Electronics > Metrology

LTZ1000 Supply

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e61_phil:
Hi,

I'm working on a LTZ1000 reference and I would like to transport this thing to an calibrated 3458A without powering the reference down. So, I need a battery solution. I think three sealed-lead-acid 6V batteries could work fine. One can also use the batteries for precision measurements without any ground loops for days.

The build in power supply should keep the batteries (current limited) on 20.4V (standby use of the batteries) if connected to line voltage.

My question is: should I supply the LT1013 directly with the approximately 20.4V from the batteries and rely on the PSRR of the LT1013 or should I insert a LM7815 to isolate the changing battery voltage from the LT1013?

Thx
Philipp

Andreas:
Hello,

see my measurements here (and the following post)

https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg842662/#msg842662
I have around -0.3 .. -0.4 ppm/V on my samples without stabilisation.

With stabilisation I have a positive PSRR 0.1 .. 0.2 ppm due to the heating of the SMD voltage regulator on the pcb.
https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg846835/#msg846835

So you should keep power consumption as stable as possible near the reference.
(so the LM7815 far away from the LTZ).

With best regards

Andreas



e61_phil:
Ok thanks :)

I will integrate a voltage regulator out of the LTZ1000 housing.

acbern:
If you transport it, you better transport it to a calibrated voltage reference, this gives you much better accuracy than a 3458A. There are certainly some guys here, depending on where you live exactly in G, who would support you with this, including myself.

e61_phil:
The calibrated HP 3458A is the best I can get here. But your suggestion sounds very good.

I'm from Bremen. Is there anybody around here?

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