Test leads for power supply, make or buy? - Page 1
Forum section: electronics / beginners

author: broderp
author_rank: Regular Contributor
timestamp: April 24, 2015, 12:09:42 am
content: 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.

author: JBaughb
author_rank: Regular Contributor
timestamp: April 24, 2015, 12:16:57 am
content: Fairly inexpensive on eBay.

author: 128er
author_rank: Regular Contributor
timestamp: April 24, 2015, 12:49:33 am
content: 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

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 24, 2015, 12:52:01 am
content: 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?

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 24, 2015, 01:07:20 am
content: 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.

author: broderp
author_rank: Regular Contributor
timestamp: April 24, 2015, 01:13:30 am
content: Quote from: Richard Crowley on April 24, 2015, 12:52:01 amHave you actually measured the voltage at each end of the test leads? Both positive and negative?NoHave you measured the resistance of the test leads?NoAre you using decent banana plugs or some kludgy cheapie Chinese thing?Old Pomona and generic from schoolHow are the test leads connected to the load? Alligator clips? Mini grabber and or alligatorsI 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, .0125I 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.

author: broderp
author_rank: Regular Contributor
timestamp: April 24, 2015, 01:27:46 am
content: Quote from: Richard Crowley on April 24, 2015, 01:07:20 amI'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+plugGood quality mini grabbers are hard to find for a good price. Not sure of the quality of thesehttp://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+GrabbersEven 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+GrabbersThese 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

author: xrunner
author_rank: Super Contributor
timestamp: April 24, 2015, 01:42:15 am
content: Quote from: broderp on April 24, 2015, 12:09:42 amMake 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!

author: mtdoc
author_rank: Super Contributor
timestamp: April 24, 2015, 01:42:44 am
content: I recommend the leads from forum member Frankie'seBay storeOr make your own!

author: john_p_wi
author_rank: Regular Contributor
timestamp: April 24, 2015, 01:47:27 am
content: 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.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 24, 2015, 01:56:02 am
content: If you are dropping 0.4V at 12.5mA, that means your leads are 32 ohms!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.

author: rx8pilot
author_rank: Super Contributor
timestamp: April 24, 2015, 02:13:52 am
content: 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.

author: mtdoc
author_rank: Super Contributor
timestamp: April 24, 2015, 02:51:13 am
content: 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.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: April 24, 2015, 03:21:37 am
content: Quote from: mtdoc on April 24, 2015, 01:42:44 amThanks for the recommendation!Martin did a couple of reviews on my test leads some time ago :https://youtu.be/6JmynSaTA3w?t=13m0shttps://youtu.be/0Wc703NHQH4?t=14m0shttps://youtu.be/dzyNSxTTSRw?t=8m56s

author: bitwelder
author_rank: Super Contributor
timestamp: April 24, 2015, 05:06:21 am
content: Quote from: broderp on April 24, 2015, 01:13:30 amSuch 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.

author: Jeroen3
author_rank: Super Contributor
timestamp: April 24, 2015, 05:24:57 am
content: Buy some Genuine SKS (Hirschmann). They're good for generations.http://www.sks-kontakt.de/

author: Dago
author_rank: Frequent Contributor
timestamp: April 24, 2015, 06:23:55 am
content: I made my own lab cables and am really happy with themhttps://twitter.com/DGKelectronics/status/475986171500453888I 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.

author: VK5RC
author_rank: Unknown
timestamp: April 24, 2015, 06:44:33 am
content: +1 For make your own, can get length right.+1 For using franky's stuff, great quality and price.

author: ModemHead
author_rank: Frequent Contributor
timestamp: April 24, 2015, 12:41:06 pm
content: 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.

author: kayvee
author_rank: Regular Contributor
timestamp: April 24, 2015, 12:51:37 pm
content: Quote from: Jeroen3 on April 24, 2015, 05:24:57 amIndeed these are built like the proverbial brick dunnyI have a number of sets kicking around in regular use since the 80's and still going strong.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 24, 2015, 01:03:51 pm
content: Quote from: broderp on April 24, 2015, 01:27:46 amThe 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....

author: robrenz
author_rank: Super Contributor
timestamp: April 24, 2015, 01:20:59 pm
content: All from the same old threadMy favorite jacksMy favorite wireMy favorite grippers

author: ModemHead
author_rank: Frequent Contributor
timestamp: April 24, 2015, 02:10:04 pm
content: Quote from: Richard Crowley on April 24, 2015, 01:03:51 pmYeah it's a pain when the power supply sticks the earthing jack right in the middle.Quote from: Richard Crowley on April 24, 2015, 01:03:51 pmPomona 1825 series. I like to keep those around also. Solid contact, stacking design, set-screw, and very re-useable.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 24, 2015, 03:16:28 pm
content: Quote from: ModemHead on April 24, 2015, 02:10:04 pmOr if you want to take the power connection and temporarily ground it to discharge the circuit, etc.QuoteI 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.

author: broderp
author_rank: Regular Contributor
timestamp: April 24, 2015, 03:26:13 pm
content: Quote from: iloveelectronics on April 24, 2015, 03:21:37 amWow...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.

author: nowlan
author_rank: Frequent Contributor
timestamp: April 24, 2015, 03:37:43 pm
content: Slightly off topic:I am looking for shrouded 4mm plugs. I want to make a a box similar tothis.I dont trust the stackable connectors with mains voltage. I have seen a few brands and styles, by Mueller and silvertronic. Not sure if I want 90' for strain relief. Unfortunately they seem to come in packs of 2 or 5.

author: Jeroen3
author_rank: Super Contributor
timestamp: April 24, 2015, 05:12:04 pm
content: Try the SLS 10, they fit regular 4mm banana plugs, while still keeping it shrouded.http://tinyurl.com/nk3ptnj

author: rx8pilot
author_rank: Super Contributor
timestamp: April 24, 2015, 05:15:37 pm
content: Quote from: Richard Crowley on April 24, 2015, 01:03:51 pmThose Pomona's are my go-to choice and they have be re-purposed dozens of times. Usually keep 15-20 on hand to rig up a test configuration. The dual plugs have been handy since I built a custom IO panel for my HP power supplies and electronic loads. The singles get used for meters and the duals get used for power.Either way, as much as I don't like making them, I would not do it any other way. I have the perfect compliment of leads for the type of work I do and I have enough spare parts to make anything on the fly.

author: john_p_wi
author_rank: Regular Contributor
timestamp: April 24, 2015, 05:28:02 pm
content: Quote from: Richard Crowley on April 24, 2015, 01:03:51 pm^^^ Yes ^^^If you build your own, use these Pomona or similar Pomona. On some of the cheap knock offs, the "springs" are higher up towards the wire connection point - thusly they do not make good contact towards the tip. This is important IF the mating jack is somewhat shallow, I noticed it with a BK 2709 DMM, but not a problem with Flukes.I hate cheap crap that doesn't work.

author: rx8pilot
author_rank: Super Contributor
timestamp: April 24, 2015, 05:48:52 pm
content: Quote from: john_p_wi on April 24, 2015, 05:28:02 pmSaving money is an art. Buying cheap stuff is often the most expensive option.

author: broderp
author_rank: Regular Contributor
timestamp: April 24, 2015, 07:47:09 pm
content: Quote from: Richard Crowley on April 24, 2015, 01:03:51 pmI agree, I like Pomona, but they are very pricey. They would be on my short list if money was no object. I like these:http://www.amazon.com/Pomona-3786-C-36-Minigrabber-Multi-Stacking-Double/dp/B00COC9U1C/ref=sr_1_11?ie=UTF8&qid=1429904501&sr=8-11&keywords=pomona+banana+plugBut MAN, this seems like a total rip off..Even the connectors you like are pricey for just the banana end:http://www.amazon.com/Pomona-1825-02-Solderless-Stackup-Banana/dp/B00COBUR2Y/ref=sr_1_1?ie=UTF8&qid=1429904501&sr=8-1&keywords=pomona+banana+plugI know, you get what you pay for, but I don't always believe cost equals the best quality...

author: bookaboo
author_rank: Frequent Contributor
timestamp: April 24, 2015, 08:27:50 pm
content: Quote from: Richard Crowley on April 24, 2015, 03:16:28 pmIs that screw on the side connected to the pin?

author: broderp
author_rank: Regular Contributor
timestamp: April 24, 2015, 08:48:12 pm
content: QuoteIn my limited experience, mostly with fairly cheap banana's YES, the screw on the side is what you use to secure the wire. The metal part of the pin is usually all one part.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 24, 2015, 08:51:24 pm
content: Quote from: bookaboo on April 24, 2015, 08:27:50 pmYes. I wasn't trying to endorse those designs, only illustrate the fixed longitudinal spring design vs. the floating round spring.If I had to use those with a screw in the side, I would probably put heat-shrink tubing over it after assembly.And remember to never use them for high voltages.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: April 25, 2015, 02:22:38 am
content: From a safety viewpoint I dislike exposed connections, grub/set screws etc. and prefer shrouded connectors.Yes I've got leads that don't comply with my preferences and when testing much is exposed to careless hands.Without being too paranoid I prefer to avoid accidental shorts even with low power kit. Perhaps it's my own clumsiness but I also prefer to use the shortest probes/connectors I can which place the least strain on the parts connected to.

author: john_p_wi
author_rank: Regular Contributor
timestamp: April 25, 2015, 05:06:33 am
content: Quote from: broderp on April 24, 2015, 07:47:09 pmMan whom ever set those Amazon prices is on crack. As I mentioned before, check out Mouser:Buck 85 for singles all day long:http://www.mouser.com/ProductDetail/Pomona-Electronics/1825-2/?qs=sGAEpiMZZMsQWb9Zho8SKjolHJYGwbfH

author: broderp
author_rank: Regular Contributor
timestamp: April 25, 2015, 03:12:58 pm
content: Quote from: john_p_wi on April 25, 2015, 05:06:33 amPerhaps not all Pomona banana plugs are equal?http://www.mouser.com/ProductDetail/Pomona-Electronics/1825-02/?qs=sGAEpiMZZMtW7Xd10NdmuJ0hw%2fJ5i2UGkOyIZt8O6Ao%3dI'll see if I can find them in red as well. The data sheet states the "-" number (1825-X) is the color. 2 is red, but the image shows black. Not a big deal I just want to be sure.Thanks for showing me an alternate source. Hope shipping wont be hatefulEDIT: Never mind, the link above is for TWO, one red and one black.EDIT: Cheapest shipping option is $5 Six pair would break down to costing about $2.37 each. STILL MUCH CHEAPER THAN AMAZON. lolI've been communicating with Frankie via email. If he can put together a reasonable priced option to do what I need, I think I will try his leads out first.If I need to make them, I will get these Pomona's and start to research wire and clips and grabbers for the other end. Just a lot of work I'd rather not do at this point.

author: nanofrog
author_rank: Super Contributor
timestamp: April 25, 2015, 09:47:22 pm
content: Quote from: broderp on April 25, 2015, 03:12:58 pmIf the P/N is correct as per the color code per what you're after on singles (1825-1 for BLK or 1825-2 for RED), you'll get the correct color you're after.Quote from: broderp on April 25, 2015, 03:12:58 pmThey'll charge you the real rate they pay (same for other mainstream component distributors), so figure ~$7.00 or so for a handful of banana plugs. Add enough to bring your order up to say a $50+ order, and the shipping is much cheaper per part (i.e. shipping may still only come in at $8 - $9 for ~4x the order cost of just the banana plugs).

author: robrenz
author_rank: Super Contributor
timestamp: April 26, 2015, 12:38:02 am
content: Quote from: broderp on April 25, 2015, 03:12:58 pmI listed links for excellent Pomona wire and grabbers in post 21. I realize it may be more money than you want to spend right now. Those parts listed turn out to be $4.32 for a 36" lead with Pomona wire and grabbers.

author: broderp
author_rank: Regular Contributor
timestamp: April 28, 2015, 01:09:01 am
content: Quote from: robrenz on April 26, 2015, 12:38:02 amI've bookmarked that post for future reference. Thanks!