Hi, welcome to Teardown Tuesday. Got Another bit of test equipment today,, but it's one that you probably haven't seen before, and from a manufacturer you almost certainly haven't heard of before. What is it? It's a variable frequency converter from a company called Absopulse. And Yes,, they're from Canada! This is made in Canada, in Ottawa, in Canada.

In Canada's "Silicon Valley North", go figure, as they call it. This is a variable frequency converter, and what it does is it basically takes AC input on the back, and outputs AC on the front. But As you can see,, you can select the voltage. So What use is that? Well, it allows you to test the products which you've manufactured for various mains input voltages..

So That is a test that is often missed out by even a lot of major companies.. They Design and build their product-- mains-powered product, and they don't test it over the operational range of the input voltages. You'd Be surprised how many companies don't do it. And That's what this allows you to do.

It Allows you to adjust the mains input voltage to your product, so the output voltage from here. And This one does frequency as well, so that you can test your product that it works over the full operational range. And You can test its performance and efficiency or whatever it is that your product does over that mains-- or doesn't do over that mains Frequen-- that mains voltage range. But Not only that,, it can do frequency as well and that allows you to test your company's products, that it works in different mains regions.

And you may know of 50 and 60 Hertz as being the two mains frequencies used in the world. But There are other higher frequencies used in military systems and things like that, and aircraft and avionics and all sorts of weird and wonderful industries can go up to 400 hertz.. So This one I believe goes to 440 hertz.. So You can adjust the output voltage from zero to 260-- what is it? Yeah zero to 264 volts RMS at 500 watts, and 40 to 440 hertz output.

Very versatile bit of test gear. Essentially if you're designing mains-powered products. But Most labs won't have one.. And The thing about Absopulse, not only is it designed and manufactured in their factory in Canada, but they're a designer of high-reliability power supplies.

So These things are designed for high MTBF. High mean time between failutres. This One has over 100000 hours MTBF at a rated temperature. Pretty Impressive stuff.

And They proudly claim on their website that not only do they use the highest-quality components in all their products,, but they use design methods to optimize and minimize the components to ensure the utmost in reliability.. So This should be really well designed. This is not built down to a price, that's for sure. These are designed for high-reliability ultra-rugged markets.

So Hmm. You Know what we say here on the EEVblog. Don't turn it on, take it apart! But Before we do that,, let's take a look at the spec sheet here. And The model we've got, even though it's not written on it, is the VFC 500 Series.

And It's a variable output voltage and frequency, it's got electronic power factor correction, it's-- it is small and light, I've got to admit, it is quite light. It's got some true sinusoidal output voltage, it's got-- and fully isolated outputs, as you'd expect.. 500 watts output power capability, full electronic protection, and "field proven design topology". Excellent! The VFC 500 series is a variable AC power source designed to deliver power at a selectable frequency between 40 Hertz and 440 Hertz..

It uses PWM technology and generates a sine-wave output.. Typical Distortion less than 5%. Not bad.. It features full electronic protection, high efficiency, low output noise,, and it's fan-cooled.

Woohoo! The Use of components with established reliability results in high demonstrated MTBF. Is Manufactured in our own plant under strict quality control. Excellent! Now Let's have a look at the specs. It has a universal input voltage rate, 95 to 264 volts, and also a large input frequency range from 47 to 410.

Not Surprising I guess. The Power factor's a minimum of 0.97 at full load for the entire input range, various input protection schemes, inrush current limiting, varistors,, internal safety fuses,, low-- lower voltage than the specified minimum will not damage the unit. That can be, you know,, one of the cheap designs or something like that,. if you take the input below the 95 volts, it could, I don't know,, latch up, blow up, release its magic smoke, do whatever..

This One's designed to not fail at all. It simply does just not work with-- if the input drops below the voltage. So If you've got brownouts or sags or anything like that happening on your mains supply, it's not going to suddenly blow up on you. Fantastic.

It's got 1 hertz step output frequency from 40 to 440, 0.1% frequency stability. Eh, that's piss-easy these days. Even pwah-- I Don't know. 80 years ago, it was piss-easy to get 0.1% I guess.

Not that hard at all. True sinusoidal output, less than 5%. Which isn't bad, you know, like, these things are either like your cheap-ass square-wave ones, or your true sinusoidal ones. This is a true sinusoidal one, properly designed.

and yeah,, 5% is more than good enough. Line/load regulation maximum of +/- 5% Vout From no load to full load. That's pretty good. Output Ripple and noise, high-frequency ripple is less than 500 millivolts RMS over 20 hertz-- 20 megahertz bandwidth.

Well, I've done a video on that recently. Output overload protection, current limiting, short circuit protection, thermal shutdown. Blah blah blah. Hiccup at 4.8 amps RMS.

Love Power supplies that hiccup. Output overvoltage protection, 280 volts AC by internal power supply limiting, 80% efficiency, Aww man.. Temperature drift 0.05% per dif-- degree C, blah blah blah blah blah. Operates from 5 to 95% humidity.

MTBF, check it out.. 120000 hours at 45 degrees C operated, demonstrated MTBF is significantly higher. Now 120000 hours, that's like,, you know,, like more than decade. Pretty Impressive.

And There's the money shot for my Canadian viewers! Have To do it on the datasheet because, well,, it's not written on the unit! Why? And Here's the front panel, nothing fancy. On/off power switch, voltage up/down adjust, frequency adjust and some hot buttons for setting particular frequencies. Not Sure why it doesn't have 50, 60. You know? I mean geeze,, you'd think it would have that.

I don't know. 50, 100, 200, 400? What? Anyway. It's got isolated outputs. Neutral and PH, I assume-- I've never heard of PH, I assume that's like Phase Hot? Maybe? Anyway, that's the mains output, and ground, that would be just connected through to mains earth, if you wanted a Mains Earth referenced output.

But That's all there is to it. And on the back of the thing is no more exciting I'm afraid.. Universal Input, there's a fan which is actually connected to the outside, which is rather unusual, you don't see that a lot. It's got looks like it had some compliance-- well, some testing stamps, hipot testing by the looks of it,, something under there.

And some I don't know, production sticker or something from where this particular unit-- factory or something it came out of. So Let's rip this sucker open and see what's inside. And The case is rather nice. folded aluminium here.

It's not your usual steel case. So I Rather like that, it's lightweight, looks good,, nice bit of engineering. Feels Pretty solid and reliable. I Like it.

Now Of course, there are many design topologies to doing something like this. So This will be my complete guess, that it's going to have a basic input to-- basic AC input to DC conversion. And It'll either do that direct bridge rectifier on the mains input, or it may actually use an AC to DC converter, as a first stage. And Then the second stage of the output will be a DC to AC power inverter.

And of course, you've-- you know,, you're familiar with those, you can buy them for next to nothing for converting your, you know,, 12 volt car battery into a mains output. But They're usually pretty crusty, and I have a DaveCAD drawing right here, which shows how crusty it can be. You Can basically have your 12 volt DC supply or whatever it is,, your step-up transformer like this,, and you can have some switching N-channel MOSFETs here, which alternate-switch the-- well,, the primary side in this case, of the transformer, and the secondary side being the AC output. But Of course, with just that, you're just going to get that crusty square-wave on the output, you're not actually going to get your sinusoidal output.

So This thing will of course have, you know,, sinusoidal drive control to actually do that. And They typically don't have any feedback as well,, because the AC voltage is fairly accurately set by the voltage of your DC rail, plus the ratio of your transformer.. So These things, actually,, even though they've got no feedback,, can actually be quite accurate in that case. But They are square-wave, they are crusty.

Now, this thing of course won't-- it'll have the step-up transformer of course,, but it'll have sinusoidal control. And It says it does PWM control. In Fact,, what does it say? It says it uses PWM technology and generates a sine-wave output. So The PWM might just be used to generate the sinusoidal waveform.

I Don't know, eh.. There's probably-- you know,, likely some sort of microcontroller in there as well to handle the display and probably generate the required frequency with PWM. But I Don't know, there are many other ways they could do it. They could certainly do it.

Some clever scheme like direct AC to AC or something like that. But I Think there's going to be that two-stage process with DC in between. But, there's only one way to find out. Screwdriver Time.

So What we've got is 6 screws on the top, and that looks like it holds-- well, it-- there's like vertical heatsinks inside and it looks like-- or mounting aluminium mounting boards or something in there, so, like a, you know,, separator.. So That could be the two halves, maybe there's one half-- maybe there's one board in there,. there's the 6 screws,. So maybe there's one board in there which does the AC to DC conversion, and then there's another board in there which does the output DC to AC conversion at variable frequency.

So Let's undo this thing. And As I said,, should have really high-reliability components. We won't find any no-name caps in here I'm sure. They'll be super-high quality because this thing is not built down to a price.

Price really has. No,, you know,, the designers of this thing weren't thinking about price. They weren't constrained by price when they were designing it I'm sure. So They're free to just choose the best possible components.

Alright, it is apart, so let's lift-- this should just lift off, and... Tada! It does. And Yes, folks,, we have two boards in there. Well There's one front-panel board.

Of course,, that was kind of a given. But We have two boards in there, as I expected. And Yeah, I Think one is certainly going to be the mains AC to DC, and the other's going to be the DC to AC board. There's actually quite a bit in there by the looks of it.

Whoa, I See a bodge cap already? And-- didn't expect to see a bodge cap, but I see lots of silicone umm... hot snot around the place. And Well. Interesting.

Let's check it out. Now There's one thing I noticed first of all, and I don't like the looks of it. Now Here's the terminals-- Here's the ground terminal on the front, okay? And There's the green and yellow earth wire coming out from that, Okay? And It goes over here, and then it's connected over into here, it's got crimped, it's got a shakeproof washer, brilliant, Okay., And Then, okay, that is then screwed down-- it goes onto this, which is then screwed onto the bottom plate, and then of course the bottom plate, you know, is the entire chassis for the thing. But If you have a look inside here,, there it is..

There is-- I've undone the screws on the back of this thing. There is no connection onto the earth lug of that mains input filter there. Look at that! Nothing! It's not connected at all. What they're relying on is-- I-- I haven't see-- look! They're relying on the fact that this mains filter, okay? It-- either it's got a dicky connection on the side there, or it's got some-- probably can't, you can't get in there and see it, but it's got some metal on the back in there.

Because the screw which goes into it, which has a shakeproof washer, no worries,, they've done well there. But Then that's connected onto the plastic there. So It's not even making contact. So It's just the-- it's just the press against the metal of that into the threaded screw hole.

I mean-- I mean if that plastic was overmoulded a bit, it may not even make contact at all. I Don't like it! Why Have they done that? It Seems retarded. It Seems so well engineered at first glance. Everything Apart from the lack of the mains--, why wouldn't they just put the extra crimp wire on there, and wire it through-- and wire it through directly to the front panel? I Don't get it.

Alright, So what's going on here is pretty much what I suspected. We've got our 240-- Our mains comes in here, goes to our front panel, switch over here,, and then goes over to the top of this board over here, so it goes into this part of the board,. we'll take these boards out and take a better look. And This is the-- I Believe this will be the AC to DC conversion, and these big thick black and red wires there which go from this module over to this module are the DC output down to there, I'm presuming.

But Curiously, they've got this control board here, adjustment pots with-- they've put some setlock on there. When they've adjusted that, it looks like they've really adjusted-- the don't want anyone to adjust that put there either. So-- and there's another one down on the front panel, that's for the display accuracy. The Display ADC and measurement accuracy I believe.

But This control board in here is rather interesting. Which Goes through to the front panel control here. So mmm. Maybe-- is this-- are they generating the required sine wave on this board, and then feeding it over to here? There's some-- we've got some optocouplers down in there by the looks of it.

And-- I don't know. It's-- the topology of this thing. Well There was certainly no shortage of screws holding this plate down. 10 of them, all with shakeproof washers.

Excellent, they've done well. And Tada! There it is.. There's our ma-- there's our AC input module, I guess we could call it. Now This thing looks really messy, of course,, and it is I guess.

Because, you know, it's got Silastic everywhere to sort of hold in place. all of these vertical boards, vertical components all pushed into place. So It really is quite-- quite a messy design. They've got all the controls, most of the control circuitry on vertical riser boards here.

One Here,, there's 3 separate boards there, four, five, at least, yeah,, so it looks like 5 separate vertical control boards there, with all of the main power stuff on the bottom double-sided board. A few miscellaneous stuff around there, of course. But Yeah,, most of the-- most of the control for that, on those vertical boards. And It is very messy.

But They've gone to a lot of trouble to mount-- check out the mounts for these power devices. These Look really interesting. Huge Screw with shakeproof washers and some-- looks like some sort of custom plastic clip on that. And into that vertical heat sink there.

Really Really interesting. and look,, they are genuine. Infineon 47N60C3 or SPW47N60C3. And Let's go to the datasheet.

Cool MOS Power Transistor. 650 volts, RDS 0.07 Ohms, 47 amps, worldwide best Rds, whaha. Revolutionary High-voltage technology, ultra-low gate capacitance, 650 volts by the way is very, very high. So awesome.

Periodic Avalanche rated, extreme Dv/dt rated. Ultra-low effective capacitances. Woohoo! Top of the line MOSFET Here folks. So There you have it, some sort of custom sort of plastic retention clip there, that goes over these power.

MOSFETs. Really Quite nice, and they've used it a couple of more times over here as well. Beautiful. And I Think I might know the reason why they've gone for this retention clip like this.

It's-- I Think it has to do with the ultra-lo-- high reliability nature of this thing. Or possibly even the high-voltage isolation and stuff like that. What they've gone with here is a-- you can see the Sil-Pad there, and that is a complete Sil-Pad sheet. Going Right across and it even wraps around.

You Can see it wrap around the side. they've-- around the sides of this thing. So They've-- you know,, they certainly haven't skimped there. But It means that they don't use the traditional hole here to put the screw through like that.

Because If you do that, then you've gotta have the screw with the insulated washer, but it's-- like, we're using here, but it's going to be much closer to the metal tab on the back of the heat sink. So There's less clearance there, less reliability, less-- in terms of your manufacturing tolerances. Of Course, by the way, in there,, if you go through here, you've got to have a hole in your Sil-Pad and all that sort of stuff. So This way they don't, they use a complete Sil-Pad sheet in there, unbroken, and then-- so they shift the screw up to here, and then they've got no issues with, you know,, gap tolerance and high-voltage arcing or, you know,, anything like that, or in terms of manufacturing tolerances being out and some units being slightly lower, you know,, high-voltage tolerance specs than other ones.

Nice! Alright So let's start at our mains input here. Here It is,. we've got it going through a-- look like a common-- small common-mode choke here, by the looks of it. And Then we've got this vertical fuse, check it out.

Vertical 3AG Fuse, look at-- look at that. I've never-- sort of-- well, no, I've occasionally seen that. Not Going to say I've never seen that, but it is quite rare. Once Again, all these vertical components, they're all Silasticed down, they've really gone to town.

Someone Had fun with the Silastic gun at the factory, that's for sure. Check Out the-- is that a MOV? No, that's a high-voltage cap there and they've Silasticed that down,. this-- another big common-mode choke they've got here, these another big series inductors by the looks of it,. And there's our suppression cap from the neutral through to the input earth down there,.

and that, of course goes to this shaft here. and that goes off to the chassis. And There's our input varistor protection. They've gone to the trouble to put-- what is that? It's not quite ceramic, I Don't know what they've put around the legs of that sucker, but it's not like a ferrite material, so I'm not entirely sure what's going on there.

But That's a big-ass varistor by any stretch.. And Then we go over here, we've got more mains-rated caps all in here,, and then we've got this huge cap, which we'll take a look at here,, and our first switching transformer. And That's input 90-265 volts AC, output 2x200 volts. Aha! 1.5 amps each.

So It looks like we're going to have a high-voltage DC supply here. And That should be-- we'll get more evidence of that, of course, with the output filter caps, when we take a look at their voltage rating.. Now What we have here, folks is a high-voltage high-reliability metalized polypropylene cap. And They've used this instead of a more traditional electrolytic cap for ultra-high reliability.

Once Again,, huge standoff, and they've gone to the trouble to put insulation on the leads there. Aww, brilliant. Silasticed It down. I Mean it does look ugly, but hey,, you know, this sort of thing works.

So What the designers have though is, well,, this is our critical cap on the input side to our main switching transformer. Here,, let's get an ultra-high reliability cap. And That's what they've done. And We've got a board in there with a whole bunch of power resistors on it, probably all paralleled up.

And Once again,, some more 47N60s as well down in there. We've got 2 and possibly a third one on the other side here. I found it, I found it! There You go folks, Made in Canada. And They haven't mucked around with the isolation either.

Check out that. They've just gone primary/secondary isolation? Let's just route out the board, no worries. This Transformer here, of course, isn't our main isolation transformer,. If you have a look at the bottom here,, there you go..

There's just the isolation slot here, which is just separation mains earth from the rest of that, but look, it goes straight through. So That's not actually a-- the main switching isolation transformer. All of this part would be part of the active Power factor correction circuitry I believe. So If you have a look at the back of the board, you can actually see the flow of this thing.

Here's our mains input over here,. We've got our input filter and our common-mode chokes and stuff like that. Then We've got it going into our active Power factor correction circuitry, which would be all this stuff in here. We've got high-current stuff going around into our primary-side of our main isolation switching transformer here.

Here's our secondary side of that,. You'll notice that that's also isolated down in there,, but they haven't bothered to cut a slot out of that one,. but that's a massive isolation slot, they're not mucking around there at all.. And Then we've got our output bridge rectifiers here.

We've got a big output common-mode choke here,, and then our output filtering. And goes straight to our high-voltage DC output terminals. And The wave soldering here is also first-class, even on the big power transformers. I like it.

And That's a very common thing to,, you know,, goof up. Your Lower quality manufacturers. They'll either be soldered by hand or, you know,, really crusty wave soldering, and you won't get good-quality joints. And Of course they've gone for the best, Nippon Chemi-Con capacitors.

KMH series, 105 degrees C rated, 450 volts, 220 microfarads. Beautiful. They would be genuine, bet your bottom dollar. And on the main DC output just near the output connectors here, once again, Nippon Chemi-Con, exactly the same model, KMH.

250 volt, 560 microfarads. So, this definitely is a high-voltage DC output power supply. It wasn't the low-voltage, which I thought probably would have been the least viable option for this. So They're outputting, on these two terminals here, outputting-- yeah,, no, I can actually touch that.

These have got bleed resistors on there, check it out, not a problem. Safety First folks. I'm a professional, I know what I'm doing. So Yeah,, they're outputting high-voltage, like you know,, 250-odd volts on these terminals here.

Check Out how they've vertically stacked those two diodes there. Absolutely Fascinating, and look at the hot snot there. Aww Man. Somebody's had fun.

Actually, if we have a look at the output here,, check out that. That's a zero-ohm jumper link there. And What they've done, is actually these capacitors are in series.. So Here's that-- here's the two output terminals, it's only got two, positive and negative.

Then That jumper link joins the-- there you go, joins the two caps like that, so they're actually in series. So We've got a 500 volt cap there. And They not only act as bleed resistors,, but they act as ballast resistors as well, to sh-- ensure voltage sharing across the two caps. Now This is fascinating,.

look at this.. This Little board here that just holds this capacitor and nothing else. It's got wires coming off here, and a connector coming in here, is held onto this board via two plastic clips there. There's no electrical connection between these two boards.

It's purely just like a physical mounting thing. So Why they've done that, why they've bothered to go "well look, our cable's going to-- well, our-- our cable's coming from all the way over here,. it's going to be wired into here,. they've cabled tied it going into this board,.

this board will retain on this board, and we'll have a separate connector". Like-- it's like it's maybe designed for servicing or ease of manufacture or something at the production stage? I'm-- something like that. I Don't know. And It looks like they've bodged in a little transformer or choke in there, like just sort of, you know,, bodged in between this transformer over here and something else over there.

I Don't know. Aww Man,, what a dog's breakfast. So We've got our main switching isolation transformer, and then we've got two groups of four diodes in there, so it's-- they've got two separate windings out of that thing. So There's our bridge rec-- bridge rectifier one, bridge rectifier two.

This is just a big output uhh, inductor, and then it goes into the caps, of course. That's why there's no isolation at all between those. Because They're just inductors from there to there. And I Almost forgot to mention the thermistor on the back of these two main switching power MOSFETs here.

Very nice. So, overtemperature protection. So What we've probably got here,: these boards in here would be part of the control for the active power factor correction stuff around here, and then this circuitry down here would be our main switching control for our main AC to DC converter. So Hence, we've got a couple of optoisolators in there, getting some voltage feedback by the looks of it..

There's that part of the isolation down in there. And You can see that on the board, it's separate, they've got the two connectors on the bottom there. You Probably can't see that,but there's-- that's the isolation gap between primary and secondary side of the main switching transformer.. And Here's our second DC to AC inverter board.

Not Ne-- not really as interesting as the other one, but eh,. still. we can get a look at some chips in there and have a look. But Once again,, aww look, person with the hot snot gun has just gone ballistic on anything over 10 mi-- millimeters tall.

Hah, everywhere! And Once again,, if you have a look at the back of the board, you can see how it flows.. Here's our high-voltage DC input here at, what was it, 250 or 300 volts or whatever? And We've got some more bulk input capacitance here, and then we've got our switching transistors here. You'll notice that, you know,, nothing sort of-- you know,, we've got ground going off and-- going-- snaking through this part,. But the-- basically no more high-current flows into this part, because this is all the control circuitry.

So It basically loops-- all the high-current stuff just loops around to our output terminals over here. So We've got our switching MOSFETs in there,. there's 4 switching MOSFETs, there's a whole bunch of diodes in there, and, what,? we've got our output transformers around here, and there's our output. So This would be presumably the-- we'll have to have a look at the chips.

Ooh, a bodge-wire, look at that, hello. Hmm, that's not good. Anyway, yeah,, this would be our control circuitry for the inverter and possibly the sine-wave generator as well. I Don't know, we'll have to take a look at the chips on the top.

But Yeah, you can see how it flows nicely in here, through there, through the power switching transistors here,, through the transformers and out.. No Surprises on the switching. MOSFETs, same 47N60s we had on the main board with the high-voltage retention clips. And Check out down in there, we've got around the source lead of the MOSFET, cheeky little ferrite there, just to take the edge off the switching noise.

And First cab off the rank, there is a UC3644N. And On a very quick search I Can't find any info on that at all. Woohoo, some 4000-series CMOS porn! Classic 4049. Beautiful.

An LM311, that's been slimed! And We have two IR2110 MOSFET drivers. They're upside-down so they're not going to work anymore, all the electrons have fallen out, What a bugger.! This-- reason we have two of those is because we have two sets of power MOSFETs there. And Check it out,. we have ourselves a current transformer here.

You may have-- you may remember this from the Smart Meter teardown. We've basically got a single turn going through there, a single wire through,, and it's able to measure the output current. Beautiful. And On the rear side of both of those MOSFET heat sinks there,, we've got ourselves a couple of cheeky little power diodes sharing the love.

And Our main input caps here aren't Nippon Chemi-Con, they're Cornell Dubilier 270 microfarad 450 working volts. 105 degrees C rated, high temperature versions of course. You'll note another 3AG fuse vertical 3AG fuse down in there as well. Once Again, held in place by hot snot, beautiful.

But Yeah,, they are one of the world leaders in capacitors as well. So They certainly haven't skimped there. They Might look a bit plain, but aww, they cost a fortune, folks.. And We've got ourselves another thermistor down on that heat sink.

But Curiously on the matching heat sink over here, no thermistor. Why They've got it on. only one, I don't know. Once Again, we've got our high-reliability mettaline polypropylene cap on the output here.

They've spared no expense. Huge Output choke here, by the looks of it.. And Some more output-- the main output transformers here. And, well,, that's about it, folks..

Oh, we've got a couple of bridge rectifiers dow-- no, they don't looks like. No, look at that! They've paralleled them up. They've paralleled up the diodes there just to get some extra current. Hope They're matched, aww, they'll share reasonably well,.

good enough for Australia anyway.. Good enough for Canada! There You go. But What we don't really find on here is the, you know,, the sine wave generator. The Frequency control.

So It must be on the main board. Well, the front panel board. And Here it is! Well They're certainly fond of through-hole technology, aren't they.? There's not a single surface-mount part in this entire product. So What we have here are 4 large DIP parts, with labels on them.

So Presumably they're all microcontrollers. This one's VRMS8, this one is INDF5, for-- maybe for indication? Aha! OSCVFC1. Oscillator variable frequency, and CODF7, hmm. And It's very difficult to get in there and see that, but surprise, surprise folks,, it's a PIC 16F872.

Another PIC for the indicator, the one we just looked at was the RMS, so it'd be measuring the RMS voltage and displaying that. And This is your-- there's our variable frequency oscillator. They've dedicated PICs to each individual task. Umm, COD? Not sure what? COD is.

Control something? I Don't know. Alright, I Couldn't help myself, there you go. PIC16F872, that is the COD chip. So I'm sure they're all identical or variations of various 16-bit PIC chips.

Yeah, even the variable frequency oscillator, same device. And That RMS chip we had over here is obviously dis-- driving the display, because it goes down to this connector here, which then goes down to the second board, which then-- there's nothing on the second board, by the way. It's just the displays and the switches. And that displays the voltage-- the RMS voltage on the front.

So There's actually a second tap coming off the output. And There it is,. there's the output voltage coming out there. There's the N and the PH, the phase hot or whatever it is.

So It actually measures that using the built-in ADC, and that-- and it can also display the frequency. So COD I Don't know, maybe control output display or something? IND indicator or something,. it looks like it's driving-- that one looks like it's driving the frequency display, so indicator is like the, you know,, frequency measurement and display. And We've got ourselves a couple of optocouplers down there, they're A3140s, 8 pin DIP versions.

And There's our output there to drive our two outputs for our power. MOSFET. So That's our PWM-- that'd be our PWM output driving those power. MOSFETs.

Well There you go, that was interesting. All I've got to do now is put it back together. And It's time to power this sucker back up, and see if it works. Let's go, will the magic smoke escape? Nope! Not A problem.

Look at that. 110 volts, that's probably the last voltage I set it at. And There it is, bang-on 157 volts, 49.999 hertz, not a problem. Let's go to 50-- 100 Hertz, Boom.

200, 400 hertz output! Ooh, that voltage didn't stay all that regulated, did it? There's a little bit of discrepancy there when you switch up in frequency between the set voltage, but there you go. And We can go up all the way to 440 hertz if we so desire.. And You can see the voltage changing a bit with frequency. It's no load, it'll perform slightly different with load.

But It's probably-- well, I'm sure it's within spec. Now One of the interesting things about this is that you can hear the switching frequency. So I'll put my lapel mic right up to the side of the unit over here. I'll increase the gain and I'll change the frequency and see if we can hear it.

But You might need really good, you know,, low-frequency response speakers and/or headphones to actually hear this. But We'll give it a go. So There you go,. that is the Absopulse VFC 500 series.

Hope You found that interesting, and if anyone has a schematic for one of these puppies,, it'd be very interesting, So please post it-- a link to it in the forum or the comments, if you can possibly get one. I Doubt it,. they don't sell these things in huge volumes and I don't think they're about to release the schematics. But You never know.

Or If somebody from Absopulse is watching and they want to share the schematics with the world, share the love, then please do so. So There you go, I Hope you found that interesting. That's a variable frequency converter. Very Unusual bit of, well,, power supply test gear I guess you could call it.

And from a company you almost certainly never heard of. And made in Canada which is almost certainly you never hear of either. So There you go! If You want to discuss it? jump on over to the EEVblog forum, and if you like Teardown Tuesday, please give it a big thumbs up. Catch you next time! captioned by Sen in Canada.