EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: JohnPi on October 31, 2021, 11:58:23 pm
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I am working on some low voltage, medium current circuits (5 V, 20 A), and the standard Pomona 4 mm patch cords (which are extremely convenient) have too much resistance to allows my circuits to operate well. I am building some alternative cords using 10 awg silicone cables which are great (about 3 mΩ instead of 20 mΩ), but I don't have a good 4 mm plug for them -- one that handles the wire thickness and also makes a neat and strong connection.
Any suggestions ? Are stackable plugs available ?
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I made some with 8mm2 (8AWG) recently. I used piggyback plugs and soldered the cable into the socket.
"Not ideal", inflexible, ugly and hacky. Having said that, it did the job.
I've used these : https://www.altronics.com.au/p/p9281-red-stack-type-banana-plug/ (https://www.altronics.com.au/p/p9281-red-stack-type-banana-plug/) with 12AWG cable. Not ideal, but it just fits with a bit of gentle persuasion.
Edit : A 30 second digikey search : https://www.digikey.com.au/en/products/detail/mueller-electric-co/BU-3110410-4/7917533 (https://www.digikey.com.au/en/products/detail/mueller-electric-co/BU-3110410-4/7917533)
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At this current ad wire size perhaps switch to spade connectors and binding posts?
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https://www.eevblog.com/forum/testgear/banana-plug-and-big-wires/ (https://www.eevblog.com/forum/testgear/banana-plug-and-big-wires/)
Thick cable + stackable, no.
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I think RS does some 32A rated ones with piggyback plugs
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I think RS does some 32A rated ones with piggyback plugs
Rating (non-continuous?) of plug/socket only, not the cabling. The space they leave for cable is too small to practically carry those currents.
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I am working on some low voltage, medium current circuits (5 V, 20 A), and the standard Pomona 4 mm patch cords (which are extremely convenient) have too much resistance to allows my circuits to operate well. I am building some alternative cords using 10 awg silicone cables which are great (about 3 mΩ instead of 20 mΩ), but I don't have a good 4 mm plug for them -- one that handles the wire thickness and also makes a neat and strong connection.
Any suggestions ? Are stackable plugs available ?
Hirschmann has 32A leads with banana plugs. When I need to get more current from A to B I usually use 2 or more leads (with stackable plugs) in parallel but 4mm banana plugs top out at around 30A if you use good quality ones.
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The Hirschmann ones (what I was thinking about with my earlier comment about RS) are 2.5mm^2 (i.e. they might get a little warm, but will do 32A fine in free air), while there are also some (pricey) Mueller 10 AWG ones which are rated at 45A (35A @ 180C!!), e.g.: https://uk.rs-online.com/web/p/test-leads/1801286
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2.5mm²/32A also available from Staeubli (formerly MC).
They also supply test lead wire (ultra-flexible, PVC and Silicone) with up to 6mm² in their standard line and up to 95mm² under the 'Silistrom' label.
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At this current ad wire size perhaps switch to spade connectors and binding posts?
This would be my first thought, but would go one step further and suggest ring terminals on at least 1/4" studs.
Other approaches would be with connectors specifically designed for such loads. The battery connector designed for RC toys might be one approach. Or you might try Anderson Powerpole connectors: https://www.andersonpower.com/us/en/resources/PowerPoleResourcesPage.html. (https://www.andersonpower.com/us/en/resources/PowerPoleResourcesPage.html.) In fact I'd suggest looking into Powerpole first as you can find a lot of stuff built around the systems to support a power supply build.
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You probably want these: Superior Electric banana connector https://www.newark.com/superior-electric/pp250gwt/test-plug-pin-plug-250a-white/dp/98F3252 (https://www.newark.com/superior-electric/pp250gwt/test-plug-pin-plug-250a-white/dp/98F3252) The data sheet has "banana like" connectors up to 250A. The ones compatible with a 4mm banana connector are rated to 25A. These are solid brass and quite substantial. They have matching female connectors and double banana sockets.
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I ended up making my own. I took the metal core from (removed the plastic) some older or broken Pomona 4mm patch cords; I 3D-printed a replacement cover, but now with a wire entry diameter to fit the 10 AWG stranded silicone wire I have. By bending the stripped wire end 90 °, and tinning, I could solder it to the metal core, then press fit the 3D cover. It looks neat and clean; the resistance is about 1/10 the original wires, and I have the 'good' 4mm banana plug.
(http://[attachimg=1][attachimg=2])
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In the context of heavier currents (say, 20A to 32A) I came across several cases where wire or plug resistance could not be neglected (or even resulted in notable temperature rise).
Now using a 10mm2 cable (approx. 8AWG) with some banana plugs sold for loudspeaker purposes. Works very well. The cable is super flexible which is nice, although I might look more into different conductor materials in the future.
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Now using a 10mm2 cable (approx. 8AWG) with some banana plugs sold for loudspeaker purposes. Works very well. The cable is super flexible which is nice, although I might look more into different conductor materials in the future.
Interesting, did you add ferule to a cable (blue round part)?
I am looking at making 8-10mm2 cables for up to 40-60A currents, probably with RC style XT90 connectors.
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Interesting, did you add ferule to a cable (blue round part)?
Yes, that's a ferrule to ensure good contact and prevent damaging the strains of the wire.
In the comings days, I'll try to measure the resistance of this solution.
I am looking at making 8-10mm2 cables for up to 40-60A currents, probably with RC style XT90 connectors.
Using XT60 plugs for a number of (not so high current) applications and that works very well.
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I will have to check XT60 vs XT90. I think just the male metal part (without plastic) of XT90 ideally fits bigger sockets of power supply.
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I never disassembled an XT90 plug to use the pins otherwise. But some websites seem to report the pin diameter is 4.5mm. Also, they might be fairly short. So I have doubts whether this is a good replacement for a banana plug… (but perhaps some sockets have tolerance?). An experiment would tell…
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XT90 plug is for power supply sockets where regular standard 4mm jack is too loose. Mostly on higher current PSUs (from 20-30A and up). Either XT90 as a banana or spade crimp connector.
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XT90 plug is for power supply sockets where regular standard 4mm jack is too loose. Mostly on higher current PSUs (from 20-30A and up). Either XT90 as a banana or spade crimp connector.
I see, interesting. Out of curiosity, do you mean these PSU are designed to take an XT90 size pin and can you perhaps give an example)? Or do you mean that some PSUs simply have too loose a connection when used with a regular 4mm banana plug?
The higher current PSUs I found most often have screw terminals (for instance, BK Precision 9150), screw clamp connection (e.g. on Elektro Automatik EA PSI 9200-15), or M6 or M8 bolts on a metal rail or on a brass plate (various versions of EA PSI 9000 series). Some have safety connectors that take wires or spades but also 6mm plugs (such as AimTTi QPX series).
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XT90 plug is for power supply sockets where regular standard 4mm jack is too loose. Mostly on higher current PSUs (from 20-30A and up). Either XT90 as a banana or spade crimp connector.
Out of curiosity, do you mean these PSU are designed to take an XT90 size pin and can you perhaps give an example)? Or do you mean that some PSUs simply have too loose a connection when used with a regular 4mm banana plug?
I mean PSUs with loose (wide internal diameter) banana screw terminals. These just happen to work (but not designed) well with XT90 internal part as substitution for banana connector. For example, Gophert CPS3220, see video https://youtu.be/hX5xtOvAE4I?t=540
I am not certain what higher diameter socket is supposed to accept at >20A currents :-//
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I mean PSUs with loose (wide internal diameter) banana screw terminals. These just happen to work (but not designed) well with with XT90 internal part as substitution for banana connector.
Thanks for the reply. I have not come across this problem yet with my own PSUs, but will keep it in mind if I ever encounter it.
PS. Working with my son on drone motors, I came across the fact that these folks use 3.5mm jacks (!). Had to buy a bunch of them. There are too many standards ;-)
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Search amazon for "4mm cross bullet connector". e.g.: https://www.amazon.com/dp/B07ZT58XNN/ (https://www.amazon.com/dp/B07ZT58XNN/)
These are heavy connectors that can take abundant current. They come as male/female sets so you could cobble together a stackable plug if that's what you want. They require a closer tolerance socket than the normal spring type banana plugs, so they might not fit tightly into absolutely every banana jack on your bench.
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Not compatible with standard banana plugs, and quite expensive: https://www.specialtyproducttechnologies.com/superiorelectric/products/electrical-connectors/supercon-electrical-connectors (https://www.specialtyproducttechnologies.com/superiorelectric/products/electrical-connectors/supercon-electrical-connectors) and https://info.specialtyproducttechnologies.com/5-way-supercon-catalog-download (https://info.specialtyproducttechnologies.com/5-way-supercon-catalog-download)
I found them very useful at high current levels, even at frequencies around 10 MHz.
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Search amazon for "4mm cross bullet connector". e.g.: https://www.amazon.com/dp/B07ZT58XNN/ (https://www.amazon.com/dp/B07ZT58XNN/)
These are heavy connectors that can take abundant current. They come as male/female sets so you could cobble together a stackable plug if that's what you want. They require a closer tolerance socket than the normal spring type banana plugs, so they might not fit tightly into absolutely every banana jack on your bench.
Thank you for providing that search term, I was struggling the other day to find what the good one piece split pin type are called. Seems "cross" and/or "high current" are the key terms.
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Here's the final result and the source files are attached.
[attach=1][attachimg=1][attachurl=2]
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These are Pomona 5000 Volt 36 in banana patch cords,do you think they would be low enough resistance?
https://fairradio.com/product/rj-5031-3y/
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With such a high voltage rating, most of the diameter is going to be insulation. So the actual copper will be rather less then with standard test leads.
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If you look for high voltage or high current test leads connectors in good quality, take a look at the Swiss company:
Stäubli / MC / Multicontact
https://www.staubli.com/en/connectors/electrical-connectors/ (https://www.staubli.com/en/connectors/electrical-connectors/)
In my experience they are one of the best.
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Maybe there is room to use the standard molex mini-fit connectors used by video cards?
Being mass produced headers, you can buy them cheap, and you can also buy the connectors cheap, same for crimping tools.
For example use a pci-e 6 or 8 pin connector, either right angle or straight up ... you have 3 awg18/awg16 pairs of wires for low voltage drop and contact resistance, and you can get mass produced 6/8 pin pci-e extensions cables or make your own.
example: https://www.digikey.com/en/products/detail/molex/0455580003/3311349 (https://www.digikey.com/en/products/detail/molex/0455580003/3311349)
Could have two side by side and thick traces connecting each row for "pass through" ... first is input, second is output ... or the other way around ...