Nice... 80 bucks, 70 Euros maybe, made in Germany so cheap shipping for me I guess.
A potential next step ./ upgrade from my cheap Chinese AD584...
The github is here if you feel like building your own: https://github.com/circuitvalley/LM399_Voltage_reference
For most of us, I still believe the DMMCheck/DMMCheck is the best bang/buck, as it comes with a variety of standards to check pretty much all the modes of a common DMM.
IIRC, the consensus was that it is adequate reference for up to 4.5-5.5 digits, or as a transfer standard for higher...?
https://dmmcheckplus.com/technical-information#
mnem
![DMM :-DMM](https://www.eevblog.com/forum/Smileys/default/smiliey_dmm.gif)
Oh yeah the DMMcheck of course, how could I forget about this one !
Hmm.. let me see the pros and cons of each product.
Circuit Valley :
- Half the price
- Open H/W.
- 10V output which is versatile, allows me to test all the digits all my DMM : 3,200 counts, 4,000 counts, and 50,000 counts.
- Super accurate.
DMMCheck :
- 5V output won't let me test properly my 3,200 and 4,000 meters, I would lose a precious digit. Even my 50,000 count meters well... the ref could still make them overflow and again lose the MSD.
- Less accurate than the other one.
- Twice the price or maybe more, their site doesn't say how much it would cost, shipped, when buying from their German stock.
- Features I don't need/want : frequency and duty cycle and AC.
- Good : does current, and offers a few precision resistors.
So if I could be arsed, the best bang for buck for me only for meeee.. would be to mix both products.
That is, make my own PCB, using the CircuitValley one and add precision resistors to the board, and add current as well. I guess I could simply connect the on-board precision resistors to the Vref and call it a day. The shunt value of the DMM ammeter would be much less than the ref Resistor on the board so it would still be plenty accurate enough for a very decent sanity check.
Oh, does that mean I have just added yet another project to my pile of projects ?!
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)