[0:00] [bubbling sounds]
[0:04] So I saw one of these resistor boxes on the EEVBlog channel and it’s pretty good.
[0:09] It works quite well.
[0:10] So we can do 10k increments.
[0:13] [clicking sounds]
[0:15] We can do 1k increments.
[0:17] [clicking sounds]
[0:20] 100.
[0:21] [clicking sounds]
[0:22] And we can go down to 10.
[0:24] I’ll have to switch my range.
[0:26] 10 ohms, 20, 30, all the way down to 0.1 ohms which my meter, as you can tell, it’s measuring
[0:35] 2 ohms already.
[0:37] It doesn’t really have the accuracy for 0.1 ohms.
[0:41] It’s quite an interesting construction.
[0:43] It’s definitely made to a price point so these binding posts are particularly cheap.
[0:52] So one very simple upgrade would be to replace these with some nice fancy binding posts that
[0:59] have the nice push wire connectors.
[1:03] Let’s take a look at the actual construction and see what we can do with this.
[1:08] I’ve taken it apart once already and you can hear the rattling of the screws inside and
[1:14] my dirty fingerprints because there’s a bit of grease on the buttons.
[1:18] But if we pop this open you can see the quite interesting construction.
[1:24] So one of the interesting things is that they’ve got away with just using five resistors on
[1:29] each of these sweeps.
[1:30] So if we look at, say, the 100 ohms, it’s currently on 0.
[1:36] So you can see it’s currently connecting directly from the input to the output of this ring.
[1:42] And as we switch it around, so 1 includes 1 resistor and then 2 resistors, 3 resistors
[1:50] and then 4 resistors and then it switches over to a 500 ohm resistor.
[1:57] So there’s an interesting arrangement here where the voltage comes in through the 500,
[2:02] goes through this ring and then to the output and now from now on as we swing around we
[2:08] have 500, goes across here and we have an extra 100 giving us 600 ohms, 700, 800, 900
[2:17] and then back to 0 again.
[2:19] So that’s pretty clever but one thing you can see, I think it’s clear, this is just
[2:24] plain copper.
[2:25] So as we turn this around and rotate it, it slowly scratches into the copper.
[2:32] Now someone pointed out on the EEVBlog channel that nickel plating at home is actually quite
[2:38] straight forward.
[2:39] So I thought, fantastic, why not buy one of these and then we can try some nickel plating
[2:44] and see if it improves the durability of the copper.
[2:49] So the only other interesting thing is the actual construction of these buttons.
[2:53] So it’s got a nice clicking thing here, that’s probably really annoying in the audio, I hope
[3:00] I’m not deafening people by clicking right in their ear.
[3:04] But if we unscrew this, it’s actually an amazingly simple mechanism.
[3:09] So that should unscrew that and now this knob should come off and what you can see is there’s
[3:18] just a small ball bearing on a spring, now I think that’s visible and on the underside
[3:25] of the switches there’s just little divots where that ball bearing slots into.
[3:31] So when you have this pushed down, it clicks around quite nicely.
[3:36] So that’s a really neat, clever construction, obviously quite cheap as well.
[3:41] And here’s the horrible grease that I got all over my fingers when I first took this
[3:45] apart.
[3:46] So what I’m going to do, I’ll take that out now, I’m going to remove this PCB and I’m
[3:54] going to try nickel plating it and then we’ll see what happens.
[3:57] So I’ve removed the PCB and I’m sure you’ve all been shouting at the screen going “you
[4:03] idiot!”
[4:04] It’s never going to work, you want to use electroplating to get nickel onto this but
[4:08] you’ve got all these resistors and I think you might be right, that is going to be an
[4:12] issue.
[4:13] One eternity later.
[4:15] Well that’s an hour of my life, I’m not getting back but I’ve soldered jumpers over every
[4:21] single resistor so now everything should be connected.
[4:34] So that’s pretty good, we should get current going to everywhere.
[4:37] So this should plate nicely I think.
[4:39] So I’m now going to try and create some nickel plating solution.
[4:43] So I have this nickel strip, it’s not ideal because it’s quite thin, I think ideally you
[4:49] should have something quite thick for your electrodes but I put a negative electrode
[4:53] around the edge of this bowl and I’ve got a positive electrode going in the middle and
[4:58] this is all sitting in a bath of white vinegar that’s five percent strong.
[5:03] Now I’ve got my power supply here so I can control the voltage and the current.
[5:08] Now there’s just a couple of things, reading it on the internet we should add a bit of
[5:14] salt to our solution to make it a bit more conductive so I’ll sprinkle a bit of salt
[5:19] in, that should do it and apparently you can add some sugar as well so apparently that
[5:29] acts as some kind of brightening agent which should make our plating work better.
[5:35] Now I’ve seen a few people saying it doesn’t really work or you need to actually do some
[5:40] experiments but I was thinking a bit of salt in as well.
[5:44] So let’s just stir this around, try and get it to dissolve and that’s probably good enough
[5:50] for now.
[5:52] So what should happen is our liquid should turn a nice shade of greenish blue so let’s
[5:59] turn on our power supply and then we’ll turn the constant current up, now I may have to
[6:09] increase the voltage to actually get any current flowing so let’s turn our voltage up.
[6:16] I’ve seen various things on the internet about how much voltage to use, some people say very
[6:22] low, some people say very high for this initial stage, now let’s actually try and get some
[6:28] current flowing, so I’ve got 0.1 amps, 0.2 so I think we’ll leave this about 20 volts
[6:43] and let’s just limit the current so I will, it seems to be current limiting at about 0.4
[6:52] amps so let’s just bump that up a bit so I’m going to current limit at about 0.5 amps.
[7:00] So we’ll leave this running for a while, we can see some bubbles forming so we are doing
[7:06] some kind of electrolysis, hopefully our liquid will change colour so I will check back on
[7:13] this in an hour or so and see what’s happened.
[7:17] And there we have it, a beautiful emerald green, so what’s gone wrong, apparently this
[7:24] nickel strip is actually nickel plated steel so that’s not going to work, what I’ve produced
[7:31] is some interesting slightly brown liquid.
[7:36] Okay we’re ready to give it another go, I now have some proper nickel, now I’m not sure
[7:42] why I was testing with a magnet before because obviously nickel is magnetic but let’s unwrap
[7:49] these, I’ve bent these into this shape so I can put them into my bowl and connect the
[7:55] crocodile clips to these parts so let’s get the show on the road.
[8:03] So there we have our nickel electrodes and I have here my little power supply, connect
[8:11] this to the positive, connect this to the negative and now I need my vinegar and once
[8:24] again we’ll add some salt, just a little bit of salt, give it a little stir to help it
[8:31] dissolve and we’ll add a bit of sugar, let me stir that as well.
[8:40] Okay so that’s about there, now I’ll just plug in the power supply, okay so let’s turn
[8:53] this on and see what happens.
[8:59] Okay so our output is 66 volts and our current is currently pretty low, so let’s leave that
[9:09] at quite a low voltage, I think a low voltage should be better for this kind of experiment,
[9:15] I’ll leave that running for a while and we’ll see what happens.
[9:19] I can see some bubbles forming so something is definitely happening, so hopefully we should
[9:25] get a nice green liquid this time, let’s see what happens.
[9:37] So that’s worked pretty well, I ended up turning up the voltage to get more current going through
[9:43] the solution and I’ve messed around with the position of the electrodes, but we’ve got
[9:50] a fairly decent nice solution, it looks quite pale from above but if I just move the camera
[9:55] down to the side you can see we’ve actually got quite a nice colour, so I’m going to decant
[10:00] this into a jar and save it for later, so that’s pretty good.
[10:05] So there’s a couple of interesting things, here’s my nice nickel plating solution, it’s
[10:12] a pretty nice colour, very very nice, so I think that’s going to work well for our experiments.
[10:18] If you look in the bottom of the dish I was using you can see a few specks of some material,
[10:28] so I guess our nickel electrodes aren’t quite as pure as 100% nickel, it’s interesting to
[10:35] look at the positive electrode and you can see that it’s been dissolving away into our
[10:41] solution, so the corner there has gone quite rounded, it used to be a very sharp corner
[10:47] like this, so this is the side that was closest to the negative electrode, so that’s been
[10:52] dissolved away and on our negative electrode you can see that it’s been building up a coating
[11:01] of nickel, so that’s also very interesting, so although we’ve got nickel in our solution
[11:08] we have also been adding to our negative electrode, so this is also very interesting, I can basically
[11:15] scrape off the nickel plating from the negative electrode, it produces all these little bits
[11:22] of nickel which are all magnetic as well, so that’s quite cool, collected all these
[11:31] little fragments of nickel, pretty interesting, well hopefully our nickel plating will work
[11:38] slightly better than this when we try it on the PCB.
[11:42] So I thought we’d start with a fairly simple test, so I have here a little coin and I’ve
[11:50] got my power supply running on quite a low voltage, so I’m just trying it on around 2
[11:58] volts, so let’s drop this in and see what happens, now I can see some bubbles coming
[12:06] off, which is a good sign, and what I’ve done is I’ve connected both of these nickel electrodes
[12:16] to the positive supply, so I think this is actually working, it’s quite slow but it’s
[12:22] definitely changing colour, I think that’s definitely worked, I might leave this in for
[12:29] a few more minutes, but our nickel plating solution is working nicely, I think that’s
[12:36] pretty good, very cool, it seems to have worked, nice, I think we’re ready to nickel plate
[12:54] our PCB, so let’s give this a go, what’s the worst that could happen, so I should be able
[13:03] to fit this in, I think if we go this way round we won’t short anything out, so this
[13:19] is very interesting, I can see bubbles all the way to here, but I wonder if my jumper
[13:25] wire here is not quite making contact because I don’t see any bubbles after that part, so
[13:33] what I might do is take this out and just double check that connection there and make
[13:38] sure it is wired up, ok, we’re ready to go again, let’s turn the power on, now I can
[13:47] see on my power supply is about 0.1 amps going through, and I’ve got it set to around 2 volts,
[13:55] so hopefully we should start seeing some bubbles soon.
[14:11] Well it’s an interesting result, but it’s not quite the result I was hoping for, it
[14:16] has kind of worked, so we do have some nickel plating on our copper tracks, but it’s not
[14:22] worked everywhere, so for some reason we didn’t get any nickel plating here, there’s a few
[14:27] places where if you look closely you can see the bubbles were too much, not sure why this
[14:33] area is black, but it’s not quite worked has it, more experimentation is required.
[14:39] Now you may be thinking, what a shame, the resistor box is completely broken, well not
[14:45] so fast, the guys at PCBWay have produced these PCBs for me, so I have recreated the
[14:52] exact circuit from the resistor box and got it made up, so I’m going to solder one of
[14:59] these boards up and we’ll rebuild our resistor box, so one thing that is quite interesting
[15:05] is why it’s not worked so well, if we look at this coin it seems like it should have
[15:09] worked quite well, so I am wondering if doing it in that shallow dish just wasn’t a good
[15:14] idea, I wonder if maybe having the PCB vertical in a big jar of the solution might have worked
[15:22] better, so I will definitely carry on some experiments, but in the meantime, let’s get
[15:27] these new PCBs wired up and rebuild the box.
[15:40] So I’ve attached the original flying leads, now I just need to attach these to the mounting posts.
[16:09] Let’s put the springs back in, and then we’ll put all of these back in the zero position,
[16:16] then we flip over, and of course everything drops out, it’s like, ah, very annoying, maybe
[16:25] we should do this one at a time.
[16:28] So the important thing in the zero position is that we have zero ohms, which means we
[16:34] need to put these things this way round, so we come in here, we go around, go straight
[16:41] across and we come out here with no resistors, and there we have it.
[16:46] So that will be zero, and then we have one, we have the one resistor, two, three, four,
[16:55] and then five, six, seven, eight, nine, back to zero again.
[17:01] So I’ll quickly do the rest of these, and then we’re back together, so there we go,
[17:05] back together.
[17:06] Now, you can already see, this is a hassel coated copper, we’re already marking this,
[17:13] so we’ll see how long this actually lasts, but I do have quite a few of these PCBs made
[17:19] up, so no shortage of replacement parts, but let’s see how this works, I will carry on
[17:27] investigating the nickel plating, see where I can get rid of that, and see if that makes
[17:32] any difference at all, but there we go, we now have quite a nice resistor box, we’ve
[17:37] got some nice binding posts here, I’m quite pleased with that, I think that’s made a bit
[17:45] of adjustment on this one, there’s the hole, so we can put banana plugs through there,
[17:52] maybe I’ll spin these around to make them slightly more accessible, but not bad.
[18:00] My new resistor box is finished, I’m not sure what I’ll do with this, it’s probably destined
[18:07] for the bin I think, pretty much ruined, although an interesting experiment.
[18:14] The nickel coating does actually seem to be fairly robust, so it’s quite hard to actually
[18:21] scratch it off, he says, and then manages to scratch it off quite easily, but definitely
[18:30] a fun experiment, I shall do more of this, and see where we get to, yeah, fascinating.
[18:38] So I thought I’d give it a go with one of my PCBs, now I’m not sure how well this will
[18:43] work, but I’ve sorted all of these jumpers on the back so everything is connected, and
[18:50] I’ve given it a good clean using isopropyl alcohol, so let’s drop this in to the bath,
[18:58] and push it down to the bottom, and then we’ll hook this up to the negative electrode, unfortunately
[19:07] I’ve used red wires, I should have used black, but that’s fine, doesn’t really matter.
[19:14] So I’ve got wires connected to both ends of the PCB, so that’s hooked up to our negative
[19:20] electrode.
[19:21] I’m going to take my gloves off because they’re a bit wet now, and let’s turn on the power.
[19:34] So that was definitely interesting, so here’s the PCB that was in the solution, I left it
[19:41] in for quite a long time, and I brushed off any bubbles that were forming, and you can
[19:46] see that it has changed colour quite a lot, so if we compare it to the previous board,
[19:52] this one’s very shiny with the hassle of coating, this one you can see we have a slightly more
[19:59] dull coating.
[20:02] I do think there may be some contamination in my solution, so I’m going to have to run
[20:07] this all again, but I’ve got a much more sophisticated setup for that.
[20:12] So let’s just do a fairly non-scientific test of the coating, so I’ll just try scratching
[20:18] it.
[20:25] So it’s not that hard, I’m not sure if that’s really visible in the video, I’ve made some
[20:32] small scratches, but let’s compare that to the original boards, I’ll try and use the
[20:36] same amount of force, well that is interesting, those scratches are much more visible than
[20:47] the scratches I just made on the coated board, so you can definitely see the scratches here
[20:54] compared to my coated version, where the scratches aren’t actually very visible at all.
[21:04] So I wonder if my coating is actually working, or maybe it’s just this surface is not quite
[21:10] as reflective as this one.
[21:14] Very interesting, so I will definitely do some more experiments, but this video is now
[21:20] incredibly long, so I will stop here.