These ~$20 AD584 based precision voltage references
have been discussed here before, but I wondered about recent experiences with them. To start, I'll share my own.
I ordered
one of these devices off ebay from 1984yht888, a seller mentioned in one of the previous threads. I'd recently purchased another item from 1984yht888, and was impressed that they had a tracking number to me in less than a day, with the item being delivered from Shenzen to Seattle in 6 days. This time, the tracking code was again provided quickly, but delivery took a still acceptable 11 days.
The item arrived packed in a padded envelope. Inside, it was further wrapped in multiple layers of bubble wrap. Inside that was a ziplock bag containing the device, which was wrapped in a small piece of fabric to protect the acrylic case.
The lithium ion battery was in place and charged enough to put the device through its paces. The unit I acquired had a calibration "certificate" on the bottom. The certificate identified the calibration device as a Agilent 34401A, the calibration date as "2015" and temp as 18C. This information, and the nominal voltages, was all computer printed. The measured voltages were written in pen.
I bought this to have a sanity check for my UniT139C DMM, and, not surprisingly given people's reports for both this voltage ref and the 139C, my readings were a good match for the readings on the calibration certificate, given the precision limits of the DMM.
Later, I had a chance to scrounge up a barrel connector that was compatible with the power socket on the unit, and used to it charge the device off USB. Given the low current drawn, and the quick ramp down, it appears that the battery was nearly fully charged when I received it.
None of what I've said so far really merits a post though, but there are a few things I thought worth noting.
In previous threads, some people reported that the battery had been punctured by through-hole leads on the bottom of the PCB. My unit had the battery fixed to the bottom of the case, and plenty of clearance between the PCB bottom and the top of the battery. I don't know if the battery is thinner, the enclosure taller, or the PCB mount higher.
On the other hand, the problem of banana plugs on test leads sticking through the bottom of the open sockets and contacting components on the PCB hasn't been addressed in any meaningful way. Given this, I doubt there has been any revision to the enclosure height or the PCB mounting position.
The main reason for my post though, is that I didn't really pay attention to what version of the AD584 was in the device I ordered until after I received it. As it turns out, the listing was for an AD584KH, and inspection of the marking on the can confirms that is what I received. Previously, these devices have had the somewhat higher-spec AD584LH variant, and most of the ebay listings still claim to be for AD584LH. I also note that the Taobao that I think is the origin of all these devices, currently only lists the KH variant, though they have in the past offered both KH and LH versions.
So, if anyone else has ordered one of these recently, what did the listing claim? What did you actually receive, based on the markings on the can?