Science Buddies: "Ask an Expert"

The diagrams shown for the project leave out the mounting of the ferrite in the read/write head. I am require to cut a gap in the ferrite, but how deep? What is the length of magnetic wire that will give me 220 wraps?
I need help today...

I would consider moving your question to the "Physical Science" forum. You would be able to find better experts over there for this topic.

The ferrite core is shaped like a ring. So your cut needs to go all the way through the ring. Find a place on the ring that you want to make your cut, and cut it all the way through. Here's a diagram of the ferrite core from a top-view to help you visualize what you need to do:



As far mounting the ferrite core onto the rest of the contraption, I think you can use whatever mechanism you can come up with. In terms of the length of wire, I'm just estimating here, but it looks like you'll need about one inch per turn, so a total of about 220 inches.

Hope that helps.

--Rajeev

I can cut the ring core, but I only have 30 guage wire, so I may not get 220 turns of wire. Where or how do you secure the core. What type of bracket or clamp did you use and where did you find a clamp?

Hi,

I have moved your thread to the physical sciences forum, where I think you will get more help.

Good luck!

Where did you come up with a desire for 220 turns on a read/write head for wire recording?

Even if you used AWG 40 which is about the smallest easily obtained, you would need a huge core to get 220 turns. The amount of energy needed to reverse the magetic field in the core is a function of the size of the core and the frequency at which you want to reverse the field.

Typical commercially available recording/playback heads for tape recorders will have fewer than 20 turns.

There is another reason why you want to use fewer turns and that is inductance. The more turns on a core the more inductance the pickup coil will have which will significantly affect the frequencies that can be recorded and picked up.

How many turns of magnetic wire do you need on such a small core? I cannot find any steel wire only steel Galvanized wire. I have my recorder built but no recording has occurred.

Craig --

The reason this student was trying to put 220 turns of the wire onto the core was because that's what this Science Buddies project says to do:

https://www.sciencebuddies.org/science- ... p015.shtml

I agree that seems like a lot more than you'd need, but I didn't know with any certainty how many turns are actually required.

--Rajeev

Do you have access to an oscilloscope? If not, do you have a second identical core that you can fabricate a second "head" out of and another amplifier that you can use to trouble shoot with? You need to measure the magnetic field at the gap when you are recording and compare it to the field required to magnetize the wire. This is a very difficult project to get working if you don't have access to some test equipment and trouble shooting skills to make use of the equipment.