At 06:33 AM 5/18/2005, Olin Lathrop wrote:
>Philip Pemberton wrote:
>>The big problem is interfacing the magnetic head to something. I don't
>>have the foggiest clue what I need to do to record on the tape. I know
>>there's supposed to be an AC bias signal fed to the record head and the
>>erase head, but I can't find any concrete info on how to determine the
>>frequency and amplitude of that signal. The same applies to playback
>>circuitry - no info on output levels or required amplification.
>
>Is this for digital or analog?  The two are handled very differently on
>magnetic tape.

I can recommend Finn Jorgensen's handbook of magnetic recording.

In short, you have to figure the gap width of the head vs tape speed 
as the minimum wavelength you can store.
Also, for digital data, feed the head with a voltage-current 
amplifier, and read it with a current-voltage amplifier.
Makes life a whole lot simpler.  Much of the mess of hobby data 
recorders was caused by running digital data through circuits 
designed for analog.

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