[volt-nuts] Traveling Standards

[Brooke Clarke]

Hi:

Batteries are considered hazardous material and can not be shipped 
without special Hazmat paper work which complicates things.  I think 
there is an exception for some carriers, but not others, when the energy 
is below a couple hundred watt hours (amp hours times volts).  The 
battery pack  mentioned (2 AH * 9.6V = 19.2 WH).

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/


Bob Smither wrote:
> Andreas Jahn wrote:
>
> <snip>
>
>> Practically I can power a LM399 with 8 NiMH cells (9,6V 2000mAH)
>> for about 2 Days before I need to recharge.
>
> Too short to mail it out and return.  I think a line powered unit 
> makes the most sense (especially in light of your following data).
>
>> I tried better thermal insulation but this has no significant influence.
>
> Haven't tried it yet - thanks for the input.
>
> <snip>
>
>> On my LM399 with a 6,5 Digit instrument (10uV resolution)
>> you will not see any thermal hysteresis.
>> (except when comparing 2 of them in a higher resolution range).
>
> This is what I gather from the data sheet.
>
>> To the diagram: Y-axis is the output of my 5V  24 Bit ADC in mV. 
>> X-axis is time in minutes.
>
> Thanks for the data.  Looks encouraging.
>
>> So I would recommend a power-up time of at least 1 hour or so.
>> The instrument which is used to measure the value will need this too.
>
> Noted. Thanks.
>
> Here are my back of the envelope preliminary design / calculations:
>
> Power transformer / rectifier / capacitor => ~35 Volts DC.
> LM7815A => 15 Volts (regulated).
>
> LM199A: Vout =~ 7 V.
> Set Id =~ 1 mA with an Rs = 8.06 K 1% resistor from 15 V to diode.
> Power on-chip heater from 15 V.
> Rout =~ 1 ohm => delta Is of 7 uA causes 1ppm shift.
>
> Require Zin of measuring VM > 10M => 0.7 uA => 0.1 ppm error.
>
> LM7815 TC =~ 1 mV/C => 0.125 uA/C => 0.018 ppm/C.
> LM7815 line regulation =~ 13 mV/V.
>   For 35V +/- 10% => 46 mV => 5.7 uA => 0.813 ppm.
>
> Rs TC =~ 100 ppm/C => dIs/dT =~ 100 ppm/C => 0.1 uA/C => 0.014 ppm/C.
> Rs stability =~ .5% / 1000 hrs => 5.0 uA => 0.714 ppm.
>
> Comments - feedback?
>
> The two largest errors (other than 20 ppm stability of the lm199ah) 
> are both under 1 ppm.  They could be reduce further but is it worth it 
> given the stability of the lm199a?
>
> Best regards,
>
> Bob Smither
>
>
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