Ask Hackaday: Bitten by the Crocodile Clip

I have a love/hate relationship with the crocodile clip. Nothing is so quick to lash together a few half-baked prototype boards on your desk, but nothing ends up in such a tangle so quickly, either. I love the range of pretty colors that crocodiles come in, as well as the easy ability to just clip on to the side of a PCB, or any old loose wire. But they come loose, they can have intermittent contacts, and we’re not even sure if there is such a thing as a current rating for them.

When [WarriorRocker] wrote in asking what we use instead of crocodile clips, he included a photo that sent a chill down my spine, from a review of some clips on Amazon. I’ve seen this one in real life. And what’s worse is the one with the loose wires that sometimes make contact with the spring-clip body and sometimes not.

After an hour-long debugging session about twelve years ago now, such an intermittent croc caused us to make a lifelong vow. All of our croco-clips have been disassembled, manually inspected, and many of them soldered together. When I buy new ones, I check them all before mixing them in with the known-goods. Even thinking about this now makes me want to pull back their little rubber booties just to make sure.

But intermittents are not the only source of trouble. How thick is the wire inside your crocs? Are you sure that it’s beefy enough to take the current you’re passing through it? Are you sure the pointy teeth are making enough contact with whatever you’re clipping them to? Of course not. How would you be?

So we’re passing [WarriorRocker]’s questions on to you. Do you have any rules of thumb for how much current to pass through crocodile clips? What do you clip them to and what do you avoid? How do you manage the tangle? Do you just trust them when they come from the factory or have you been bitten too? What alternatives have you considered, and how’s it working? Or is there some ultra-premium crocodile clip manufacturer out there that lets us trade off pain for mere money?

69 thoughts on “Ask Hackaday: Bitten by the Crocodile Clip

  1. Cheap crocodile/banna plug cables have also another flaw: the internal conductors do have very small cross-section (a few hair-like thin copper wires), despite the outer diameter of wire is 2-3mm. Those tend to have resistance in order or 1Ohm per meter, causing substantial voltage drops and the insulation liquefies at currents above 2A. It’s OK for small currents, though. It’s pretty hard to find really good cable at reasonable price.
    I bought some 4mm banana plugs, crocodile clips and spool of red and black wire (1,5mm cross section) and spent hour soldering it together – now I have some solid and reliable cables.

    1. I have vaporized the insulation of of the “heavy duty” variety using it to shunt across a thermal fuse to test a coffee pot heater. You think heavy duty would imply nonflaming up to at least 10A.

      1. Funny, I put about 8A through a cheap radio shack alligator clip lead and it was fine, but I’ve encountered chintzy ones too… Is there a difference between an alligator clip and a crocodile clip?

        1. Funny you should mention that. “We”, as in, everyone I have known or sold them, call them “alligator clips”.
          But, and here is where things get interesting, there is a “crocodile clip”. It is a bigger version. Most people have probably used them and not known what the true name is. an example, if you use various probes that have the large clip for ground or common, then that is the “croc clip”. Many differential probes use them, such as differential probes.
          I learned this years ago, these clips simply slide of the wire and can be replaced with other attachments. They become easily lost or misplaced when equipment is shared, say in a lab or production place, where one piece of equipment is shared by many. anyway, I had to go through and repair and/or replace this equipment and found several probes missing these croc clips. When I searched for alligator clips, I got the standard ones you see above. Going through the manuals, I found the larger missing ones referred to as crocodile clips. That’s what I ordered them under, many companies know exactly what you’re talking about.

      1. This is exactly what I do, having found the very same problem as shown in the photos. Very thin conductor, not soldered to the clip but just pressed against it by the crimp. Easily measurable resistance (with just a DMM) of a few Ohms. So I bought good quality silicone-insulated wire (from radio-control model supplier) and rebuilt them, with solder. Also found silicone-insulated wire in the ten resistor-colour-code colours, but haven’t tried it yet. Need to find croc clip covers in orange, violet, etc.

        1. If you find these, please buy a ton and open a Tindie store. :)

          I’ve been using the silicone wire from R/C hobby suppliers, mostly 18AWG, since that seems to be a good compromise between flexibility and current handling. Sticking Pomona 1825 stackable bananas on the ends, which are available in more colors but min qty 10.

  2. There is absolutely nothing worse than flaky intermittent test gear! I bought some cheap test clips a while ago. And indeed they were cheap in spades! Some miserable excuse for wire with a few strands of copper and just folded back on the insulation and sort of crimped. But the clips themselves are OK, so I get some decent wire and do the soldering to rebuild them. You may as well just buy a few big packs of alligator clips and build your own test clips. I am not sure if that is cheaper than just buying test wires or not.

    So, no I don’t even check them. I just immediately rebuild them. If you have any cheap clip wires, just chop them all in half immediately so you aren’t tempted to waste time using them like I did ….. before I learned.

  3. I think everyone has at least one story centred around these damned clips. A few of the places I worked had an electroplating department which I supported as a chemist/metallurgist, and they used larger examples of these at almost every step. All sorts of fun would occur in the intersection of chemical attack on hidden parts of the clip from the very corrosive solutions and the very high amperages used in certain types of plating.

  4. amazon and ebay; I tried buying some ‘shorts’ but really got a bunch of ‘opens’ ;( yeah, the clips that should have been close to 0 were closer to infinity. I stopped buying chinese jumpers (the current cheap ‘arduino style’ breadboard male-male jumpers have also been ‘opens’ rather than ‘shorts’, more times than I would have liked. sigh…).

  5. I bough a bunch of bare alligator clips (never heard of crocodile clips, must be a larger cousin. My hippie dad called them roach clips sometimes, but I digress). I soldered a bunch up and use those. If I need more, I will solder some more.

    How much current? Depends on the wire I guess.. I’m doing 12v or less projects and I’ve haven’t even thought about it.

    1. I don’t understand the whole roach business. Why didn’t people just roll a piece of cardboard into a tube and insert that in the butt of the joint for something to hold on to? That’s how I’ve seen it done.

      To think, a whole generation of people exhibiting so little innovation that they smoked their joints “hairy-ass” and had to use alligator clips to save weed.

  6. I make my own cables and have never had much trouble. I have several dozen alligator clips of different sizes and shapes, allowing me to solder up any cable I need in just a few minutes. I tend to use #16 or #18 wire for my cables, so current carrying capacity has never been an issue with my various projects. I can always make up a set using #12 wire if I find that the #16 is insufficient for something.

  7. I try not to use them at all, but they are so handy I keep them around. I haven’t bought or used commercially made assembly in years. They all cost more than parts and I have to remake them anyway. If I have it on hand, I use test lead wire (heavy ultraflexible insulation over moderate sized fine stranded conductors) which is usable to 10A reliably, and 20A for a good period. I think the lead I use is about 16Ga (1.2mm^2). Red and black are usually on hand. Other colors mean going to stranded hookup wire, which is less flexible, though smaller.

    I have a stock of assorted clips, and bought a bag (500) of medium sized (15mm jaw length, serrated) about 20 years ago that I have not yet gone through. I just color the hoods with vinyl tape for ID. These are ok up to about 5A, and don’t cook until about 10A or more, as long as the wired jaw has several points in good contact. The other jaw might as well be made of acetyl for all of the current carrying capacity it adds.

    I also use telephone clips (end grab with insulation piercing pins), small smooth jaw clips, several flavours of hook, and probes (also bought a pack of them a number of years ago-I think is was 10 in the box?). I also keep a few of the larger sizes on hand. The biggest I have is the size of a small jumper cable clamp, and work about as well (not very, for significant current over significant time) and has a bug-bolt connector for 5mm (4Ga) wire. Handy for grabbing bus bars, but I don’t trust the current capacity at the working end. Many of these I inherited (some pre-war or war surplus), and others picked up at swap meets and yard sales.

    Then I could get into the welding and specialty clamps, all of which do their jobs well, but are out of the context of the discussion.

    1. Telephone clips (so named because the end is formed to clip onto a 66-style punchdown block) are awesome. I seek them out at hamfests to make sets of ultimate helping hands. The originating (maybe sole?) manufacturer was J.S. Popper company, now apparently owned by Mueller. The clips are widely available from distributors like Digi-Key, although they aren’t cheap.

      http://muellerelectric.com/product-category/alligator-clips-insulators/telcom-popper-clips-insulators-at/

      I have the JP-8783 version, which has a combination of jaw features sufficient to grip just about any part.

      1. Those are really neat. They would totally be worth it if you were up to something nefarious and needed to do some sort of wiretapping. The insulation-piercing jaw hardware is really interesting.

        If I was on a bomb squad I’d want a set of jumper wires (using some solid silver stranded wire to try to keep resistances as low as possible for the jumper itself) with these clips on the ends. :)

  8. I got a pack form Radio Shack 40 years ago and they have been wonderful. No broken wires, they will grip small things because the teeth actually line up as they should and the insulated coating is long enough and thin enough for it to do what it should.

    I have not been able to buy similar despite lots of trying I always end up with ones that you need a G-clamp to open because the insulation on the clip is so thick and it is always too short.

    1. I bought some rat shack test leads with micro alligator clips many years ago (but not 40!) and they were all SOLDERED. Worked great, lost them in a move along with all kinds of other electronics hobby stuff. They were almost certainly made in China, but before their current “well this kinda’ LOOKS like what it’s supposed to be, so it’s good enough” phase where they all have the horrible crimps pictured in the column above.

    1. We must be forgiven as we do not have such beasts here to inspire inventions. But regardless of my “entire country getting it worng” croc clip rolls of the tounge a bit better. A technical bulletin will be posted, but i fear my country is too far gone to remedy such a important mistake. But thanks for the Mueller info, they know thier stuff it seems

      1. I find it hard to even SAY “croc clip” – it comes out as “croc lip” or “craw clip”. “Gator clip” is much easier. But I’m really stretching the picking of the nits here – thank you for your comment.

  9. If you must use alligator clips, use good quality branded clips from the likes of Mueller, Hirschmann, Fluke, Cal Test/B&K Precision, Pomona or E-Z-Hook. Unbranded alligator clips are wobbly, have dubious electrical properties and are prone to corrosion. Make up your own test leads using silicone-insulated cable – the extra flexibility and heat resistance is a huge advantage compared to PVC.

    For most purposes, you’re better off with hooks and grabbers. They grip much more securely to component legs and they take up much less space around the board. The smaller conductive area at the tip means they’re far less likely to accidentally short against adjacent components or traces. Again, buy from a reputable brand – unless you’re really short for cash, the cost savings of cheap Chinese test clips aren’t worth the frustration.

    Thoughtful board design can save you a lot of grief when it comes to debugging. Plan for testing throughout the board layout process. Wherever you think you might need to probe, add a footprint for a pin header or a suitable RF connector. If the design goes into production, these can easily be converted to test points for in-circuit testing. A few mm^2 of board area is usually a price well worth paying for easier testing.

  10. I’ve never had a chance to form a love/hate relationship with any specific test lead, because the darn things never stay put. They start life hanging neatly on a nail by my bench, then they enter service on a project for one week to several years, then they simply evaporate and I have to buy another bunch. Some occasionally pop back from the parallel universe to show up in the bottom of my tool bag, but they are soon gone again.

    I’ve bought cheap ones and resoldered them, and i have bought some better clips and made my own. But they all get up and leave eventually.

    Alot of modern gear is simply too tiny for alligator clips now. I have several of those tiny lead-grabbers, or I’ll just temporarily tack-solder a wire or a cut resistor lead to a point I need to use repeatedly.

  11. I bought a few sets of crocodile clips and while some are fine (Conrad), some are extremely shitty (random ebay stuff).
    I was testing a 6v car radio. Didn’t work. Thought my battery was dead when i measured the voltage in the radio. Noticed clip leads were getting really warm. Too much resistance.
    Why? Because they are made from steel and not from copper. The wire itself gets attracted by magnets.
    I also had a lot of the intermittent problems, including with clips from the local electronics store.
    Solution: radically replacing all clip lead wire with some 0,75mm^2 flexible wire.

  12. After much pain and suffering from purchased clip leads I have vowed never to use commercial ones again. So now just buy clips and build my own.

    The biggest I found was the as others have mentioned the the few strands – no hair is thicker!
    Folded back and “crimped” in with the insulation was number one problem. And these aren’t eBay specials but “heavy” duty ones from a popular electronics store In Australia – YesJaycar I’m talikning about you.

    There is one advantage though. They act like a slow blow fuse with early warning – the insulation starts melting just before the wire breaks

    1. Your mistake is in thinking that anything in Jaycar is not just eBay special with a Jaycar price. Not that there is anything wrong with that, sometimes convenience is worth it, but don’t go thinking you are paying for better quality.

  13. Yeah that crimp of insulation AND stripped end is the world’s worst cheap trick. Perhaps there caiman clips in Brazil! Alley-gator it is, croc clips are the heaver built crossing jaw type usually good for more current because they have stronger springs inside hence the bigger area to squeeze to open them up.

    For most of my life I have used a alligator clip melted into the end of a red plastic probe which has a hard steel wire ground into a sharp point soldered at the rear end sticking out of it’s mouth about 1cm. A heavier clip is on the minus lead, since most of what is measured is to ground. The probe is used like such with it’s dangerously sharp tip, but in an instant it can be clipped to anything but a nearly flush terminal for hands free monitoring.

    Those blunt tip two-handed test probes and separate leads are always tossed aside for every multimeter I have. I save the pen sized red and black prods though. A black prod handle with hard steel tip and 12ga wire running up through it to a loop to clip the minus lead onto serves to do base-emitter tests etc. The wire is just flexible lamp cord left zipped together for the greater length of the test lead(s). I hate having two separate wires running all the way to the meter, like having headphones where one wire comes to the left side only for both channels.

  14. I make up leads using silicone insulated wire 18AWG and 2mm RC banana/bullet plugs, then put Hirshmann MA1 2mm crocodile clips on them as required, or 2mm to 4mm banana adapters, or plug them into other things I’ve put 2mm sockets on. Typically I’m driving less than an amp through them for small motors or power LEDs.

  15. i like “ic test clips”, or “mini hook clips” or what have you. i take them apart when i get them, and hot melt glue the wire to the plastic so the solder join doesn’t fall apart right away. they don’t handle current *at all*, i’ve had them explosively disassemble from a transformer’s inrush current.

  16. On a related note, where do people buy silicone wire from?

    I’ve been using Adafruit for the thin 30AWG and 26AWG wire, and HobbyKing for the heavier gauges. About 20AWG seems right for general purpose test leads that can handle a little current.

    Any better/cheaper vendors out there? Being able to get the full decade of different colours (like resistor colour code) would be really nice.

  17. The cheap ones are also mechanically crap. The jaws don’t “bite” symmetrically. I usually try to get the best quality ones I can find use 18-22AWG wire with 600V insulation and high quality boots, not the cheap PVC on most of the China crap.

  18. I don’t think I’ve ever heard anyone outside of HAD calling them “crocodile clips”. I had to look it up to see if there was some minute difference between a “croc clip” and what I was seeing that looked an awful lot like an “alligator clip”. I’ve always heard them called “alligator clips” anywhere else, although that seems to have been hotly debated on the Wikipedia Talk page for that article as being a regionalism.

  19. The first time I noticed there was after I bought them from an otherwise reputable parts dealer.

    I used one between the earth strap of a CRT and a screwdriver to discharge the TV tube Anode.

    There was a ‘twack’ upon which the room inverted as the floor swung up and smacked me in the face.

    After that every alligator clip lead was inspected and soldered and a short piece of heat shrink was placed over the middle of the wire to indicate it had passed a safety inspection.

    No days just about every thing that comes from China uses the metal strain relief tab as a crimp connection – can be very dangerous.

    PS: We call them alligator clips here, not crocodile clips.

    1. ahhh… the perpetual confusion has now reached the lab.
      Below the difference and you’ll see that alligator is the proper name (or not…)

      PS: although I’m a user of these devices myself, I never understood why some people make all connections with these clips. Looking at the photo of this article I wondered: “You’ve soldered a complete PCB, but some properly connected wires are a problem? Just solder the wires to you board and there are no problems”. These clips are intended to clip onto things that you cannot (or want to) solder to. Only use them when really required, don’t use them for everything, then you only need a few and there is no real excuses to buy some good (not crappy) ones.

      1. Awesome illustration. I’ll never make the same mistake again, whether being chased by a large, bloodthirsty reptile or cursing at snaggletoothed intermittent clips!

        Seriously, I have no idea why I wrote crocodile over alligator. I wonder if it’s regional? Some people in the South use “coke” as the generic for soda — what a midwesterner would call “pop”.

        As for the board, it’s a white-noise generator test board. I tend to put it into all sorts of circuits. I actually etched the signals around the edges to make them easier to clip on to. Not sure it was a good idea, and it’s much easier to clip on to wire loops. But it was an idea.

  20. — constantly fall off
    — too large; creating short circuits (not just SMD, but 2.54mm DIP as well)
    — either too long, too short or not flexible enough
    — you’ll always need one more than you have at hand
    — either shitty quality or relatively expensive

    just solder on small wires, way neater, sturdier, and cheaper

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