Author Topic: Test leads for power supply, make or buy?  (Read 16103 times)

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Offline broderp

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Test leads for power supply, make or buy?
« on: April 24, 2015, 12:09:42 am »
I'm realizing with my new supply that the test leads I have probably won't cut it.  They drop voltage and I'm not to thrilled about this.  (5VDC set, only getting 4.6~4.7 to the project)

So this being my first real supply (RIGOL DP832) I'm curious as to what leads you guys use and/or if I would be better off making my own? 

I liked to have the dual banana type to either alligator or small grabbers. 

I'm a bit surprised at how much test leads cost.  I have to wonder it it's all brand name hype or if dropping $25 on a simple set of leads is common.    :-//

 
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Offline JBaughb

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Re: Test leads for power supply, make or buy?
« Reply #1 on: April 24, 2015, 12:16:57 am »
Fairly inexpensive on eBay.
 

Offline 128er

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Re: Test leads for power supply, make or buy?
« Reply #2 on: April 24, 2015, 12:49:33 am »
Back then when I needed a sortiment of test leads, I ordered a couple of insulated alligator clips and mini grabbers. And heat resistant silicone leads in 0,5 mm² and 1.5 mm².

I haven't looked for ready available test leads or compared the price. But I think my solution was not very cheap. But i do not regret it. I could assemble the test leads in a way that they fit my needs.

Particularly I can highly recommend these things here. Very practical:

http://uk.farnell.com/wago/215-311/plug-4mm-cage-clamp-black/dp/844019
 

Offline Richard Crowley

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Re: Test leads for power supply, make or buy?
« Reply #3 on: April 24, 2015, 12:52:01 am »
Wow, that seems like a lot of drop.
Of course, you did not mention how much current you are using there.
You also did not mention the wire gauge of the test leads.
So, without those crucial pieces of information we are unable to really advise anything.
Have you actually measured the voltage at each end of the test leads?  Both positive and negative?
Have you measured the resistance of the test leads?
Are you using decent banana plugs or some kludgy cheapie Chinese thing?
How are the test leads connected to the load?  Alligator clips?
 

Offline Richard Crowley

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Re: Test leads for power supply, make or buy?
« Reply #4 on: April 24, 2015, 01:07:20 am »
Frankly, I have several leads made from ordinary "lamp-cord" (or "zip-cord") with stacking bananas on one end and proper alligator clips (or whatever) on the other end.  The wire gauge is nice and big for loads of many amps.  And the "twin" cable reduces the mess on the bench top.
 

Offline broderp

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Re: Test leads for power supply, make or buy?
« Reply #5 on: April 24, 2015, 01:13:30 am »
Wow, that seems like a lot of drop.
Of course, you did not mention how much current you are using there.
You also did not mention the wire gauge of the test leads.
So, without those crucial pieces of information we are unable to really advise anything.
Have you actually measured the voltage at each end of the test leads?  Both positive and negative?
Have you measured the resistance of the test leads?
Are you using decent banana plugs or some kludgy cheapie Chinese thing?
How are the test leads connected to the load?  Alligator clips?

Have you actually measured the voltage at each end of the test leads?  Both positive and negative?  No
Have you measured the resistance of the test leads? No
Are you using decent banana plugs or some kludgy cheapie Chinese thing? Old Pomona and generic from school
How are the test leads connected to the load?  Alligator clips? Mini grabber and or alligators

I know I was a bit vague.  The leads I have are Pomona mini grabbers I've had since getting my AAS degree back in 96.  I also have several banana leads to alligator, but they are all old and I bought them when in school as part of the course work I was taking.  (I don't know the actual cost or what I truly paid for them, the cost of the class included kits, books etc..)

My newer DMM, a Tripplet 9045 measures the a 5VDC set point (5.01VDC actual) as 4.993VDC so I'm almost certain is the leads or circuit.  I threw together some very simply circuits with LEDS and resistors, so I was only pulling a few mA, .0125

I don't have anything substantial in the way of test leads and I'd like to put together a kit to keep with the supply.  It doesn't help that I really don't have a true test load.  So I'm looking for recommendations.

Cheers.
« Last Edit: April 24, 2015, 01:16:25 am by broderp »
 

Offline broderp

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Re: Test leads for power supply, make or buy?
« Reply #6 on: April 24, 2015, 01:27:46 am »
Frankly, I have several leads made from ordinary "lamp-cord" (or "zip-cord") with stacking bananas on one end and proper alligator clips (or whatever) on the other end.  The wire gauge is nice and big for loads of many amps.  And the "twin" cable reduces the mess on the bench top.

I'm killer with a solder iron, I have no problem making leads.  I wonder what the cost advantage vs. performance (premade) would be. 

Can you comment on the cheaper banana plugs such as these?  Will these with good wires and strong alligator or grabbers work in you opinion?
http://www.amazon.com/Hosa-Technology-BNA100-Banana-Connector/dp/B000068OAY/ref=sr_1_2?s=electronics&ie=UTF8&qid=1429841979&sr=1-2&keywords=dual+banana+plug

Good quality mini grabbers are hard to find for a good  price. Not sure of the quality of these :-\ 
http://www.amazon.com/Banana-Mini-Grabber-Deluxe-Version/dp/B00KC2PCV8/ref=sr_1_1?s=electronics&ie=UTF8&qid=1429838554&sr=1-1&keywords=Mini+Grabbers

Even harder to find are good quality mini grabbers that I can use with my own wires to make a test lead. I can find generic cheap ones, but don't know how long it will hold up.
http://www.amazon.com/Clips-Grabber-Probe-Digital-Multimeter/dp/B00W1CKGHC/ref=sr_1_18?s=electronics&ie=UTF8&qid=1429838554&sr=1-18&keywords=Mini+Grabbers

These are much more expensive than home made, but are they worth it?
http://www.amazon.com/Heavy-Duty-12-AWG-Alligator/dp/B00PDUELBG/ref=sr_1_3?s=electronics&ie=UTF8&qid=1429838790&sr=1-3&keywords=Test+leads+for+power+supply
 

Online xrunner

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Re: Test leads for power supply, make or buy?
« Reply #7 on: April 24, 2015, 01:42:15 am »
So this being my first real supply (RIGOL DP832) I'm curious as to what leads you guys use and/or if I would be better off making my own? 

Make your own.

I repeat - make your own.

As you can see in the pic below, you cannot see how well the leads are made on the inside unless you cut them open with a knife as I did. I do NOT trust any test leads coming from China unless you can unscrew the outside cover and inspect them. Unfortunately, most are sealed with the plastic.

And to repeat myself again -make your own!


I am a Test Equipment Addict (TEA) - by virtue of this forum signature, I have now faced my addiction
 

Offline mtdoc

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Re: Test leads for power supply, make or buy?
« Reply #8 on: April 24, 2015, 01:42:44 am »
I recommend the leads from forum member Frankie's eBay store

Or make your own! :D
 

Offline john_p_wi

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Re: Test leads for power supply, make or buy?
« Reply #9 on: April 24, 2015, 01:47:27 am »
What is yoiur purpose and expected current?  12ga?  Rather beefy, if you deal with bread boards the thickness of the cable will make it hard to work with, additionally 6 feet is rather long.  Again, what is the purpose?  Generally bench supply cables are 18 to 24 inches.

I don't like the cheap ebay stuff, the bananas never fit right IMO.  Look at Pamona on Mouser, you'll find that their assembled cables are not much more than the individual pieces and assembling the cables yourself. 
 

Offline Richard Crowley

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Re: Test leads for power supply, make or buy?
« Reply #10 on: April 24, 2015, 01:56:02 am »
If you are dropping 0.4V at 12.5mA, that means your leads are 32 ohms!   :scared:
That is HORRIBLE!  Throw out that junk and make some proper cables.

I can't think of ANY reason store-bought banana test leads would be "better" than home-made ones.
And $30 for a pair of banana to alligator leads should be a criminal offense.

OTOH, using those little "grabbers" for applying power to a circuit just leaves me cold. I wouldn't do it.
 

Offline rx8pilot

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Re: Test leads for power supply, make or buy?
« Reply #11 on: April 24, 2015, 02:13:52 am »
I almost always make my own. The reason is that I want to know and control the quality of the lead. I have purchased pre-made leads that had me chasing my tail because of variations in quality. I also like to have specific lengths, colors, ampacity, grabbers, clips, etc. I hate making them, but hate being surprised by lame leads even more.

Pomona is a typical source for bananas and clips. I have a few reels of test lead wire which is very fine strand and thick jacket wire. When possible, I get the set screw right angle bananas because they are so easy.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline mtdoc

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Re: Test leads for power supply, make or buy?
« Reply #12 on: April 24, 2015, 02:51:13 am »
Most of my leads I've made myself.  Hobbyking is a good source for larger gauge silicone insulated wire at a good price.  But of the leads I have bought, the ones from Franky's eBay store have been top notch - equal or better than the few Pomona leads I have and nothing like other cheap eBay leads I've seen.
 

Offline iloveelectronics

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Re: Test leads for power supply, make or buy?
« Reply #13 on: April 24, 2015, 03:21:37 am »
I recommend the leads from forum member Frankie's eBay store

Or make your own! :D

Thanks for the recommendation!

Martin did a couple of reviews on my test leads some time ago : 
https://youtu.be/6JmynSaTA3w?t=13m0s
https://youtu.be/0Wc703NHQH4?t=14m0s
https://youtu.be/dzyNSxTTSRw?t=8m56s
My email address: franky @ 99centHobbies . com
My eBay store: http://stores.ebay.com/99centhobbies
 

Offline bitwelder

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Re: Test leads for power supply, make or buy?
« Reply #14 on: April 24, 2015, 05:06:21 am »
My newer DMM, a Tripplet 9045 measures the a 5VDC set point (5.01VDC actual) as 4.993VDC so I'm almost certain is the leads or circuit.  I threw together some very simply circuits with LEDS and resistors, so I was only pulling a few mA, .0125
Such a voltage drop for such a small current? Hmm...
Did you try to increase the current? You should see an even more dramatic voltage drop, if it's coming from the leads/grabbers.
BTW, I hope the mini-grabbers are in good conditions, i.e. not oxidized.
 

Offline Jeroen3

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Re: Test leads for power supply, make or buy?
« Reply #15 on: April 24, 2015, 05:24:57 am »
Buy some Genuine SKS (Hirschmann). They're good for generations.
http://www.sks-kontakt.de/
 

Offline Dago

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Re: Test leads for power supply, make or buy?
« Reply #16 on: April 24, 2015, 06:23:55 am »
I made my own lab cables and am really happy with them https://twitter.com/DGKelectronics/status/475986171500453888

I used Deltron banana connectors which were quite nice, and silicone wire from ebay that was very decent. The cables from ebay tend to be rubbish and pre-made cables from Farnell or other vendor like that are really expensive.
Come and check my projects at http://www.dgkelectronics.com ! I also tweet as https://twitter.com/DGKelectronics
 

Offline VK5RC

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Re: Test leads for power supply, make or buy?
« Reply #17 on: April 24, 2015, 06:44:33 am »
+1 For make your own,  can get length right.
+1 For using franky's stuff,  great quality and price.
Whoah! Watch where that landed we might need it later.
 

Offline ModemHead

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Re: Test leads for power supply, make or buy?
« Reply #18 on: April 24, 2015, 12:41:06 pm »
Over the years I've also learned it's best to make your own leads.  If you get some good quality banana plugs with set-screws, you can re-purpose them quickly and easily for different projects, to offset the higher cost.  I'm a big fan of Pomona dual banana plugs (MDP series) and try to keep some on hand, the set-screws will accommodate about anything from hook-up wire to lamp cord, and also component leads.
 

Offline kayvee

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Re: Test leads for power supply, make or buy?
« Reply #19 on: April 24, 2015, 12:51:37 pm »
Buy some Genuine SKS (Hirschmann). They're good for generations.
http://www.sks-kontakt.de/

Indeed these are built like the proverbial brick dunny  ;D

I have a number of sets kicking around in regular use since the 80's and still going strong.
 

Offline Richard Crowley

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Re: Test leads for power supply, make or buy?
« Reply #20 on: April 24, 2015, 01:03:51 pm »
Can you comment on the cheaper banana plugs such as these?  Will these with good wires and strong alligator or grabbers work in you opinion?
http://www.amazon.com/Hosa-Technology-BNA100-Banana-Connector/dp/B000068OAY/ref=sr_1_2?s=electronics&ie=UTF8&qid=1429841979&sr=1-2&keywords=dual+banana+plug
The traditional design with the solid metal core and the four length-wise springs are the prefered design. Those newer things with plastic parts and dodgy spring design are questionable IME.

OTOH, I'm not that big on the DUAL kind of banana plugs because it limits you flexibility to connect ONLY to the proper-spaced pair.

This is my favorite kind of Pomona banana plug....

 

Offline robrenz

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Re: Test leads for power supply, make or buy?
« Reply #21 on: April 24, 2015, 01:20:59 pm »

Offline ModemHead

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Re: Test leads for power supply, make or buy?
« Reply #22 on: April 24, 2015, 02:10:04 pm »
OTOH, I'm not that big on the DUAL kind of banana plugs because it limits you flexibility to connect ONLY to the proper-spaced pair.
Yeah it's a pain when the power supply sticks the earthing jack right in the middle.

This is my favorite kind of Pomona banana plug....
Pomona 1825 series.  I like to keep those around also.  Solid contact, stacking design, set-screw, and very re-useable.
 

Offline Richard Crowley

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Re: Test leads for power supply, make or buy?
« Reply #23 on: April 24, 2015, 03:16:28 pm »
Yeah it's a pain when the power supply sticks the earthing jack right in the middle.
Or if you want to take the power connection and temporarily ground it to discharge the circuit, etc.

Quote
Pomona 1825 series.  I like to keep those around also.  Solid contact, stacking design, set-screw, and very re-useable.
I really prefer the kind like that with the FIXED springs.


The kind with the loose, rotating spring just adds another layer of (not very good) pressure contact to the circuit, and I don't really like that because it increases the contact resistance and reduces reliability.
 

Offline broderp

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Re: Test leads for power supply, make or buy?
« Reply #24 on: April 24, 2015, 03:26:13 pm »
I recommend the leads from forum member Frankie's eBay store

Or make your own! :D

Thanks for the recommendation!

Martin did a couple of reviews on my test leads some time ago : 
https://youtu.be/6JmynSaTA3w?t=13m0s
https://youtu.be/0Wc703NHQH4?t=14m0s
https://youtu.be/dzyNSxTTSRw?t=8m56s

Wow...I'm liking what I see......I'm going to have to hop on over to your store and check this out.   Looks like you have the type(s) and quality I can use.   ^-^

Darn....My employer apparently does not like your ebay store, so I am being blocked.  Do you have an actual website so that I can see the items you have for sale and do some comparison shopping?  ::)  The YouTube video's look very convincing.  If the price comes in where I need, I may be contacting you.   :-+
« Last Edit: April 24, 2015, 03:44:51 pm by broderp »
 


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