Are erase and bias wave forms asymmetric for efficiency?  
MI> Hmm, can't say as I've ever seen a tape deck that used Hall effect device
MI> playback... interesting concept!
What are these?
Dual turntables used them for speed sensing.  A Spacebase (tm) article
says NASA flies one or more in a current satellite.  I think they're
used in data disc drives and maybe Hitachi used them in a cassette deck
(for recording and playback?  ).  I've seen integrated circuit Hall
devices.  Hall units are used in automobiles.  
The most -sensitive- magnetodetector is a SQUID (Superconductive QUantum
Interference Device), or was.  
MI> The maximum reproduceable frequency of any magnetic pickup is direct
MI> proportional to the width of the headgap; any signal whose wavelength for
MI> cycle is less than the width of the gap, will effectually not be reproduc
MI> 
MI>  KP> Certain play heads can read shorter wavelengths than record heads
MI>  KP> can write, for equivalent gap size, because ?    
MI> 
MI> See above.
Some heads are made using lithographical processes, like IC's,
I think. 
A current interest is quantum semiconductors or single electron
circuits.  Could these work as tape heads?!
                                                                  
MI> narrow the gap in the playback head, the higher the frequency that c
MI> reproduced.  However, the wider the gap in the record head (to a certain
MI> practical point, of course), the stronger the signal that can be applied 
MI> the tape.  This is why "professional" decks have separate record and play
MI> heads.
I've seen test reports that show 3-5 khz wider frequency response from
cassettes.  Some mount the separate heads in a single housing so
there's less to adjust.
* Origin: la Point Strangiato... (1:153/7040.106)
Now playing the main title to "The X-Files" TV program HA HA HA HA!!! !   
...
 * ATP/qwk 1.42 * The man in the launderette is looking through your 
underwear.
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 * KMail 3.10m  1996:  The year of the BBS!
--- QScan/PCB v1.19b / 01-0530
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