Banana Adapters BNC, shorting bars, thermocouple, mutimeter leads distance  - Page 1
Forum section: electronics / testgear

author: amar87
author_rank: Regular Contributor
timestamp: January 04, 2024, 04:30:30 pm
content: Hello,I was wondering if there is a standardised distance between multimeter leads that can take all sorts of adapters. Or better put would all multimeter take such adapters(for example banana to BNC)Here are a few examples:https://www.digikey.de/en/products/detail/pomona-electronics/5145/737158?utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=PMax%20Shopping_Product_New%20Customer%20Acquisition&utm_term=&productid=737158&utm_content=&utm_id=go_cmp-19928079281_adg-_ad-__dev-c_ext-_prd-737158_sig-Cj0KCQiAy9msBhD0ARIsANbk0A_W07rSnaYbNoK9blfZgYYjbpzRSHFM-tmPcb8L7R7Q1hUf-Q2972caAlbXEALw_wcB&gad_source=1&gclid=Cj0KCQiAy9msBhD0ARIsANbk0A_W07rSnaYbNoK9blfZgYYjbpzRSHFM-tmPcb8L7R7Q1hUf-Q2972caAlbXEALw_wcBhttps://www.reichelt.de/de/en/bnc-adapter-bnc-socket-2x-pin-plug-k-123-p9020.html?PROVID=2788&gclid=Cj0KCQiAy9msBhD0ARIsANbk0A-YPXkeWOe1jDqUGirZAvm5O8pZEK3a7B4NRWa8xGPY2DChscYjXmUaAlWgEALw_wcB&&r=1

author: RoGeorge
author_rank: Super Contributor
timestamp: January 04, 2024, 04:34:34 pm
content: Yes, standard distance and standard banana diameter, they should fit in any decent DMM, power supply, etc.

author: alm
author_rank: Super Contributor
timestamp: January 04, 2024, 04:35:41 pm
content: Yes, the standard spacing is 19mm (3/4 inch) which is pretty universal for adapters and most multimeters.

author: amar87
author_rank: Regular Contributor
timestamp: January 04, 2024, 04:53:28 pm
content: Thanks guys !!

author: JohanH
author_rank: Frequent Contributor
timestamp: January 04, 2024, 05:04:48 pm
content: I'm seeing a lot of mentions of "standard", but I haven't yet seen a reference to an actual standard. IMHO, it's only a de facto standard, not defined anywhere. TLDR, according to Wikipedia the dual "banana" spacing of 3/4" or 19 mm (or 19.05 mm?) originates from General Radio test equipment in the 1920s, specifically their type 274-M dual-plug.Edit. Link:https://en.wikipedia.org/w/index.php?title=Banana_connector&section=3#Derived_plugs

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2024, 05:09:52 pm
content: Yep, it’s 3/4”. That’s 19.05mm, but of course one can just round that to 19mm since a banana plug has more than 0.05mm of play anyway.

author: amar87
author_rank: Regular Contributor
timestamp: January 04, 2024, 05:15:07 pm
content: Maybe it's just a convention

author: alm
author_rank: Super Contributor
timestamp: January 04, 2024, 05:38:17 pm
content: Quote from: JohanH on January 04, 2024, 05:04:48 pmYou have to distinguish between standard as a noun, like in "IPC standards" or "the IEC61010 standard", and standard as an adjective, like in "a standard linear regulator circuit". The means it's a common, basic, frequently used circuit, not that there's any ISO standard on linear regulators. I don't think there's a standard for 4mm banana plugs either, yet people will write "standard banana plugs" as opposed to more special (e.g. sheathed) banana plugs.

author: JohanH
author_rank: Frequent Contributor
timestamp: January 04, 2024, 06:14:46 pm
content: Quote from: alm on January 04, 2024, 05:38:17 pmThanks for clarifying. I do know the difference, but sometimes my English might be lacking some nuance. I think it's of interest in this forum, though, to mention if something adheres to some electrical standard or not. I've myself wondered about banana plug dimensions and spacing in the past and it's not far fetched to think that they could be mentioned in some paper or the other, but apparently not.

author: alm
author_rank: Super Contributor
timestamp: January 04, 2024, 06:21:20 pm
content: I don't think it's common for connector spacing to be specified in any formal standard, though I'm sure someone can find an example.For BNC jacks there is also common spacing used in LCR meters which usually have 4x BNC as inputs, but this is also a de-facto standard that is not even common across all major manufacturers: I think HP/Agilent/Keysight and Wayne-Kerr use different spacings.

author: amar87
author_rank: Regular Contributor
timestamp: January 04, 2024, 07:19:36 pm
content: that wikipedia article is nice i googled 'distance between multimeter leads' and could not find anything. Maybe some manufacturer chose the 19mm and then everyone decided to stick with it. So apparently this is a 'thing' right?

author: RoGeorge
author_rank: Super Contributor
timestamp: January 04, 2024, 07:48:05 pm
content: I guess that distance might come from a time that precede DMMs, and it might come from the standard for mains power socket outlets.Here in EU/Ro we have household mains power plugs (220-240V/50Hz, 2 round pins + a sideways grounding optional, as 2 sideways metal bands embedded in the plug, not a 3rd pin)First type has a little thicker pins, but the second type seem to have the right thickness, and both with the same spacing as that banana-to-BNC adapter.Though, this is just a guess of mine, I didn't try if the banana to BNC adapter fits into the mains outlet.

author: alm
author_rank: Super Contributor
timestamp: January 04, 2024, 08:04:31 pm
content: Quote from: RoGeorge on January 04, 2024, 07:48:05 pmAccording to the Wikipedia link JohanH posted earlier, it originates from the 1920. So long before the first DMM. If it came from General Radio, then I doubt it's based on European mains outlets, though it's possible they were both derived from a common source.If anything, I think the compatibility leads to dual banana plugs likethisbeing less common in Europe compared to the US.

author: JohanH
author_rank: Frequent Contributor
timestamp: January 04, 2024, 08:38:27 pm
content: Although without a source, the same wikipedia article is claiming there have been some controversy (and possibly some legalization) around the 19 mm banana spacing and European sockets:"In most European countries, the standard mains power receptacle will physically accept banana and even US-style "double banana" plugs (the standard US pin spacing of 3⁄4 inch (19 mm) is close enough to the mains plug spacing of about 19 mm, and the pin diameter is also compatible), leading to a risk of electrical shock. For this reason, throughout the European Union, audio amplifiers and loudspeakers that accept banana plugs must have plastic plugs in their sockets which can be manually removed by the user.[citation needed] The UK was included in the prohibition even though such mains sockets were not used there.[citation needed]"That might be one reason why more and more the safety type banana is preferred especially in Europe.

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2024, 08:47:47 pm
content: Quote from: alm on January 04, 2024, 08:04:31 pmWho says they’re less common? Anecdotally they seem quite common in electronics labs here.Quote from: JohanH on January 04, 2024, 08:38:27 pmSimilarly, is there any evidence of this claim, either?

author: JohanH
author_rank: Frequent Contributor
timestamp: January 04, 2024, 09:16:54 pm
content: Quote from: tooki on January 04, 2024, 08:47:47 pmNo

author: alm
author_rank: Super Contributor
timestamp: January 04, 2024, 10:02:18 pm
content: Quote from: tooki on January 04, 2024, 08:47:47 pmThe BNC to dual banana plug adapters are indeed very common, but I looked for a dual banana plug like the Pomona MDP-2 on Reichelt, a European distributor, and couldn't find it. Either as loose connector or as ready-made cable. On TME I could find the Pomona dual banana cables, but without any pictures. So it appears that the European manufacturers like Hirschmann and Staubli do not make them (except with sheathed banana plugs). Obviously they can be imported from the US and distributors like Farnell/E14 and Mouser are selling the Pomona connectors/leads in Europe.