Tape imaging

Al Kossow aek at bitsavers.org
Fri Aug 12 14:55:42 CDT 2016

On 8/12/16 10:14 AM, emanuel stiebler wrote:
> 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?

had to dig up my notes from 2013

the drive I have is 18 track (3480 head) with 18 NE5592D differential amps
the A/D is a AD7322 2 channel 12 bit 1msample
I have no idea what the actual sample rate used is
and I can't really tell from the picture in the presentation

>> 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?

I would be happy just to get this one running. I'm not too keen on digging for more head stacks right now.

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