beginning with pickups (a few questions from someone just starting)

[haroldland]

hi -
i am a guitar player that has become very interested in pickups - they seem to be quite important and quite expensive and i'm curious to get a sense of what can be done with them.

i recently watched this video of someone assembling a pickup from junk materials, which got me thinking that maybe i could make my own:
https://hackaday.com/2019/04/14/buil...up-from-scrap/

at the moment, i don't have any neodymium magnets, but i do have some ferrite cores. i am wondering if wrapping a thin gauge magnetic wire around a ferrite core many times would function as a kind of pickup.

after watching a number of videos, it seems that there is a great deal of sensitivity related to the number of winds and the tightness of the winding - but what i don't understand is the relationship between a densely-wound pickup and the output result. is there more hum? better frequency response? a wider magnetic field?

finally, i'm curious about the difference between a guitar pickup and a tape head. it seems like i can play sound through a tape head and a guitar pickup will amplify it, but i can't hear actual tape when i run it across a guitar pickup. what would have to change in a guitar pickup to play back magnetic tape?

[big_teee]

There is lots of pickup info on youtube, and all over the web, and on our forum here.
https://www.youtube.com/results?sear...+guitar+pickup
Most guitar pickups use alinco magnets.
Some use Ceramic magnets.
If someone else has anything to add, please do.
GL,
T

[Mick Bailey]

The pickup in the link has none of the attributes that are needed for decent guitar pickup. There's a huge gulf between something that will produce a sound and something you'd fit to a guitar and be happy with. Don't confuse a regular ferrite core that is non-magnetic with a ferrite (sometimes called ceramic) magnet. You need permanent magnets for a pickup, otherwise there will be no output. The wire gauge needed for a regular pickup is thin and easily broken and due to the number of turns required it's not feasible to wind by hand. A simple pickup winder can be made quite cheaply and maybe a starting point would be to build a winder and get hold of a cheap or scrap single coil pickup with individual slug magnets, cut off the windings (making a note of the winding direction) and rewind it yourself. A Strat-type pickup is probably the most straightforward.

The number of turns affects the output level but there are many more aspects to this. More turns means more capacitance, more resistance and higher inductance (amongst other things). This affects the frequency response. Also, more turns equals higher impedance and more noise. There are low-impedance pickups with heavier gauge wire and fewer turns, but these are not common.

The difference between a guitar pickup and a tape head? A guitar pickup has magnetic pole pieces and senses an unmagnetised string. For tape playback the head isn't magnetised and senses a magnetic tape (effectively the reverse operation). If you pass a magnetic tape across a guitar pickup it erases the tape as it passes. In fact early tape echo units used a permanent magnet to erase the tape - you cannot change a guitar pickup to play back magnetic tape. A tape head also as a very narrow gap of just a few microns to sense where the magnetic tape passes. The guitar pickup has a broad magnetic field to pick up the string vibration and to ensure that when a string is bent it doesn't fall outside of the field. A tape head on 'play' in proximity to a guitar pickup interacts with the pickup's magnetic field and that's why you hear it.