What are these relays? - Page 1
Forum section: electronics / general

author: primegaps
author_rank: Contributor
timestamp: March 01, 2017, 09:05:44 am
content: Hi! I'm a real electronics beginner, but I've found that I'm obsessed with older analog gear, and I'm just starting to get into the more modern stuff. I have quite a bit of electronics experience from schooling, but I have not messed around much on my own at all.I have these mercury wetted contact relays, made by Potter and Brumfield and I wasn't quite sure what they were or what i could do with them.They look gorgeous and are so shiny it hurts. I can't find any information on the particular model i have, although I see a few other similar looking models for sale on ebay and the such. If you know anything about these, I would love to know! So far, they just sit with my other old stuff in my collection.These two each have a different graphic silkscreened onto them, but they are the same model.Thanks for reading!

author: fubar.gr
author_rank: Unknown
timestamp: March 01, 2017, 12:11:46 pm
content: These are socketed relays for switching big electrical loads like motors. The sockets are usually DIN rail compatible for installation in standard circuit breaker boxes.They come in pretty much standard pinouts for easy replacement. Here is a modern one, although the pinout doesn't match

author: Gyro
author_rank: Super Contributor
timestamp: March 01, 2017, 12:24:25 pm
content: They are rare treasures these days due to the phasing out of Mercury in products (don't worry, the mercury is safely hermetically encapsulated). The overriding advantages of Mercury wetted relays are:1. Wetted contacts () - They are capable of switching down to zero current and zero voltage (very useful for signal level switching - instrumentation or maybe audio).2. Zero contact bounce - They are the only mechanical relays capable of this feat.3. Low and predictable contact resistance.4. VERY long contact life - because the Mercury contact film is reniewed each time they switch. Life of 10^8 operations is not uncommon if used within contact ratings.5. Normally fast operation.6 High isolation.Many of these features can be achieved by modern solid state relays etc, but not all at the same time. Treasure them.P.S. NOTE that they are normally position sensitive (because they contain liquid Mercury). There is usually an arrow on the can indicating orientation - normally vertical, pins down. Oh and they only work down to -38'C, where the Mercury freezes.

author: capt bullshot
author_rank: Super Contributor
timestamp: March 01, 2017, 02:18:22 pm
content: Where did you get them? Want some too.

author: retrolefty
author_rank: Super Contributor
timestamp: March 01, 2017, 02:30:13 pm
content: Those look a lot like the relays we used in Teletype 0-20 or 0-60ma current loops in the Air Force.

author: daqq
author_rank: Super Contributor
timestamp: March 01, 2017, 02:46:43 pm
content: Quote from: capt bullshot on March 01, 2017, 02:18:22 pmIf you want a few, contact me, I've got two or three (of a different type) that I can't use for shipping costs.

author: bji900
author_rank: Contributor
timestamp: March 01, 2017, 02:56:15 pm
content: Socketed relays like this are still used today. They are fairly common in industrial equipment. See Link for similar socket that is a standard used on modern equipment today.http://www.alliedelec.com/custom-connector-ob08-pcb/70102757/

author: daqq
author_rank: Super Contributor
timestamp: March 01, 2017, 03:05:11 pm
content: QuoteReally? I assumed that RoHS meant their death. Is there an exception for this?

author: edpalmer42
author_rank: Super Contributor
timestamp: March 01, 2017, 05:04:04 pm
content: Quote from: fubar.gr on March 01, 2017, 12:11:46 pmNo, not these ones. I'm familiar with both types. These relays are for low power signals as stated by the other posters. The relays that you're thinking of are indeed for switching large loads. I've got a couple that are rated for 30A@115V or 20A@220V.Ed

author: Benta
author_rank: Super Contributor
timestamp: March 01, 2017, 07:36:49 pm
content: Lovely!Do they plug into a vac tube octal socket? It's hard to estimate the physical size of them.

author: james_s
author_rank: Super Contributor
timestamp: March 01, 2017, 08:10:40 pm
content: Assuming they're the size I think they are then yes, although usually you find them in DIN rail mountable sockets but I have seen tube-style octal sockets chassis mounted in equipment before.

author: bktemp
author_rank: Super Contributor
timestamp: March 01, 2017, 08:15:23 pm
content: Yes, those relays use the same socket as some vacuum tubes.The 11 pin variant is JEDEC B11-88.

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 01, 2017, 08:32:59 pm
content: You could open them up and drink the mercury and make a youtube video of you doing it.

author: edavid
author_rank: Super Contributor
timestamp: March 01, 2017, 08:33:13 pm
content: Quote from: fubar.gr on March 01, 2017, 12:11:46 pmI want to emphasize that this is wrong. These relays would be destroyed by switching power loads. Fubar, please delete your misleading post.

author: Benta
author_rank: Super Contributor
timestamp: March 01, 2017, 08:41:12 pm
content: QuoteI agree 100%. I'd think these are for audio or video switching in high-end equipment. Or test/measurement.

author: Seekonk
author_rank: Super Contributor
timestamp: March 01, 2017, 08:45:39 pm
content: And no one has mentioned CHOPPER. Feed 60cy into this coil and it will easily switch at that rate and much higher.

author: edpalmer42
author_rank: Super Contributor
timestamp: March 01, 2017, 09:29:32 pm
content: Quote from: Seekonk on March 01, 2017, 08:45:39 pmGive the man a prize!! It is a chopper relay!I found it listed in a 1968 catalog from Electrosonic, a Canadian distributor. See, dead tree books do still have a use!JM SeriesJML sensitive, form C, non-bridgingCHOPPERCapsule: JMLCoil: 8130Terminal Figure #: 81 (just shows the same picture as the one on the relay).Coil CharacteristicsResistance: 600 ohm +- 10%Voltage RMS 60 Hz: 6.3VThe price was $15.45. I shudder to think what that would convert to in today's dollars.Other relays in the JML series were shown as 'SINGLE SIDE STABLE' or 'BI-STABLE' instead of 'CHOPPER'. Does that mean that this relay isn't stable at all? Is it open on both sides and only makes contact when it's powered by AC? Don't know.Descriptive info on the JM series is as follows:Rare long life, high speed, and unvarying dependability - all are the result of the basic component of these relays: a hermetically sealed glass capsule. It contains the contact arrangement and a small reservoir of mercury sealed in a high pressure hydrogen atmosphere. A film of mercury is renewed for every operation - that's why you can think in terms of billions of operations without contact bounce, pits or welds.TWO TYPES OF CAPSULESThe capsule used in JMF modules and JML relays has a SPDT, break-before-make (Form C), non-bridging contact arrangement. Each capsule used in JMP and JM1 to JM4 relays has a SPDT, make-before-break (Form D), bridging contact arrangement. JMF, JML and JMP series achieve a high rate of sensitivity by factory-adjusted magnet biasing.CONTACT RATINGSJML: 500V max., and 2 amps max., 100VA max.**With contact protection unless in a low level circuit. Details of a simple protection circuit consisting of resistor and capacitor in series are packed with each relay.Ed

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 02, 2017, 01:26:26 am
content: I believe they also only work in the upright position.

author: edpalmer42
author_rank: Super Contributor
timestamp: March 02, 2017, 02:16:20 am
content: Quote from: Alex Eisenhut on March 02, 2017, 01:26:26 amMy 1968 catalog didn't mention that, but I found another catalog that says:"Mounting position: Upright mounting required, but deviation from upright to 30 degrees causes only minor deviation in operating characteristics."Ed

author: amyk
author_rank: Super Contributor
timestamp: March 02, 2017, 03:17:09 am
content: Those catalogs would be worth scanning and uploading to archive.org, if someone else hasn't already done soApparently these relays are not cheap:http://www.electronicsurplus.com/potter-brumfield-jm2-106-21-relay-mercury-contacts-dpdthttp://www.industrialelectricsupply.net/products/m-jml-1110-81-p-b-mercury-wetted-contact-relayhttps://www.amazon.com/Potter-Brumfield-JML-1190-81-Mercury-JML119081/dp/B01ICIH2FC

author: edpalmer42
author_rank: Super Contributor
timestamp: March 02, 2017, 03:46:18 am
content: Quote from: amyk on March 02, 2017, 03:17:09 amNot....Gonna...Happen.Each one is just under 1000 pages long.I've got 7 catalogs that would be candidates.Ed

author: primegaps
author_rank: Contributor
timestamp: March 03, 2017, 06:36:37 am
content: Awesome, Thanks all for that information. I had no idea they were worth quite that much.So because of the mercury in the relay, it operates only in the upright position, or slightly away from upright. But as for storage, will it be more ideal to keep them upright for the long term?I really would like to display them somehow, but the pins on the bottom form a surface that cannot balance the relay. I have just been keeping them in their original boxes, but they are upside down. Might this be detrimental in the long term?I have the pamphlet fold out that came with the relays, perhaps i can scan that sometime and upload it.

author: Gyro
author_rank: Super Contributor
timestamp: March 03, 2017, 11:46:50 am
content: No, you're fine. The vertical orientation is for operation only - to ensure that the contact faces have just the right amount of Mercury on them (by capiliary action). All the surfaces that are meany to be wetted already are, so you can store them in any position indefinitely without any effect at all. You can even shake them gently next to your ear to hear the Mercury sloshing.P.S. An upload of the pamphlet would certainly be of interest.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 03, 2017, 02:09:26 pm
content: Very nice!Tim

author: primegaps
author_rank: Contributor
timestamp: March 04, 2017, 09:23:10 am
content: Hello all! I can't quire hear the mercury sloshing around in the relays, too bad! Still the coolest shiny things ever. I really would like to make a circuit to utilize these.I have scanned the sheet that comes in the box with the relays for all to enjoy. Apologies, it is quite faded.