Hi Magnus,
Yeah, I like a challenge, but let's keep things reasonable! :) The
package conversion is easy to accomplish, the FPGA would be a real
stretch for me, but reverse engineering the system code is more than I
want to tackle - although I have thought about it!
Ed
On 5/14/2014 11:17 AM, Magnus Danielson wrote:
Hi Ed,
You could probably use a 32 bit DDS, but there will be a whole bunch
of little trimmings you would have to do in the CPU code which would
require quite a bit of (interesting) work. I would say it would be
beyond the scope of most folks.
Cheers,
Magnus
On 05/14/2014 06:53 PM, Ed Palmer wrote:
Hi Corby,
Thanks very much for the offer, but it looks like it would still be a
big project to use an '1175 to replace an '1173. I think I'll have to
pass.
The package difference (PLCC68 vs. PLCC44) would still require a
daughterboard of some sort. I've learned a little over the past week
about NCOs and, if I'm right, reducing the clock speed from 45 MHz to 30
MHz would partially compensate for the 32 vs. 48 bit difference. The
output frequency would be correct, but the waveform would have more
harmonics. Since the clock is derived from a 90 MHz signal, the
reduction would be easy. Whether that would have an adverse impact on
the operation of the Datum 4065A is way beyond me. It looks like both
chips have a 12 bit output which is nice. The '1175 has more features
than the '1173. I'd have to study the data sheet to see if they can be
configured to make the '1175 act like an '1173.
For now, the plan is to try and source the '1173 in the 48-pin DIP
package and do a (relatively) simple daughterboard to adapt the
packages. Even that will probably end up costing ~$150. If that
doesn't work out, there's the possibility of an FPGA replacement. That
would likely allow replacing the AD9713 D/A converter as well as the
STEL-1173. It turns out that an NCO is a standard application in the
FPGA world.
Ed
On 5/14/2014 9:13 AM, cdel...@juno.com wrote:
Hi,
I found two PLCC STEL 1175 in a rack mounted synthesizer I have.
I'd be willing to sell the chips.
Would they work?
Cheers,
Corby
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