Hi, it's product review time. Been excited about this one. Been wanting to get one of these little puppies for quite some time and uh, thanks to Dan Evans at Sag.com he gave me one of these so thank you very much. Dan Fantastic! Um I Had to wait quite some time to get one because apparently they're in high demand.

so go figure. We'll talk about that. What is it? It's the Aim: TTI Positional Current Probe: It's pretty much a Uh world first in Um test instrumentation. It's well, it's a current probe, right? It measures current but allows you to do it um, by just probing over the PCB track.

you don't have to actually break into it with a loop of wire and and put your little clamp around it. and things like that. You've been able to buy uh current probes for oscilloscopes for well as long as I've been alive anyway. So um, but they've all had that one limitation of having a little magnetic clamp you got got to put over put the wire through the clamp in there in order to measure the current.

But these ones you don't you just probe the PCB track. You get the waveform on your scope. Brilliant. Does it work well? Let's find out.

Why haven't they done this before? Why haven't these been on the market These current probes. It's because it uses a new patented Uh technology from I Believe Uh, Cambridge University Uh in the UK And they're the ones who developed the flux magnetometer in in this thing which allows Um this positional current probing technology and I believe the reason these things have been hard to get is because the fluxgate magnetometer used in here here the special patented sensor um is still made by Cambridge or some arm or division or something of Cambridge University I could be corrected on that, but apparently um yeah, the supply is limited by how many of these little sensors patented sensors they can manufacture. Had no luck in finding the Uh patent number or the patent. So if you can please uh Post in the comments or on the Uh forum and we'll take a look at it.

But what is a Fluxgate magnetometer? It's a very simple and very old technology. It dates Back to Before the War I believe and War that's not the war on Terrorism kitties, that's WWII Okay, so really old technology and it's traditionally used in things like electronic compasses back in the day before they were placed by more modern technology. I've worked on a military Uh Sonor Boy design which had a flux gate magnetometer in it and there's very various ways to physically construct them, but they all work on the same basic principle so let's take a look at it. It's really easy and basically what it reliz on is a Uh magnetic Uh Coe like this with a drive winding wound around it like that and it's going to be a low saturation material so that the magnetic field generated by the drive signal can saturate this core.

Really easy because the core must saturate. That's a key part of it. And pretty much, um, what you want to when you design a flux gape magnetometer. They're designed to detect magnetic fields.

That's how they work. So this Black Arrow here this um, up direction will take that as the reference direction of the magnetic field that we want to measure. Okay, so it's just a simple coiler wire around a low saturation core like this. and it basically they the drive signal just goes positive negative: It'll be a square wave like this.

so it drives the core into saturation and you can effectively split it down the middle into two halves like this. so they'll be flowing through that way and there'll be one flowing down like that. So you put it into two halves and it basically saturates it one way and then the other. and based on your drive signal.

so you'll get a saturation waveform which looks like this for One Direction. And if we have our black so so that'll be our blue side here and our black side here will saturate in the opposite direction like that. Simple, and what use is that? Well, we can use this and another a secondary sense winding to detect changes, minute changes in the M an external magnetic field. So what you can do once you've got a core like this being driven, you can actually put a sense winding all the way around the outside of it like that.

There's many different ways you can physically construct these things for the maximum sensitivity. and there's multicore types and all sorts of things, But this is basically how it's done. We're going to put an external field around external sense coil around that, and this will generate a voltage on it based on the flux induced from this dry voltage down here. But as you can see, they compliment waveform.

So if this thing is sitting in the middle of space, outter space, and it's got, there's no external magnetic field at all. It's well away from the sun, it's in the interstellar medium or whatever. There's no magnetic field, no external magnetic fields around here, then this alternating waveform will precisely, or if you construct it right, should precise l cancel it out and you'll get no voltage induced in this sense winding. But as soon as an external magnetic field, as soon as this whole coil system this whole flux gate magnetometer system is, um, in the presence of an external magnetic field, it will actually adjust the bias point, the saturation Point slightly of one half or the other, and you will get a waveform out of of this.

You'll get a voltage out, and if it's high, you know it's high. It's constructed properly, it'll be high bandwidth, and you'll actually get a signal out of this thing that you can hook up to your oscilloscope. And that's basically all there is to a flux gate magnetometer. They're actually quite simple, but very quite tricky to actually manufacture and perfect.

And get them precise and absolutely precise. And get them and get a high bandwidth like we have in the Um Aim TTI Ey prober. So why hasn't somebody developed one of these before with a flux gate magnetometer sensor head? and you can put it uh and put it right against the track? Well, if you got your PCB it's got to be small enough to actually and close enough to be right within the magnetic field because the magnetic field surrounding a a trace on a PCB will roughly drop with a square of the distance. So it's not like you can have some big coil up here.

you know, an inch away from the board or something like that. It's not going to work. It's got to be right on there. So the real Innovation here is not that they're using a flux gate magnetometer to measure a magnetic field on a PCB Trace.

You've technically been able to do that for, you know, forever. Um, it's to make it small enough and Tiny enough to fit right at the tip. there. That sensor head, that tiny little sensor head.

It's going to have a little to or something like that and it's going to have the coils in there probably I Don't know if it's just a single Uh drive and a single sense winding. It could be multiple ones I'm not sure, but it's got to be small enough to fit into there and that is the patent. and that's the Innovation which has enabled this thing because you've been able to. You could use other Technologies like uh, hall effect, uh, sensors to do uh, something like this in theory, but in practice um, their, you know their bandwidth is going to be core and all sorts of other issues.

So a Flax Scape magnetometer is the ideal thing to uh, measure current through a PCB Trace without having to break it. It comes in a nice uh, zip bag like this because it's not a really an often used instrument. so really you want to and it's a bit fragile. so you uh with you know wires and leads and things so you want to really, um, probably keep it in a case.

so it's a really nice idea for them to supply it in a case like this. It's got a nice foam uh, padded insert you could put cutouts in here for other stuff if you wanted to and a certificate of Conformity and we've got ourselves which we'll see later. a um, a laminate a nicely uh, laminated reference chart which you're going to need to get an absolute value out of this thing because as you'll see um, these are great for seen waveform But For actually measuring it, it's going to be a bit tricky and you get the instruction manual which is all no which is in different languages and it tells you about the Practical aspects of quantitative measurements. all that fun stuff, measurement in PCB, traces, etc etc.

Looks like it's good enough. The Uh probe itself of course and uh, it's You know it's got a cable which is about a meter long or thereabouts which goes to the main unit over here which is the Uh calibration box as it's got a calibrator uh, build in. It's got various modes which we'll take a look at and bandwidth and some knobby adjustments here. and uh, that has a thin BNC output which goes into your oscilloscope.

There's a Uh, there's a plug pack here with multiple um, different, uh, you know, Mains adapters for around the world. and we also get ourselves a Um one of these, uh, traditional, more traditional current clamps where you can just put it on the end and at bingo. instead of having the positional thing, it turns it into your traditional Um current. you know, oscilloscope current probe system where you put the wire through and that will be a lot less sensitive to the position of the probe.

So if you want some, you know, some real easy uh, absolute measurements. Um, and you have a wire available to put through, you're much better off using this Um core. If it's 300 volt cat to rated, it's got some really nice finger guards here I Really like these. So because one of the Uh uses one of the primary uses of this is uh, probing the Uh traces in high voltage.

uh, high energy High current switch mode power supplies so you don't have to break into the trace, you know you can get through all the circuitry and probing there and it's a good distance back so your fingers aren't going to touch live heat sinks and things like that. and really, it's going to be hard for your fingers to slip past those probe guard. So I really like that and it does, uh, feel really rugged. Um, it's you know I've got no problems with it at all.

It's got got good strain relief on the end here and uh, the probe itself. um, because it's going to be touching things all the time. hopefully. um, it should wear fairly well, but it feels really like a solid bit of Kit The first try time I tried to put this on I was you know I thought I'd break it or something like that, but you got to just use a little bit of force and it just locks in place like that and there's a little bit of play in there.

but uh I don't think that really affects the accuracy much at all. That sort of locks on there really nice and you just give it a bit of a Twist and it comes off I Like it. Good design and the electronics. uh box here which contains the Uh I I presume the driver or the uh, you know, the amplifiers and uh, things like that or the driver might actually be in the head itself.

I'm not sure. Um, by the way, the Um Mike at Mike's electric stuff has done a tear down uh, the probe and the box as well. so I'm not going to do one, he's already done a good job with that. So I'll link that in here.

so if you want to see what's inside these, uh, please check out Mike's video. He's done a good job because it's a bit destructive. You know there's lots of Mag There's lots of shielded cans inside this thing and uh, stuff like that. So I don't really want to go.

um, you know, desoldering hacking Min apart when Mike's already done it. Anyway, the uh control box here is it feels quite rugged, good quality, uh, stics, and uh, it's got a Um 5V 5.2v DC input comes from the plug pack to power the thing. Why? it's 5.2 Vols instead of 5 Vols I Have no idea. It's got a calibrator output here which allows you to put the prob down in there and we'll try that out later.

It's got ACDC mode and you can switch it off because if you're doing absolute measurements, very important to calibrate this thing and that's why we have that chart. um in the box. Now it's got three band got a very low frequency practically DC down here. Uh 2 HZ measurement.

If you're measuring very low frequency or DC magnetic field, you might want to put on the 2 HZ bandwidth filter. If you're measuring, you know, low, lowish, uh frequency switch mode power supplies or systems for example, working at 10 khz, then you know a 500 khz bandwidth might do it. Or it's got the full 5 MHz bandwidth, which was quite remarkable for one of these positional current probes. Now now, the frequency of that drive signal um to drive the flux gate magnetometer in the head is probably going to be about an order of magnitude, or you're going to want it an order of magnitude greater than the Uh bandwidth.

the full 5 MHz bandwidth. So it's probably driving that coil at you know, 40 50 mahz or uh, something like that to get the 5 MHz performance out of this thing. And it's that. you could H say that 5 MHz is prob width is probably one of the limitations of this thing because it's you know, if you're if you've got a 1 mahz uh, switch mode power supply for example that you're trying to probe.

Well, of course it's going to have harmonics which are greater than 5 MHz easily, so it's a little bit limiting there. now. There's three modes here. One is wire where you use the Uh clip like this in that wire mode.

so you put it over there and it's going to be absolutely uh C should be absolutely calibrated in that mode and then you've got PCB Trace mode which is the really neat mode we're interested in where you put it next to the Uh Probe on the printed, the trace on the printed circuit board and then it can measure just magnetic fields in the air like it can ma measure the the Earth's magnetic field or a magnetic field um of a product which is you know which which is generating an external magnetic field and of course it can detect whether or not you're overloading your amplifier and you're going to be clipping. So there you go. That's um, all there is to the box and look at this. Beauty made in England made in the Old Dart you Ripper I Love it.

Well done a TTI and uh fby thar what a weird name that is and it's got four rubber feet on the bottom so it really you know it sits on the bench really well and doesn't slide around too much. Let's give it a go. We'll um, use it in the PCB Trace mode here. So you're going to set the mode switch to the center there.

And then we've got our three controls. The PCB sensitivity control is effec, effectively the calibration pot because this thing will not be calibrated unless you put this knob to the right position and you do a calibration step first and that's what we're going to do. and this is where you now need your calibration Uh chart which comes with the unit and it shows you the characteristic response of this Uh probe system. It's got two different Uh probe responses.

one is 2 amps per volt and the other is 1 amp per volt. and uh, it shows you the trace. uh, the um, the calibrator output voltage that you want to get versus the trace width which you're trying to measure. So uh, the one we're going to measure here first up is 1.6 mm wide Trace So we will take that 1.6 mm wide up here and it looks like we need a value of approximately 2.25 Vols out of our calibrator and you'll notice that it's nonlinear as the trace width gets smaller.

So right up here you know 6 and 1/2 7 mm Big fat Chunky Trace That Trace width is very large compared to the size of the tiny Uh fluxgate magnetometer we've got inside here. but once the size of the the probe in here, the flux gate magnetometer becomes a very, very significant compared to the size of the trace as your Trace gets smaller under about 2 mm there, which is roughly the width of that tip there. then it starts to become nonlinear. so this can't work down to arbitrarily small Uh traces.

So what I'm going to use first up is one of these uh, this big thick outer Trace here which is 1.6 mm wide on this um strip of verab board and that uh should allow us to uh, you know, see if this thing is um, you know how far it's out in absolute values I've got the unit here I've put it into its calibrator I've set it to AC over here and basically um, we've got two controls. you can see our Trace rotation. if I move that, it moves the trace up and down. It effectively doesn't uh matter at the moment cuz all we care about is the peak-to peak value.

In this case, the amplitude not the peak to Peak because you got that little that little overshoot there. So just be careful not to include that overshoot so you'll see that the peak to Peak value is actually higher than the amplitude value which takes the value from the flat part of the wave form. So just make sure you don't include that overshoot there. now.

Um, as I said, we've got a 1.6 mm wide Trace that's what we want to do. so that from that chart um, it said we need a calibration value of 2.25 So we need this amplitude to be 2.25 It's quite touchy and of course if you wiggle and if you move this thing, if you twist it side to side, it's it's going to be all over the shop because there's effectively a calibration Trace in there and depending on the amount of pressure you put on it, you only I only have to move that out of fraction like you know, half a millimeter and that amplitude begins to drop. So it is actually very very very very touchy if you can see that so. But the good thing about that is is so you can only undershoot your calibration value.

You can't overshoot, so you need to just wiggle it around, put pressure on it until it's the absolute Max you can get and we're down to 2.15 there. Can we get it up to 2.25 Yeah, 2.27 There we go. So I'm going to call that as our calibration value Bingo Don't touch this pot anymore. This thing is now calibrated for to give us an absolute value on a 1.6 mm wide PCB Trace Now if we have a look at the Uh basic specs in the manual here, you can see it's DC to 5 Me hurts That's its basic Uh bandwidth.

and one really important one here is the noise um, or the equivalent. in the Uh toid attachment there is Um 6 milliamps RMS for the full bandwidth or 1.5 milliamps RMS at the minimum 2 Herz bandwidth set in. So really, you know the absolute lowest you can measure with this thing is, you know, 5 milliamps or above? Basically only a couple of milliamps. So if you're looking to measure microamps with this thing, forget it.

It's just not going to do it. You're going to be down in the noise. Now, the uh. magnetic uh field measurement.

Um, just in free air. It can do 250 uh micro Teslas per volt output with plusus 3% accuracy. and uh, the maximum field it can measure is plus- 2.5 M Teslas which is equivalent to 2,000 amps per meter and using it as a traditional Uh current probe with the toid attachment. There, we're talking plus - 10 mamps to plus - 10 amps with plus - 5% accuracy.

So it's not a hugely accurate Uh device with a 1 amp, a nominal 1 aamp uh per volt uh output. Now what we're going to try and do here is the current measurement in the PCB track and it doesn't give you any absolute accuracy. Uh, figure here because it's going to be dependent upon your calibration. But because, uh, the best case would be in terms of this uh, toid attachment.

You know you're looking at plus - 5% so you can expect the absolute best when you calibrate this thing thing to be roughly. you know that 5% figure as well I would expect. Um, and as here you go, it can measure from2 mm to 3.5 mm 1 volt per output. And there're those dual um, uh characteristic curves we saw on the supplied graph there.

all right Now what I've got here is I've got my Uh 1.6 mm PCB Trace Here it's the one right down the bottom. Show you a closeup in a minute and I've got it hooked up to a function generator 50 ohm output function generator and um, my Fluke 87 is showing the AC current here and I've got it set to 100.0 milliamps at Uh 1 khz. Uh is the rough frequency here and I'll be able to put different waveforms into this thing and see if we can probe it. Let's give it a go.

If we've got Uh 0.1 amps Uh current then we can expect 0.1 volts output from our probe. and in this case because uh, we're using a fluke 87 uh, true RMS multimeter. that will be the RMS value not the peak to Peak value. So we expect to see 100 mols RMS waveform out of this thing as we probe this 1.6 mm Trace Let's see if we let's see if we get it here Now let's you can either hold it I found.

you can either hold it vertically like that if I move it side to side like that, you can see the trace once again going to get smaller or bigger as I move it across the trace. Now as I mentioned before, you can get away with um, you? you can't Uh, you can only underere with this thing. You can't overread the calibration value so you tweak it around until you get to a point where you're' getting your maximum amplitude there and where the maximum we're able to get there is only. ah, it's barely 90 molts really.

And I I find it doesn't matter too much if I put it vertical or have it down like that, we're only talking There you go, You know, 90 M volts is sort of the absolute best we can do and you'll notice when I rotate it, it will eventually Disappear Completely because it's got to be the correct orientation. The magnetic field has to go through the um uh flux gate magnetometer in a certain direction, so the rotational aspect of this is just as important as the side to side position of the trace like that, which is also just as important as the height. if I lift that just a little bit off, you can see it change dramatically. But anyway, the best.

We're getting almost 92 there, 92 molts. So we're like 10% out and we calibrated this thing and I've rechecked and the calibration is still fine. So on that 1.6 mm Trace are about 10% out. I don't know where the error is, whether or not it's in the unit.

uh, itself. maybe? um, a slight measurement. uh, error on the trace I Just use my calipers there, it's probably not exact, be a little bit off, and the chart as well. All that sort of stuff combines to give us roughly a 10% error there.

so you know it. It's not too bad though. I Mean considering that you can probe aboard a trace with no Uh without actually breaking it, then you know if you can get within a 10% ballpark, it's not too bad. It's not as good as I expected though I Expected to be able to get maybe 5% or so.

Here's a rather interesting uh wave form: I'm picking up the 50 htz switching from the Uh from the Heo here and you can see it if I rotate it like that. look at that almost goes away to zip if I put it in that flat orientation. but I rotate at 90 and moved around the unit, it seems to be a sweet spot and I still had that on PCB Uh track mode but we can of course put that over to Uh field mode and we can actually get an Absolute that as an absolute value from that heo. Transformer And if remember the Uh spec sheet for this thing in the magnetic field measurement mode.

it has a Um output scaling of basically Uh 200 amps per meter per output volt and we're getting about 10 volts uh Peak to Peak there. So we're talking uh, 2,000 amps per meter magnetic field on the side of that hoo Transformer and that's actually about um, half of the maximum usable range of this thing. The spec sheet says it can go up to plusus 2.5 millit Teslas or 2500 micro Teslas Let me change this. I've got that's 10 khz.

Let's jump up to 100 khz. There we go. So let's take it up to 1 MHz and let's have a look at it here. I've got my S Wave We got some average in eight averages on just to clean up the wave for.

let's switch it to square wave. It's not going to be a perfect square wave of course and let's switch it to our triangle wave. There you go and we can take that, uh, take that frequency up of course that's actually 10 mahz now. so it's well beyond its well beyond its rated bandwidth.

and of course, this thing is uh, sensitive to the DC offset as well. That's why we have the Um offset Trace position. if I adjust the DC offset control on my function. Gen I can move this waveform up and down and you can see it clip there so we can adjust for with the Uh Trace position control on the unit, we can adjust for any particular Um DC offset on our current waveform.

Okay, now we'll try it. uh in wire mode. So we switch the mode switch here all the way over to wire position there and we snap on our tooro here and we put our wire through as you would on a traditional carrent probe and as you can see, we're getting pretty much spot on. 100 milliamps uh RMS through this wire so we should be able to read 100 molts RMS There's a bit of noise on that, so um, that's a 1 khz waveform.

so I'm going to just knock the bandwidth back there bit of triggering and there we go. It's cleaned it up a bit. We've got our uh bandwidth filter on now as you can see, the position of the wire in here does matter if if you go up and down, there's basically no difference there pretty much, but as it's clearly should be close to the head there, you can move it around the outer thing, but you're supposed to put it against the head itself in there and once you do that, Bingo will spot on to almost spot on. Practically, spot on to what we're measuring with the fluke, so that's within.

Well, it's easily within a% or so there and uh, it's That's a lot better than the specification. The specification is only plus - 5% so it's doing a lot better on that. Traditional wire measurement works really well and of course the uh sensitivity control has no effect. Now because there is no calibration, it's it doesn't need calibration because the toroid keeps the field in there so it it makes no difference whatsoever.

I Thought it'd be interesting to see how much effect that uh, massive magnetic field from the Heo Transformer has on this current measurement. When it's out here, it's about you know, 8 in away or something like that. We're spot on. We're measuring our 100 milliamps RMS Bring it closer.

Hey, there's our 50 HZ kicking in. Now the specs claim that, um, the adding the toid attachment actually, uh, reduces the effect on external magnetic fields by a factor of uh, five? or thereabouts. But obviously, when you swamp it with a huge field like that, you're going to pick up something. Let's switch it off Boop Fine, Look at that.

Perfect and just a quick uh DC check at a larger current. Here, we're getting uh, just under a fraction under 3 amps. And that's exactly what we're measuring with our Toid here. Spot on.

Pretty much well within the 5% claimed. And can we get that same thing without the Toro with the probe? So we're looking for around about 3 volts. Once again, you probe around until you get it to its maximum value. There we go.

we got 2.87 2.86 Once again, it's reading a little bit low as we got before, but there we go. If we tweak it, we can get reasonably close to our 3 amps. anyway. Now, if you got a battery supply for this thing and you got a multimeter and you're stuck in the middle of the Outback somewhere and the sun's not out and you want to know where North is not a problem, all you got to do is turn this thing around until you find the zero and where which is around about round about there and that is North Go figure and I can verify that actually is north And playing around with this thing, you can really get a gist for for just how sensitive it is to the Earth's magnetic field.

if I hold it vertical there, we'll see that the face if we rotate round will be at the 0 point point in North when it gives Zer volts. So um, really, this thing is is capable of measuring much lower magnetic fields than the earth. So when you're using this thing, you have to be extremely careful to uh, not only, uh, you know, ensure the thing is like clamped in place next to the thing that you're measuring. You got to zero it out and then switch it on and with the small tip, it really is, uh, quite capable of measuring uh, very narrow magnetic fields like the distance between uh, windings in a you know, a big wire wound inductor or something like that.

And you could also use it to measure uh, magnetic fields um, escaping from Holes and things inside equipment cases and stuff like that. So it really is quite flexible. but you got to be very careful on how you use it. You got to know exactly what you do it.

You can't just take a reading at face value because that's just crazy. So can we actually measure the absolute value of the Earth's magnetic field? Well, yes we can if we use this thing correctly. Now, Um, according to an online calculator, I use the Earth's magnetic field here in Sydney at the moment should be around about 57 micro. Teslas And of course, this thing um has an output sensitivity of 250 micro Teslas per volt.

So for 57 microteslas, we'd expect around about 228 M volts on here of 228 Vols. Let's see if we can get it. We're only going to get that when it's pointing North Aha, we almost had it by accident there. Let's we won't get it by doing that orientation, but if we shift it like that 90 directly down like that, we move it around.

We can't get that 228 yet. we're off. But if if we point it at the correct angle the Ma, we're going to take the maximum Peak value. there.

There we go. 225 226, 227, 228 230 Oh, there we go. We're pretty darn close. Pretty darn spot on to exactly what we should be getting for the Earth's magnetic field.

Awesome! And of course, once again, the calibration control has no effect whatsoever. I Can turn that because we're in an absolute measurement mode. The absolute measurement modes are the field and the wire. It's only when you're going into the PCB Trace mode do you need to use the calibrator.

Now One obvious use for this probe is for uh, tracing currents through ground planes and uh, tracing out shorts and stuff like that and uh, little very crude example of that here. I've got this wire on the back of this board here which snakes around like that straight through to there and it's actually um, shielded uh by all the other traces on there. but because this, um, doesn't is looking for a magnetic field in The Wire There's no current flowing through these tracers on the top. We'll be able to detect the uh the signal through this board down here.

so let's give it a go. You'll notice that as I move it it I can follow that signal around. If I keep going straight, we're going to lose it once again, you've got to get the Probe on the correct orientation. It's got to be perpendicular to the trace you're actually measuring, but we can see that wire going up there and we can trace.

Oh, there we go. can trace this thing around and if you're careful enough, you can actually Trace out. If you got a texture out, you could actually Trace out that exact path. And if you're careful all the way, so I can find shorts current paths, you know, if you got a short going through a chip through a power rail internally shorted on a power plane in inside a multi-layer PCB or something like that.

Um, you should be able to trace it out with this thing because it can find that signal anywhere because it's using the magnetic field of the trace. Now, what I'm going to do is try and attempt to trace out a real ground current on a PCB like this. And as you can see, there's a split PCB plane in there. So I've got my current going in over here coming out over here and it's got to go through that tiny little Trace down in there.

That's the only way that it gets from there through to there. There's the split ground plane there, so we shouldn't get any current flow around in here. We shouldn't get any current flow in the ground. fill down in there.

We shouldn't get any current flow down in here. We should just get the current flowing through there through that tiny little Trace there if you can see it and down around through to here. All right now. let's uh, try and do this now.

I'm using a 1 khz signal here, but it would work. Um, as for Uh DC as well. but uh, just remember, you've got the Earth's uh, magnetic field as well. So when you move this thing around, you know you you're going to get an offset.

uh, shift like that. So just be careful. But here we go. there's our reference waveform and we don't have to worry about the calibration on this pot at all we can because we we don't care about the magnitude.

we're just tracing currents here on this board so you can just you know, immediately start to use this thing and not worry about it. Now let's move it over this part of the ground plane and you'll see we've got absolutely nothing there at all. We can change the orientation and we get that offset, but there's no 1 khz signal. There's nothing flowing through that part, the ground plane.

but here here, there most certainly is. Once again, if we get the wrong orientation, it's going to vanish like that if we hold it vertical. But if we keep the correct orientation according to the magnetic field of how it should flow, then Bingo We still get the waveform so we can see this. see the currents going both sides of that hole there? No problems at all.

Okay, and it flows through here like this. and once again, it does. Some of it does flow down around there like that, but the majority of it going to flow through this top part here and it's going to flow up here and you'll notice that it won't flow down into that little fill that little void down in there. There is no current flow there at all, so there's nothing.

so you can see the current flowing through here. And likewise, there's going to be nothing flowing down here into these parts. Parts Down here, they're electrically shorted together, but there's no current flow and this is a great visualization uh learning tool as well as a real practical uh thing for determining. tool for deter, practical tool for determining where your currents are flowing in your ground planes.

And there it is. Flowing down there. and it's Look, it's not going down this little bit down here. it's not.

You know, there's not much, very little down there at all. Tiny little bit flowing through those two pads there. but as you can see, it's all going to flow through that Trace there, that one tiny little Trace which connects the two split ground planes and it's going to flow up here and all the way over to there and look down here. There's nothing in this little void down here because there's no way for it to flow.

And likewise, all the way over here down here here, there's nothing. There's absolutely nothing. we're getting that offset, of course, and if we zero that out, there's no current flow through any of this stuff down here, because that's where it flows through that bottleneck there around here and down into there. Bingo And if you watch uh Mike's video, he actually attaches a visual a like an LED to the output of this thing.

So the brightness of the LED changes with the amplitude of the waveform. That's pretty easy to do and then you'd be able to. You wouldn't have to use an oscilloscope, you'd be able to actually visually see it, or he hooked it up to a tone generator as well based on the amplitude of the waveform, so you'd be able to get an audible tone as it went across. That's one feature.

I Guess this thing is would guess it would have been nice to have is like an internal buzzer inside here, so you could use the thing as a Um tone Tracer basically to trace currents across a PCB but you know it's designed as a measurement tool. so I guess you could deem that to be a bit crude to have that sort of thing, but it might have been handy. and you also see in Mike's video how he got a he used a long camera exposure with the LED to get a visual map of where the current flows. I I Don't think I'll bother uh, setting that up I Haven't got time to do that, but I might experiment with that in the future.

But if you want to check that out, have a look at Mike's video. But as you can see, this is a really useful tool for showing where currents flow in a board. It's fantastic. And like I said, if you've got a a short inside a V or inside a pad in you know, a multi-layer like an eight or 10 layer board or something and they're notoriously difficult to track down.

But with one of these puppies, you can feed a You know you can feed some uh, you know, reasonable amount of current through there and Trace The thing down Beautiful. Love it! And of course one of the big uses for this thing is uh, probing switch mode power supplies so you can, uh, have a look at the switching waveform. So let's take a look inside this switch mode power supply here and we can see the output of the inductor there and we can measure the switch in frequency There It Is 40 khz between those Peaks there and it allows you just to take a look at without these waveforms without having to break into the circuit which is the traditional method to do it with these current probes and that's often very valuable and a lot of the time you don't need to know the absolute calibrated value. it's just good enough to look at the waveform and from the shape of the waveform, you can see if your Transformer is saturated or something like that.

so you can figure out what your circuit's are doing as you uh, change things so it's really quite neat. You can probe around and it's quite safe as long as you keep your you know your hands away. you've got your finger guard here and and uh, you can trace. Of course it's better if you have access to the bottom side of the board with the tracers, but we've got a wire actually coming out of here from the Transformer so we're able to probe that no problems at all.

So the Ier 520 in summary, Well, it's a novel bit of Kit I Love it I Think it's a really great Innovation it's got some limitations though. um, but it pretty much does exactly what it claims it. You can now measure current uh, without having to break into the circuit CU That's always been really annoying. You have to, you know, break your ground plane or whatever break your Trace break into it either with a current shunt resistor or with a loop of wire.

And then you got to get the oscilloscope current probe in there one of those clamp ones. Really kind of tricky business, and if you want to measure it at different points in your circuit, it's a pain in the ass. Now, if you just want to look at the waveform, just turn this thing on and probe it. That's it.

works. A treat, but of course you saw the limitations on this thing out. One of course is it's so sensitive that the Earth's magnetic field depends on the orientation can cause a an offset in this case, a DC uh offset of you know, like 250 Mill volts or something like that, which is equivalent to 250 milliamps. So you know you've got to be really careful with this thing.

It's not designed for microamps, it's only designed for milliamps, but it does have a pretty big dynamic range anywhere from 10 milliamps up to a few tens of amps, so that's not bad at all. And of course, you can use it as a hfield. Uh, Probe On its own, it's got the PCB Trace mode. It's got the wire mode with the tyroid.

It's got various bandwidths, does everything you want, but of course in wire mode, you've got to calibrate the thing and that is a pain in the butt. It's not that accurate I was able to get 10% for a quick test. You can probably get a bit better than that. Maybe you know if you get a tongue at the right angle and tweak it a bit.

but for absolute measurements H Not that great with just the PCB Trace mode, but at least you can do it. You haven't been able to do it before and that's it's worth its money just in that respect. So few limitations, but a really great bit of kid. and um, if I I think it's probably one of those things that if if you, if you have it lying around, you'll probably find more uses for it than what you originally intended.

I Can think of lots of instances over the years where I would have loved to have one of these. It would have saved a lot of grief, a lot of time and effort, and hacking up my prototype making it look ugly. So yeah, it's really quite nice. The bandwidth isn't huge, it's only 5 MHz Not as good as a proper wide bandwidth current probe, bit limiting if you're working on you know one or 2 mahz switchin Regulators or something like like that.

but at least you can see waveforms. Um, it'll be useful for tracing shorts stuff like that. So I Don't it? It does the job I Think it's great. Excellent bit of Kit thumbs up I Really like it.

um within its limitations if you want to use it now. price-wise um sale League Have got it for $798 us. Um, so under 800 bucks us picks you up one of these. Not exactly a hobbyist grade thing, but for any well equipped lab, it's probably worth having because there's no other tool on the market like it.

so looks like Aim TTI thly ther whatever they call themselves got the whole Market to themselves. It's brilliant I They recommend if you can afford it. I Think every well healed lab should have one of these things. They're really cool.

It' be interesting to see if any other manufacturers can, uh, come out with a similar type one I Don't know. it might be locked up in that uh patent with the special flux gate magnet Mini A flux gate magnetometer in there? Who knows, but certainly does the job. Recommend it. Hope you enjoyed it.

Catch you next time.