What Size Ferret Core for Magnetic ?

[Airfeed143]

Does anyone know what size the ferrite bead core is on the magnetic wire recorder? It does not say... Also, where would you recommend that you can find these for sale? I've looked at Radio Shack but they don't seem to have them. Thanks for anyone who may reply!

[Airfeed143]

Sorry, for got to ask another thing. I tried looking for the answer to this question on the internet, yet was unsuccessful . Is hookup wire the same as regular electrical wire, or is there a difference? Thanks again.

[deleted-71588]

BEWARE: This is an ambitious project for doing in less than a month!

What grade are you in and what kinds of test equipment do you have access to?

Does anyone know what size the ferrite bead core is on the magnetic wire recorder?

You need it big enough so that the recording wire won't slip off of it; however, you need it small enough so that the inductance doesn't cause issues with your frequency response.

I did a quick search and found http://www.palomar-engineers.com/Ferrit ... beads.html I'll refer to parts on this page so we both are looking at the same specifications. This is NOT an endorsement of this manufacturer nor is it any statement about the suitability of any of these for this project. This was just the first one that the search engine found.

FB-7, FB-18, FB-63, FB-56, and FB-102 are too big.

These come in several ferrite mixtures which are designed for various EMI (Electro Magnectic Interference) suppression when placed on a wire. This is NOT what you will be using them for. Your usage will be at 0.5 to 10 KHz so I'm guessing that of these mixtures, 77 would work the best for the wire recorder.

Is hookup wire the same as regular electrical wire?

Technically, there is no such thing as "regular wire". Wire comes in various gauges, solid/stranded, tinned/untinned, with various types of insulation intended for different applications.

Hookup wire typically is solid pre-tinned guage 22 to 28 AWG with a thermoplastic easily stripped insulation. The typical hookup wire application requires something that is quickly and easily stripped and can be soldered easily and doesn't have to carry a lot of current and isn't exposed to more than 250 Volts.

[Airfeed143]

Thanks for the help!
I'm in 7nth grade right now, but do not really have any access to testing equipment right now, but I will be getting a multimeter tomorrow or today. I am not working on this project alone, a friend and I are taking this 50/50 so, we hope to accomplish it. Thanks again for the link and telling me what hookup wire was.

[deleted-71588]

This project is deals with low level audio signals. Helpful test equipment in addition to a multi-meter would be an audio tone generator with frequency and amplituded controls and a way to measure signal amplitudes. The parts list calls for one audio amplifier which is used for both recording and playback. A second one would come in handy as a piece of test equipment. I don't see a speaker or headphones in the parts list. You will need something for playback to produce sound.

The core gap is critical and difficult to make. A small vise and a Dremel with a diamond cutting wheel make it easier.

When you make the record/playback head, I recommend that you make two. If you have two amplifiers, you can use a second head as a playback without having to record on wire. By placing the gaps together, you can test out the electronics without having to troubleshoot both the mechanics and electronics at the same time.

[Airfeed143]

Can the magnetic wire be 32 gauge, or does it have to be 34? The instructions say magnetic wire, 34 gauge, Newark.com item #******, or similar. But I cannot find 34 gauge magnetic wire in stores. This is the wire to be wrapped around the ferrite bead. will having it be 32 gauge change anything or will it be alright to use it? I'll look into getting a tone generator. The amplifier is listed inside of the plans, so thats not a problem. Thanks for all the help so far.

[deleted-71588]

Can the magnetic wire be 32 gauge, or does it have to be 34?

This is not an easy question to answer. To understand why, try looking at http://www.ee.surrey.ac.uk/Workshop/adv ... index.html
And if you are really brave: http://www.kettering.edu/~kkaiser/problems/16.pdf to get a feel for how complex the question really is.

Now back to a seventh grade level... The thicker gauge wire will require a bigger inner diameter ferrite to get the same number of turns through it. If you have issues getting a large enough magnetic field at the gap for recording purposes, you won't have the option of using more turns because it won't fit. When it comes to packing density, there is a big difference between 32 and 34 gauge. Try looking for 34, 36, 38, or 40. Smaller is better for this applicaton until it gets too small to remove the enamel without breaking.

The amplifier is listed inside of the plans, so thats not a problem.

Not if you buy two instead of just one that the plans call for!

[Airfeed143]

I will continue to look for 34 gauge magnet wire, and I am confident I will find it in a local store. Thank you very much for all the help you have given me. I am also confident that now I will be able to successfully accomplish this project and hope to receive an A in my project. I will be sure to add you into the bibliography of my project, unless you don't want me to (If you don't want me to just post again saying not to). Thanks again for all the help!
-Nate

[deleted-71588]

If credit is given, it should be given to "Science Buddies Ask an Expert".

[Airfeed143]

ok, That will be done. I am now going to start assembally tomorrow. And again, thank you for all the help Craig, and also thanks to the science buddies website for such a great project.