Got to be woth £20 uk

[Fraser]

To be clear, the Chines unit is NOT a voltage standard, it is a reference...... meaning it generates a stable voltage that may be accurately measured by a calibrated meter and the voltages recorded for comparison with an unknown meters readings.

The Chinese unit is not calibrated. It generates the set voltages from the reference IC and should continue to produce those voltages  for a reasonable period of time and over a reasonable temperature range.

A voltage standard should produce far more accurate voltages than these units i.e.

2.50000V
5.00000V
7.50000V
10.00000V

[alm]

Two properties are important: stability and calibration. You can look up the stability specs for the two references and compare. The Chinese one has the advantage that it was calibrated on a fairly accurate Agilent 34401A. As Aurora states, the actual value is of little importance, as long as it's known accurately, which it is in the case of the Chinese reference.

The Chinese unit is not calibrated.

Measuring the output and writing the values on a piece of paper is calibration. It's not NIST-traceable and you may or may not decide to trust it, but it is a calibration.

A voltage standard should produce far more accurate voltages than these units

More accurate voltages or nice round numbers? This difference is rarely important, since most meters can be calibrated with any arbitrary voltage within their range. To me this could qualify as a transfer standard, though not the most accurate one. Even calibration of 'real' transfer standards like the Fluke 732B often consists of very accurately measuring its output voltage. There's usually no compelling reason to adjust it to exactly read 10V or 1.018V.

[tmammela]

One reason why these are so cheap must be that they are not burned in. I just ordered a DMMCheck Plus from voltagestandard.com and they have 250 hours of burn-in to stabilize the chip a bit. Here: http://www.voltagestandard.com/Tech_Data.html you can see that during those first 250 hours stability is really poor. So if you get a cheap chinese one, it might be ok for the first few hours but then it will drift out of spec.

[Mr Smiley]

One reason why these are so cheap must be that they are not burned in. I just ordered a DMMCheck Plus from voltagestandard.com and they have 250 hours of burn-in to stabilize the chip a bit. Here: http://www.voltagestandard.com/Tech_Data.html you can see that during those first 250 hours stability is really poor. So if you get a cheap chinese one, it might be ok for the first few hours but then it will drift out of spec.

If anyone who gets one of these checks their meters and records their measured values, And the modules drift over time till, as you say, burnt in, and then measures them again with the same meters, could the new measured values be used to determine the drift and new burnt in values for the module 

[mianchen]

What is the definition of burn in? All these Chinese Refs are made with salvaged/used/old AD584 pulled from other devices, surely they have already been used for many a hour before their new lives in these Voltage Refs

[Mr Smiley]

Hi,

Has anybody had one of these on long term test 

 

[ddrl46]

Ordered one of these about 2 months ago and I still haven't received it, probably due to the recent lithium battery screening from Hongkong post.

[staxquad]

AU $1.00 upgrade to the Volt Ref

adding mini USB recharging capability (rather than plugging in 5v from a wall adapter)

plugged in the USB mini cable from my laptop to charge, then moved the plug to my camera to upload the pictures 





Durable 1PCS 5V Mini USB 1A Lithium Battery Charging Board Charger Module B98B
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=231099090848

[Mr Smiley]

Don't these units already have a lithium charger built in 

I can see the advantage of using a standard off the shelf usb lead 

ps, just got mine, took 5 weeks. I noticed that mine has a cal temp of 20'C ( I'm in the UK where things are calibrated at 20'C ) and others I’ve seen on line, like yours have a cal temp of 23'C.

I wonder if their temp calibrated ( just measured, cal would mean adjusted ) for specific regions 

 

[KJDS]

Don't these units already have a lithium charger built in 

I can see the advantage of using a standard off the shelf usb lead 

ps, just got mine, took 5 weeks. I noticed that mine has a cal temp of 20'C ( I'm in the UK where things are calibrated at 20'C ) and others I’ve seen on line, like yours have a cal temp of 23'C.

I wonder if their temp calibrated ( just measured, cal would mean adjusted ) for specific regions 

 

I'd put money on it being what ever temperature their thermometer is showing at the time

[mianchen]

Or check the weather forecast of Shenzhen before you order if you want a specific cal temp.

sent from Mars

[SeanB]

Mine is in the post thanks to Frankie, and I have a nice little BLB-2 already waiting for it. Tried this battery which has been on a shelf for about 5 years and it still had 3.7V on it. Charged for an hour to 4.0V and it was still very happy and is sitting at 3.79V.

[M0BSW]

I bought one of these and I have to say, mine is a very accurate device indeed and measures , exactly to the certificate with it. to my surprise both my Ideal Alphatek meters measure spot on, uni T 61E is out by 2 counts.

[Macbeth]

Thanks for this thread. I found the cheapest on ebay with cal cert, battery, etc. to be just £11. But they will not ship to the UK, my guess being HMRC customs have been targeting that particular seller for the Lion battery. So cheapest I found was £12.73. With paypal $/£ rate extortion it ends up at £13.15 delivered.

Wish me luck! I did ask for a certificate, we shall see.

[Fraser]

The lithium batteries were being targeted at the source post offices but I suppose the UK postal service may have been identifying them as well. If so I would expect the RM to advise the addressee though. I had a total of two go missing in transit.

An option is to have them shipped without the battery and then fit your own. I have a box full of such mobile phone batteries if needed 

[Monkeh]

AU $1.00 upgrade to the Volt Ref

adding mini USB recharging capability (rather than plugging in 5v from a wall adapter)

What's the IC on that?

[staxquad]

AU $1.00 upgrade to the Volt Ref

adding mini USB recharging capability (rather than plugging in 5v from a wall adapter)

What's the IC on that?

the miniusb charging IC is the TP4056 http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf

the VoltRef onboard charging IC is the UN8HX  http://www.rcgroups.com/forums/showatt.php?attachmentid=5602321

[Mr Smiley]

Mine has gone suicidal, it's now on top of the Christmas tree as the main lighting display in the window. People are knocking asking where i got it from 

Won't turn on from the switch, all leds flashing together randomly, battery charges to 4.1v, when it does take it's medicine and turns on, only stays on a few minutes and then starts its light display 

Anybody sketched out the circuit or had the same problems.

Seller sending a replacement 

[Fraser]

I would always suspect the lithium battery as it may even be a recycled or poor quality item. Try running the unit with a lab power supply providing power instead of the lithium battery (not via the charging circuit but direct to the battery input.

[Mr Smiley]

Hi,

Tried a stable bench supply in place of the lith bat, got absolutely bugger all from it, wouldn't turn on, didn't do it's Xmas lights display, nowt  left it for a few hours 

Thought I’d buggered it completely.

So i put it all together and it was still as dead as a dodo.

Through curiosity, i connected 5v to the power socket and it came back to life 

So i took it apart again, disconnected the battery, connected my supply and it went into Xmas light mode. So i disconnected the supply and reconnected it, it went into bugger all mode again.

Reconnected battery, nowt, connected 5v and it came back to life in Xmas mode.

The bat is dated 2009

I did find this

AD584LH control board power supply is provided by a lithium battery and can charge the external DC power supply for use, charging UN8HX (5-pin SOT23 package H1JC UN8HX 54B4 H1IE) for lithium flow charge management IC, UN8HX is a constant current / constant voltage charging mode linear single lithium-ion battery charger IC, the charging current up 800m A, UN8HX features include current monitor, undervoltage shutdown, automatic recharge, charge termination status indication and input power is present. 8205A Dual N-Channel MOSFET is used as the lithium protection. Boost the MC34063 (DC-DC switching converter IC), 220uF16V and 101 inductive coils, the main battery (3.7V) voltage increase, the supply voltage to AD584LH purposes. Voltage reference is provided by AD584LH, and 8-pin IC next??guess is used to select a different voltage output.

from

http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fbugworkshop.blogspot.co.uk%2F2012%2F03%2Fad584lh-ad584lh.html

It looks like i have to go on the other side of the  Dual N-Channel MOSFET, haven’t got a schematic and don't know what doing that will do 
 


 

[Fraser]

Ahhhh, I don't play with Li-Ion charge and management circuits so missed the possibility that the power supply in the unit expects to see a Li-Ion battery. A bench power supply obviously looks different to the lithium battery. No Li-Ion battery, no worky 

If its worth your time, you could look for the main power rail that supplies the logic and reference and apply power there (with the Li-Ion battery removed and the normal supply path disconnected) If it works OK, your power management circuit or battery is sick.

P.S. 2009 is old for a Lithium Ion battery that is supposedly 'new' so its either NOS or recycled from a mobile phone.

[Mr Smiley]

Hi,

For all you budding reference owners 

Get out your eye glass, or magnifying glass or microscope and have a look at the track on the outer edge/corner of the pcb, on the same side but opposite the 5v charging socket, it can be seen through the top perspex     

Around where the 10.0v led is positioned

Also looks like problem solved 

 

[mtdoc]

Got one of these today from ebay seller kuyaya520 - looks good but no  "calibration certificate"  with it 

[Macbeth]

Just got mine today, quite quick considering. Came with perspex case, feet, battery and cal certificate. Unusually mine came from Malaysia. I normal get stuff from HK/China.

Seller luzhaokao (luchaokao)

Seems to work, but got nothing with beyond 2 decimal places accuracy to test it with!

[London Lad]

Just got mine today, quite quick considering. Came with perspex case, feet, battery and cal certificate. Unusually mine came from Malaysia. I normal get stuff from HK/China.

Seller luzhaokao (luchaokao)

Seems to work, but got nothing with beyond 2 decimal places accuracy to test it with!

Do you have a link to this seller please?