PAUL James wrote:
> All,
>  
> I am wondering if anyone here knows anything about the amount of drivre
> signal that needs to be fed to a Magnetic Stripe Recording Head to allow
> it to record onto a magnetic substance similar in properties to the
> magnetic stripe like on the back of credit cards or ID cards, etc.?
>  
> I want to use a mag card head because of the mounting mechanism on the
> head itself.  I plan to record onto a piece of paper that has metallic
> particles glued to it's surface.  If this works like I want it to, I can
> put together a demonstration that will be interesting for all.
>  
> I've checked the web, and have found the ISO standards that are followed
> by the Mag Card industry, but I don't see mention of the signal strength
> to apply to the recording head anywhere in those documents.  Unless I
> missed it, this info just isn't there.  
>  
> This is for a demonstration and possible utilization later, but in no
> way do I have anything illegal planned for this unit.  It's mostly to
> prove a point to myself,
> and to a couple of skeptic brothers-in-law that think they have it
> figured out that this won't work.  I plan to prove them wrong.
>  
> If anyone has this info, I would appreciate hearing it.     You can
> reply offline to me at jim@jpes.com.

But the whole POINT of the piclist is to share such information.

The write current will be a function of the particular magnetic head.
Typically a few milliamps but you really should contact the manufacturer
to be certain.
5V drive is common for card heads, but you can always start with lower
current (it's inductive so current mode drive works better over a large frequency
range) and work your way up until you're erasing existing data (saturation recording).

Linear audio heads have 80V of 60kHz bias applied, but the audio drive is
only a few volts there as well (much higher head impedance).

There is a very old (1980s?) book called "Magnetic Recording" which has a huge
amount of information on this 'ancient' technology.

Robert
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