Looking for any info on a JRL ZVR-106B Voltage Reference - Page 1
Forum section: electronics / general

author: swperk
author_rank: Regular Contributor
timestamp: April 12, 2022, 03:29:16 pm
content: I just found a Julie Research Laboratories ZVR-106B voltage reference. It's a small (5" x 4" x 4") black metal box with five 5-way binding posts on the top labeled GND, -5V, 0V, +1V, and +1.018V. It has a permanently attached AC power cord but also has a rechargeable battery inside whose voltage can be checked via a terminal strip on the side of the unit.I'm not sure how long this particular unit has been unpowered, but I plugged it in and watched the output voltages slowly rise over the course of about an hour to within 0.5% of the labeled voltages. The internal battery voltage rose to about 11.5 volts after being charged overnight, but settled back to 8.75 volts after being off the charger for a few hours.That's as far as I've gotten with it. Does anyone know the background of this reference, or even better, have an operating and/or service manual for it? Google turned up nothing other than the website of a company in Germany that will calibrate and repair them, but it had no technical info.Thanks!

author: tggzzz
author_rank: Super Contributor
timestamp: April 12, 2022, 06:27:47 pm
content: I have no knowledge of that particular unit, so this is worth what you've paid for it.Internal and external pictures would be helpful.I wouldguessthat ZVR implies zener voltage reference, rather than a weston standard cell.What is the nominal voltage and chemistry of the internal battery? There is a good chance that it is, to use the technical term, knackered. If you put a scope across it when charging, is there noticeable ripple?If there are internal electrolytic capacitors, then they may have developed a high ESR - but some types may still be OK.Have you tried disconnecting the battery and (without it connected it to the mains) "simulated" a battery with a bench PSU?

author: alm
author_rank: Super Contributor
timestamp: April 12, 2022, 07:03:37 pm
content: The voltages sounds too random for a general purpose voltage reference, so my guess is that it was designed to be part of a bigger system. The 1.018V could either mean it contains a Weston cell, or it was designed to be compatible with one. If it's solid state, then my guess would be a selected 1N82x-series zener diode. A quick teardown should tell you.

author: TimFox
author_rank: Super Contributor
timestamp: April 12, 2022, 07:03:52 pm
content: I don't know that specific unit either, but I remember (ca. 1978) using a Julie Research packaged reference Zener diode that was supplied with a selected wirewound resistor to establish the current through it. The device was potted in a black cube with a set of pins on one edge that mated with a standard vacuum-tube socket (either 7- or 9-pin miniature, I don't remember now).

author: 1audio
author_rank: Frequent Contributor
timestamp: April 12, 2022, 07:09:38 pm
content: Here is some info from the Optimation/JRL catalog. They are pretty remarkable for the early 1970's. I'll be scanning the whole catalog soon.I have a JRL Voltavider that had its reference stolen but an LM399 reference seems to be working well enough.

author: 1audio
author_rank: Frequent Contributor
timestamp: April 12, 2022, 07:11:51 pm
content: Here is a datasheet on the internal references. They are based on Zeners but very carefully selected and aged.

author: 1audio
author_rank: Frequent Contributor
timestamp: April 12, 2022, 11:17:53 pm
content: I just uploaded the Optimation/JRL catalog to BAMA.

author: swperk
author_rank: Regular Contributor
timestamp: April 14, 2022, 01:20:56 am
content: For the mildly curious, here are photos of the outside and inside of my ZVR-106B. The three rechargeable batteries are pretty much kaput. They are spec'd at 8.4V and 600mAH. The best one of the three is sitting at 7.2 volts, and the other two are in the 1 to 2 volt range. It's time to find or build a suitable replacement battery pack.Thanks to all for the great info!

author: swperk
author_rank: Regular Contributor
timestamp: April 14, 2022, 01:26:58 am
content: Here is another batch of photos (apparently they're too large to post all at once).

author: swperk
author_rank: Regular Contributor
timestamp: April 14, 2022, 01:27:42 am
content: And the final group of photos.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 14, 2022, 02:13:37 am
content: NiCad stuff is the worst because they always floated them no control and the life is short. Every replacement battery pack I've made has failed again within a few years. Not sure of the best alternative but I usually make up a dummy "battery" with a very large electrolytic, shunted with some big zeners to clamp it at the charged battery voltage and absorb the charging current. No, it won't hold power during power outages, but you'll probably find it doesn't matter much.I've always been a JRL fan.

author: tggzzz
author_rank: Super Contributor
timestamp: April 14, 2022, 08:08:58 am
content: Quote from: Conrad Hoffman on April 14, 2022, 02:13:37 amMy Trancell II has gelcell lead acid batteries.QuoteI only have one piece of their equipment, a 7-decade KVD. Very nice it is too.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 14, 2022, 04:58:19 pm
content: I've a higher opinion of gel cells but every one of those I've ever had died eventually too. They can't be allowed to run down or they sulfate and are pretty much done. I used to use a bank of them with my JRL standard cell oven, before I got rid of it.

author: alm
author_rank: Super Contributor
timestamp: April 15, 2022, 12:39:37 pm
content: Quote from: 1audio on April 12, 2022, 07:11:51 pmThanks for posting that! The striking specs to me are the very low tempco and short term stability. It would not surprise me if they were compensating tempcos and reducing noise by paralleling multiple (selected and aged) zeners, like Datron did in their high-end multimeters: the 1081 used four 1N829a diodes, and I've seen calibrators before they switched to the LTZ1000 use 6-8 diodes, depending on the grade of the calibrator. Aging and selecting that many references must have been a very expensive process. The output voltages, which are multiples of 6.3V, suggest at least 1-3 diodes in series, with possibly diodes in parallel at each step.

author: TimFox
author_rank: Super Contributor
timestamp: April 15, 2022, 01:42:07 pm
content: Quote from: alm on April 15, 2022, 12:39:37 pmBesides aging, probably the most important process applied to these references is to carefully measure the Zener current where the forward and reverse-biased diode tempcos of each individual device cancel at the operating temperature.

author: 1audio
author_rank: Frequent Contributor
timestamp: April 15, 2022, 09:39:15 pm
content: Any chemical cell will fail over time. The Lithium primary cells seem to be the longest lived with 10+ years standard. LI rechargeable should be not far behind. Li is so unstable you need really good processing to make the cells. I have seen well cared for nicad and nimh batteries last a long time but early charging circuits look more like something for lead acid than well designed for nickel batteries.When these vintage instruments were made thinking someone would be using them 20-50 years later was inconceivable.I have a JRL Voltavider, a 106/7 KVD and a 6 digit programmable resistor. Also an Optimation AC120 calibrator.

author: tggzzz
author_rank: Super Contributor
timestamp: April 15, 2022, 11:04:11 pm
content: Quote from: 1audio on April 15, 2022, 09:39:15 pmWell, my 72yo chemical cell is still within specification. I wouldn't connect it tomyJRL 106/7, thoughPictures here:https://www.eevblog.com/forum/testgear/muirhead-kvd-and-internal-corrosion-ignore-it-or-fix-it/msg2893912/#msg2893912And I've seen Li cells for calibration constant RAM battery backup working after 30 years.