[time-nuts] Fine print on HP 5334B

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Feb 22 23:46:57 EST 2007

Hal Murray wrote:
>> Every time I dig through the 5370 schematics, I think to myself
>> "wouldn't it be nifty to build a replacement plug-in card with a
>> modern fast CPU to run the instrument", but I try and stop myself
>> there. 
> Suppose you start with an FPGA on a PCI card.
> What sort of front end would you want?  What can you build with home/hacker 
> technology?
> My straw man is something to turn a digital signal out of a comparator into a 
> ramp that gets feed into an A/D clocked on the system's internal clock.  The 
> ramp needs to be a little over a cycle wide.
> Anybody got a circuit to make a linear ramp?
> Maybe the front half of the standard R/C exponential is good enough.  Fixup 
> the non linearities in software.
> Somebody has mentioned a chip that does all this magic.  I forget the number 
> but it's in the archives.  I think it's European and maybe a touch pricey but 
> maybe not if it avoids the A/D and friends.

for time to digital converter chips.

You could fit the entire replacement design on a relatively small single 
A pair of TDC chips plus an FPGA and a processor would be all that's 
required other than the input amplifiers and the IEEE 488 interface.
However it would be necessary to use at least a 4 layer board with 
surface mount devices.
Cost would way less than a new 5370 if they were still in production.


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