12 Aug
2016
12 Aug
'16
10:14 a.m.
On 2016-08-12 10:27, Al Kossow wrote:
physical is a .1 grid of square pins coming off of a
flex cable to the head stack.
electrical is you supply a bias current and directly read magnetic flux with an opamp
OK,
I traced all of that out the last time I made a run at
this windmill. John used an FPGA
development board with an 18 channel A/D, which also controlled modified firmware on the
motor driver
and digitizes the tach pulse to get actual tape speed.
18/36 channels? Which sample rate? Resolution?
Unfortunately, he never sent me the FPGA code, so I
have to come up with my own digitizer and figure
out how to drive the transport. Fortunately, it's a 9914V (vertical mount), so it
isn't auto-loading.
I did get a tape to move to loadpoint from the front panel, so the mods might not be too
bad. He did
send me a disassembly of the microcontroller code with the patches he made.
Reading this presentation, I think he switched to 3490 36 track heads at some point.
makes sense, even as you double the amount of data ...
MANY years ago, I bought a dozen 3480s in Chicago and
stripped them for the heads at my parent's
farm in Wisconsin, so I could try grafting one onto another transport if I had to.
I've been unsuccessfully
trying for years to get the schematics for a 9914 or 9914V (they aren't inlcuded in
the service manual).
So, going for the 36 track heads too?