Re: [CAD_CAM_EDM_DRO] DRO (Parade raining)

There might be something useful here.
The thought of controlling a plastic tape, glued down or otherwise, does not
sound encouraging but why use plastic tape?

Remember the early wire recorders used a metallic wire! If the pattern is
written on a wire or metallic strip it will be mechanically stable.
Bertho Boman
======================================

Tyler Griffin wrote:

> > 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