[time-nuts] Some pics of the Datron 491x DC reference cell

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Feb 1 23:21:30 UTC 2009

Dr. Frank Stellmach wrote:
>  > NB use the latest datasheet which has a corrected schematic showing the
>  > location and polarity of the parasitic diodes.
>> Bruce
> Thank you, I already got that...
> When I used the first datasheet, I reversed the heater as there was no hint, just to discover those hidden parasitic diodes.
> I obviously did not damage the device (hope so), but sent that info to LT, and then they did the correction.
> Frank

Yes but they didn't correct the negative reference circuit.
I notified them about that - maybe that will be corrected in the next

I've located my Vishay brochure on resistor networks from the 70's.
The TO-5 can resistor networks used 50 mil x 50 mil (50mW) and or 150
mil x 50 mil (100mW) resistor chips wire bonded to the header pins.
Either 8 pin(2 different pin circle diameter options) or 10 pin variants
were available.
Other than the resistor chip specifications (TCR, pwer dissipation, etc)
there's not much else.


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