was wound.
The question is, was a lipstick tube magnet oriented through the width or the length? I always assumed it was through the width. Whereas the hard drive magnet appears to be oriented through the length, like a science bar magnet.
You may be able to take your pickup as is, and turn it on end and have it work. So it would be like one giant polepiece from a Strat pickup.
On the other hand, it could be that those "rules" about magnet orientation are for weaker alnico and ceramic magnets and it wouldn't matter which way you oriented a hard drive magnet. I don't have any here to play with, so I can't say for sure.
In general, I suggest getting the pickup working without the cover first, then add the cover and see what happens. You can quickly test the pickup by holding it closely over the strings and plucking the strings.
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