Wire Recorder Project- some glitches

[kku855]

Hi, my name is Kathy and I'm working on the "Recording on a Wire" project. I'm just starting to make the project when I noticed that there were some parts of the project that I wasn't sure how to do.

1. How much recording wire should I use to loop around the wheel?
2. The picture shows the ferrite core/wire surrounded by some stuff used to hold it hold. How do I construct this and what is its purpose?

Thank you

[jasonzimmerman]

Hi Kathy,

I will attempt to answer your questions as best I can. I also can pass your questions along to some of my colleagues that have done this project, but I likely won't get in touch with them until Monday.

1) The amount of recording wire is pretty flexible - the more you have, the more you will be able to "store." How big are the wheels you are using?
2) Anything will work, the actual equipment shown in the picture is not required. I am not sure if you have access, but a camcorder tripod would work very similarly. It will allow for some adjustibility of the ferrite core, which will be important. Be creative and look around for readily available equipment that will allow you to orient the key components similarly to what the pictures show.

Good luck and feel free to ask more questions.

[kku855]

Should the ferrite core touch the wire?

[staryl13]

Hi!
I'm not an expert in this field, but I think that based on what I've read so far of the experiment, the ferrite core should touch the wire when it is coiled around. Good luck with your project, look forward to hearing more!

[Craig_Bridge]

Should the ferrite core touch the wire?

There are two different "wires" involved in a wire recorder at the "head". One is the magnetic wire on which you are attempting to record information (sound) for later playback. The other is the electrical wire used to create (for record or sense for playback) the electro-magnetic field at the core gap over which the magnetic recording wire passes. I'm calling this electro magnet / gap assembly the "head" (as in "recording head" or "playback head") because this is the jargon that has been used for years in the magnetic recording industry.

The magnetic coupling between the gap and the magnet recording wire is a function of the gap width, the distance between this gap and the recording wire, and the speed at which the recording wire passes.

You will want to have the magnetic recording wire rubbing in contact with the head across the gap as the effectiveness of the energy transfer falls off rapidly with any distance between the gap and the material being magnetized in the case of recording or sensed in the case of playback.

[kku855]

Thank you and I have a couple of other questions
1. Where can I get the ferrite core?
2. I also can't seem to find any magnet wire 34g. Is there anywhere specific that I can find it?
3. People recommend that I buy some old recording wire, but can I just buy some electrical wire?

[Craig_Bridge]

1. Where can I get the ferrite core?
2. I also can't seem to find any magnet wire 34g. Is there anywhere specific that I can find it?
3. People recommend that I buy some old recording wire, but can I just buy some electrical wire?

1. Try putting "ferrite beads" into a search engine. Beware that you want a small one. Many of the ones on the market are large ones for power cord radio frequency suppression and are unsuitable for use as a recording head gap.
2. Again try putting "34 AWG enameled wire" into a search engine.
3. Recording wire (steel or stainless steel) has magnetic properties not present in copper wire so no you need recording wire. You might try steel piano wire if you can't find any true "recording wire". Again, a search engine is probably your best bet for finding the real thing.
Given that you are missing all three key hard to find components for this difficult project, you might want to rethink your project choice if you are under a time crunch.

[kku855]

I'm planning on using piano wire instead of recording wire, but what size diameter should I get? And can I use 30 gauge magnet wire instead? What would be some problems that I should be aware of if I used a 30 instead of 34 gauge wire?

[Craig_Bridge]

I'm planning on using piano wire instead of recording wire, but what size diameter should I get?

As long as it is a single straight steel or stainless steel wire used for the treble notes, its precise diameter probably doesn't matter. I would try two different diameters, a really fine thin one and another between 1.5 and twice the thin one, to see which works best in your design. How stiff the wire is and how easily it unrolls from your source reel and conforms to the head and rolls up on your takeup reel is something you will have to experiment with.

can I use 30 gauge magnet wire instead? What would be some problems that I should be aware of if I used a 30 instead of 34 gauge wire?

The diameter of this wire will affect how many turns you can get through the ferrite. If you can only get the wire through once, you are likely to get somewhere between .2 and .8 effective turns which will reduce the effective coupling of this critical component. Note: this is a variation of .6 turns in an average of .6 turns which means you can't really calculate anything accurately. If you can get two through the center of the ferrite without scraping the enamel insulation, then you will have somewhere between 1.2 and 1.8 effective turns (and the variation is .6 turns difference / 1.6 average turns). If you can get three through the center of the ferrite, then not only are you increasing the magnetic coupling by increasing the turns, you are reducing the variation yet again. Smaller diameter magnet wire will give you more options when it comes to experimenting with heads. Since you are already going to piano wire which wasn't designed to be used for wire recording, you may need more magnetic coupling in the head in order to work. I would personally try for something between 34 AWG and 40 AWG based on what is used in comercially available tape recording heads.

If you are thinking, I can just use a bigger ferrite to get around this, you are mistaken. A larger ferrite will take more electrical power to induce the same magnetic field at the gap and it will be harder to create a narrow uniform gap in. For recording, this can be overcome by using more power; however, you can't do anything for playback except use a better recording medium (ruled out by your choice of piano wire), more turns (ruled out by your choice of magnet wire gauge), smaller gap (skill and tool setup and number of lucky tries will only go so far), better gap contact (again tough to control and this parameter doesn't gain you much once you get close).

[kku855]

If i were to buy just plaine steel wire, what gauge should it be, and about how much of it should i buy?

[Craig_Bridge]

If i were to buy just plaine steel wire, what gauge should it be, and about how much of it should i buy?

I don't know. The guage of the steel wire is not as important as some of its other properties. You want the recording wire to be stiff enough so that it won't easily kink when it is bent around the take up and supply spool/reel and any guides in its path; however, you don't want it too stiff so that it is too springy when it is wound on a spool/reel.

The magnetic properties and gauge (diameter) of the wire, the width of the head gap, and the speed of the recording wire during recording will affect the frequency range that can be recorded. My intuition is that you want the diameter to be at least as large as the head gap width.

As far as how much wire you need, If you try recording at 6 inches per second and you want to record for 30 seconds, you need at least 15 feet plus the length of your wire path plus enough to attach it to the takeup and supply spool/reel.