Both DMMs are much more noisy and less stable (about 10 times) than the LTZ1000 circuit. The 34401As internal LM399 may produce these 1..2ppm steps. The bigger glitches may be produced by the LTZ1000 circuit, caused by RF disturbances, from switch mode power supplies in your lab. Watch out for LED lighting.. xdevs circuit lacks additional capacitors, which suppress most of these disturbances. I added 2 capacitors to the LT circuit, and things improved a lot, already. So please consult eevblog, the Super LTZ1000 thread for details on Andreas' circuit.

That was a REALLY nice project. Thanks for the upload.

Looks to me that the glitches are related to your presence in the room, this has happened to me measuring very low noise resistors, I would suggest shielding all cabling. Thanks a lot for the video...great info!

Watch the video and am thrilled. In the scene with the housing and the insulation, I realize that a metal housing only makes electrical sense and serves a purpose if it is also grounded to earth. And zipp, zapp zerapp in the next moment he puts a ground cable to the housing. I had to grin. Good work. Thank you.

I have noticed that radiated noise effects very small value uV values, I had to turn off as much switchmode equipment as I could in my lab when using my Fluke 343A DC calibrator ( looks the same as yours except it has one more knob for the uV range)

Very good work

LTZ1000 PCBs always look cool.

Great job, thanks!

Good video, thanks for this. I am on the Volt-nut and Time-Nut path myself now :-)

Great video! What software are you using to display and navigate the graphs?

Too bad you didn't monitor more things: Lab power supply, room lighting, time-of-day, power line changes, etc. I'm not sure I would connect the two DMMs together for this; one at a time might be better. Please let us know what you did to get access to a better meter, etc. GREAT video!

Great video and very informative about the components. I too would like to build one of these circuits. Like you said, with any testing, you need a device that is more accurate than the device you are testing to rule out errors in the test equipment. Perhaps a better reference meter would show a much flatter line - but these type of meter are very expensive. I would be interested to know where you purchased your Vishay Foil Resistors from, because Digikey does not stock these and require a minimum order quantity of 500. Perhaps if you make up 2 of these boards and use each to cancel each other out, then measure the small difference in voltage. This is provided each is very close in output voltage. So you could have a series of boards and read the voltage difference off each pair combination. With a series of boards, it might be found that one specific board has a lower drift than the others and this would become the main reference. Keep up the good work!

Pretty cool, what software did you use for those charts ?

Interesting video. What is the purpose of those circular traces on the PCB around the LTZ1000?

I wonder if that voltage reference device is monolithic on the inside. Maybe the "heater" is a resistor on the die itself? Amazing stuff! Than you so much for sharing! Great data analysis!

Hi, what software are you using for the graphs?

Good job, now build few more boards so you can use 34401A as null-meter between two LTZs, then you can easily see if there are unstability/jumps between LTZs. You mounted LTZ with quite some spacing from PCB. I had random 0.5-0.6ppm jumps when I did similar on one of my boards, and moving LTZ chip flush to the board + adding additional cap on bottom side fixed those jumps. I've also tried extra caps like Dr.Frank/Andreas use, but saw no difference in measurements, in _my specific_ environment. Also I noticed you used same cap on position C4? Reference design has 22nF cap there, not 100nF.

awesome! want to get rid of one of those extra pcbs? i really want to make one of these but dont want to order 3 boards:)

Hello, where did you find the little grip which help you to divert the heat transfer?

I would like to see the histograms..

Is that ceramic-filled laminate?

Very nice video. Its my first time here. I think the UPS could cause a glitch or some changes in the measurments. I am using an APC UPS for my network equipment and this kind of UPS is using an "autotransformer" to step up for example an input of 200V to my setting of 230V. If some time passed by and the input is close to the setpoint (in my case its flucuating between 227V and 229V) the UPS enteres an "ECO" mode and a relay bypasses the autotransformer (which is the backup step up transformer, too). I am not 100% sure because the ECO-mode despripction in the APC manual isn't quite technical. Even if the reference is extremly stable, both instruments could be affectet by the switch over and of course to every change in their input?!

Could cosmic rays cause such glitches i wonder?

So, if the actual voltage is not important at all, why is this good as a voltage reference? I understand that it drifts very little with temperature, but how can it serve for calibration if the voltage is arbitrarily around 7.1 to 7.2V?

How's the reference doing please ?...cheers.

Great video...7.10148...is it still the same ?

excuseme, why accuracy is not mentioned?

indeed use some polarity protection on boards like this with relatively costly components, a simple diode can save your day.

круто

ты русский?

Уж лучше на Русском

first of all do us all a favour.. do not use aluminium case for better TC if you need a cooler or heatsink then don't use such a material that quickly coresponds to temp changes (aluminium) otherwise to acheive a better stability.. use plastic case and foam.. . not plastic foam styrofoam