DRO (Parade raining)

> I don't want to rain on your parade but have you considered how a DAT

works. The tape is flexible and >must wrap around the head to some degree.

The comments were made to maybe steer those interested in another direction.
While I do not claim to be an expert on the subject, I believe that if you
do the research, you will find that not all MR head are the flying type you
are referring to.

>A much better idea would be to use a card reader which is designed to read

a flat magnetic strip. It >would be easy to stick a length of tape to some
plastic and read a magnetic series of ones and noughts >from it.

Parade raining aside, This would work very well if you use a MR head and not
the standard magnetic read head. A standard read head will require a minimum
FRPS (flux reversals per second) to give you a useable output. While this
will work ok for rapid traverse movements, it will not yield any useable
output at slow speeds.

>Several tracks could be read at the same time using a number of head offset

from one another to >achieve resolution, I do not know how close the data
can be squeezed up. The only problem I can see >with this sort of encoder
would be laying down the track in the first place.

Laying down the data should not pose much of a problem. You would want to
vary the encoded data on the strip allowing the use of a multi track read
head. You should be able to design some simple digital electronics to in
effect write the data to the mag stripe in the desired pattern using the
write head. Use of a RPG (rotary pulse generator) to track the movement of
the write head on the stripe, you can accurately encode a consistent bit
pattern on the stripe. Standard ANSI data recorded on your credit cards is
either 75 or 210 bits per inch. While this is not useable resolution for a
DRO, it is by no means the limit to the density that can be recorded. Using
the proper media and write head, you should be able to record at densities
of at least 10 kHz or so.

> Another idea could use a laser read head from a CDROM, these are ten a

penny with every week >bringing out a bigger and faster model. Here again is
a problem of obtaining CD's as a strip to make the >encoder.

While this could work as well, I doubt that its a viable means for those
here in the list to make a functional DRO.

Bill Griffin