Science Buddies: "Ask an Expert"

For recording on a wire, I can't get the wire to stay tight around the wheels. any suggestions?

The recorder is built, I have tested the conections, this seems to be the only problem
HELP PLEASE, THE SCIENCE FAIR IS COMING!
thanks,
Babbity Rabbity

Hi babbity rabbity,

I assume you're doing the project at:
https://www.sciencebuddies.org/science- ... ?from=Home

My only suggestion is to carefully read the project description and make sure that you're following all the steps.

My hunch is that the steps that may be causing your problem are:
- preparation of the core including the use of tape (step 2b)
- soldering of the wire (step 4c)

Note, I have no direct experience with this project. Maybe others can help.

:|I have made sure I did not scrape any coating off the magnet wire (if I did, it can cause a short inside the wraping of the core), and the problem I have is with getting the recording wire past the head without it coming off the wheels. I used a digital multimeter to test for continuity, shorts, and opens, so the soldering is fine.

thanks anyway,
Babbity Rabitty

By "wheels" I'm going to assume you mean "spools" or "reels" as in a "source" and "takeup" spools. You need some tensioning mechanism on the source spool to so that it keeps enough force on the takeup spool to keep enough tension on the recording wire so that it keeps in contact with the head gap. You may also need some notched guides to keep the wire positioned so it goes straight across the head and doesn't slip up or down and off the head.

Craig_Bridge wrote:...tensioning mechanism on the source spool to so that it keeps enough force on the takeup spool to keep enough tension on the recording wire so that it keeps in contact with the head gap...

Thanks Craig--
could you give some advice on a tensioner material other than a teflon cylynder (I would have to pay a lot for teflon) ?

Thanks Craig
Babbity Rabbity

One of the simplest ways to obtain a tension force on the source spool is friction. Anything that will apply an adjustable amount of compression force to the "hub" of the spool so that it rubs against a fixed piece as it turns can be used to control the amount of friction and thus the tension on the wire.

We understand how to cut the ferrite core and wrap the magnet wire around the core. Our current problem is that we are unsure how the magnet wire and hookup wire connect to each other and then to the amplifier. Any help would be great because the due date is coming fast.

Our current problem is that we are unsure how the magnet wire and hookup wire connect to each other and then to the amplifier.

Typically you solder the hookup wire to the magnet wire by stripping about 3/8 of an inch of insullation from the hookup wire and gently scraping about 3/8 of an inch of enamel from the magnet wire and then wraping the magnet wire around the hookup wire and soldering the connection. As far as hooking up the connections to the amplifier, that will depend on what connection provisions the amplifier input has. Typical connections may involve a jack and you have to wire to a mating plug or they may involve solderless hookup points like 5 way binding posts or screw terminals or they maybe solder connections. Without seeing the amplifier I can't be more specific.