Cheap Alligator Clips for your Multi-Meter
A friend of mine a while back bought me a multi-meter (thanks T-Bone!). It’s a pretty darn good one too, but just like everyone else who uses a multimeter often, I found myself wanting a way to attach my leads to wires and have them STAY there. Before I knew about places like SparkFun and Parts-Express, my shopping experiences told me that new leads were going to be too expensive for as often as I use them. So it went that I just continued to pretend I was ambidextrous, or held the probes in my mouth (what? eww…) or otherwise just failed. Until one day I had enough. I just had to have some alligator clipped probes. On a recent trip to Harbor Freight I had purchased a 6 pack of alligator clips for about a dollar for another project, and had four left over. In my desperation I actually had wire cutters in hand with the jaws on my test lead about to cut… … …but I couldn’t do it. I just couldn’t sacrifice my leads, even in my desperation. So I sighed and tossed my pliers to the side and sulked.
Now sulking is when I do my best thinking. You see, it is then that I throw all calculated and rational thought out the window and begin to fantasize about wild possibilities and ideas that usually involve too much money. “Wouldn’t it be nice, ” I thought, “to just be able to have interchangeable probes on my test leads? Not have to change the whole lead, but simply put on a new attachment, like with a vacuum cleaner?” Then I had an epiphany. I could crimp down the ends of the alligator clips enough to slide them on the probe tips! Yeah!
No. After completely mutilating two alligator clips, I came to the realization that they were too big in the barrel, too cheap of metal to retain any kind of tension, and would not last. There had to be another solution. But what? I shelved the idea until another day…
Then, on another project, ‘Making a Bench Power Supply out of a PC Power Supply’, I stumbled on my idea. I was testing the output of the power supply, and again didn’t feel like holding my lead, so I jammed it into the pin on the Molex connector- and it stayed! And it didn’t just stay, it stuck! So the Power Supply project got way-laid by the resurrection of this Alligator Clip project.
Here is what I did:
Find a ‘something’ with a male molex connector on it. In this example it will be a cooling fan off a Pentium-II, maybe- I don’t know where I get this stuff.
But the part I am interested in is the Male Molex connector. It has the nice open pins as such:
In order to take the Molex connector apart, you will need a Molex pin removal tool. Well, you don’t have to have one, but it really helps. You can just use a needle, or jewelers screwdriver or something. The tool looks like this:
The tool has two different sized ends, one for the female pins in the male connector, and one for the male pins in the female connectors. I guess Molex connectors are bi-sexual? Yeah. So the end we need for the male connector/female pins is the larger end.
These tools are designed to slide over the pins and disengage the little retaining flanges that flare out and hold the pins in place.
And, uh, here is the tool being used…because, uh, yeah.
Once you have a pin out, it looks like this.
Yay. Now what do we do with it? Well, I cut it off at about 2 inches, then I tinned the end of it to make it nice and solid and a little bit malleable so it would fit better on the screw. I bent the tinned wire with some needle nose pliers into a hook, and torqued down the screw. I made sure I ran the wire through the opening, and not just on the outside of the clip. These screws could be tightened down a good bit, and hold VERY well.
Once the whole caboodle is assembled, you have to make it tight. Molex connectors are made with a little bit of a gap where the two ends meet (see pic above). Take your fingers, or a pair of pliers if you will, and squeeze the pin so that the ends of the metal touch. This makes the connection tighter. I also pinched the little flanges inward into the barrel of the pin, such that they ‘locked’ into the little depression on my probe.
Attaching the alligator clip to the probe is as simple as sliding it on. The little flanges help lock the probe in place, and the wire is stiff enough that they don’t flop around aimlessly. Removal of the alligator clip is just as simple as pulling it off since the flanges lock onto the probe, but don’t “LOCK” onto the probe. Hope that makes sense?
The clips on the probes hold exceptionally well. How well? There have been a few times my multimeter has fallen off the bench, and the probes did not release and took the project with them on the plummet to the floor. Here is an example of the retaining strength of these:
There is a pic of the probes and clips holding up my multimeter. For that pic, I just held it up in front of my chair. I wasn’t even ginger with it. I was going to shoot a video of me bouncing the whole thing a little, but they couldn’t hold up to that, just to give you an idea of the release point. The clips in question in this picture are more than 4 years old, and are in fact the first set I made. They still hold today as well as they did when I made them, and I have not rebent the flanges in for a better hold, even for this picture!
All in all this has been one of the simplest and most beneficial tool mods I have ever done. I guess you could say I got the most ‘mileage’ out of these. When on the multimeter, they have no resistance and make very good connections. I also just found out recently that they fit perfectly over 12 gauge solid wire. The little flanges, again, help ‘bite’ into the soft copper. This is wonderful for making impromptu and temporary jumpers and whatnot. Another small added little benefit is that with the Molex connectors you get the most common wire colors to choose from: Red, Yellow & Black. This way you always can tell your + and – sides!