Hi. It's product review time. We've got the Kogan KA 32p, 30 volt, 5 amp programmable power supply and this one's rather remarkable in that it's probably one of the cheapest programmable supplies on the market. Um I Got this from Trio Smart Cal Uh here in Sydney and they have it for $199 Australian dollars? that's for 150 W linear.

This ain't switch mode. this is a linear program Aable USB Serial power Supply Brilliant. You can, uh, pick it up cheaper Us dolls. but beware it is.

uh you if you're in Australia don't buy the US one. It's non switchable, 240 volts only as we'll go into. but yeah, these things are quite remarkable. And I've already done a tear down of it, so check it out here.

Click the link. Now the first thing you notice about it is that it's this nice compact Slimline vertical format so it doesn't take up much footprint on your uh bench itself or uh, up on your rack uh, space above your instrument rack so you can considerably put you know a couple of these side by side. They cheap enough to buy a few anyway, and uh, have a very versatile Supply So it's actually I rather like this format for uh for power supplies, it just seems to work uh and it's quite a sturdy Uh instrument. And if we take a look at the back here, we've got Uh USB and serial, both optically uh isolated from the input.

The USB is, as you saw in the tear down, is Uh, is electrically connected directly to Main's Earth but apart from that, it is Uh it is optically isolated from the output. Brilliant. One large cooling fan on the back IC input as I said 220 volts only. the US versions would presumably be 110 Vol only.

So if you buy an internationally, just beware you get the right version. Tra for young players and the thing's pretty hefty as well due to the large linear Uh Transformer in there cuz this is a linear Supply not a switch mode. it is Transformer is centered in the middle there, so the weight distribution is pretty even. It's a fairly sturdy Uh Supply though in terms of uh, you know the cases: reasonable thickness, reasonable quality, and uh, yeah, I don't mind the build quality at all.

certainly for the price. and if we pair it up here, we've got independent voltage and current readouts as you'd expect on any good Uh lab supply, plus a whole bunch of indicators. We got over voltage protection, over current protection, which are separate modes. You can select uh, constant current mode, constant voltage mode, and whether or not the output is off or on because it's got a soft Uh output switch, and uh, up to five different memory recalls.

although curiously, there are only four memory recoil Cor buttons here, but there are five LEDs go figure and you can tell it's sort of, you know, low cost, a bit slapped together. the uh, the face plate they've put on here doesn't quite line up with the uh, seven segment display in there, so it's all a bit out and it's all a bit wonky. But you know I mean for the price? H You're not going to complain about little stuff like that, but um, it it does have it says it's a 30 volt, 5 aamp Supply but the display and the adjust range is certainly capable of going up to 31 volts maximum and 5.1 amps maximum. So it's got one Optical rotary encoder knob which feels eh, just like any other, you know, cheap Optical rotary encoder, but certainly adequate for the task it's got, you know, reasonably good purchase.

It does have the little finger in there hold in there so that you can wind it around and around. pretty nice. and uh, the buttons are of course the uh soft um PCB uh Mount buttons as you're familiar with them. my my one's a bit sticky on the M2 button, you got to push it a bit harder than the others, but eh, you know I mean what do you want for the price? Um, it's got the four uh, memory buttons here.

They store uh, constant voltage and constant current as well for each one. So if you wanted say uh, 3.3 volts at 1 amp, you could do that and store it in there and uh, you can recall them with a single uh press. And the lock button allows you to lock and unlock the keypad. So if you've got your supply set to 3.3 volts and you don't want to blow up your you know, expensive $10,000 board you put the lock on and doesn't matter what you do, watch you press the recoil buttons or the adjustment or whatever.

um, it won't affect the output, it locks out the keyboard excellent, Um, it's got over current protection as well, over voltage protection excellent and an output onoff uh button which will try out and uh, current and voltage adjustments which adjusts the digit and uh output. It's only a single output power supply of course. um The Binding Posts are reasonable quality I don't mind them at all. they do come right off.

They've got the banana uh plug in there. They've got the hole for the wire as well, so let's check those out. And uh, it's got the separate Earth terminal as well and they are a standard Pitch Industry standard pitch so you can plug on your BNC connector or whatever. Brilliant! And it does have a real clunky onoff power switch which actually switches the Main's primary.

so it's got pretty much every feature you would want in a single output uh, lab supply and it's but it's also programmable this. It's also available uh, cheaper in a nonprogrammable version, but I Don't think you're paying that much more for the Uh for the programmable one with the USB and Seral and we'll try that out later. So let's have a look at Uh some of the functions here. It's got the Onoff switch and what? I Really like here? Okay, the Uh output right? It's telling us the output is on so voltage is Switched onto the output Terminals and so it it switches between displaying the output current and when you turn it off, it switches to the adjustable output current.

Great! That's exactly what it should do. There are some supplies which don't do that and it's a pain in the butt and you've got to short the output to adjust the current and things like that pain in the ass. This one does it very nicely and to adjust the voltage and the current never thought you'd ask you hit voltage and current and it jumps between the two displays and flashes the digit there. So let's adjust the voltage and we can use the left and the right buttons here to select the digit.

Oh what happened there to select the digit that we want to adjust? And no, it doesn't just adjust that digit. So if we go in here say 1 Vol We can adjust it like that and it goes all the way down and operates on that one volt. So we can go over to here here. 100 molt resolution great and we can go over here 10 molt resolution: Excellent.

Um I Don't notice any missing or doubled up. Um jumps there on the optical rotary encoder. Seems to Seems to do the business, but uh, like if you leave it that say you know six there for example and you jump over it doesn't round it off, it actually just bumps up that digit like that and it does exactly the same thing for the current. So you go down here and you can adjust the current all the way down to 1 molt resolution like that.

So the Uh resolution. Unfortunately, on the Uh voltage scale it I would have liked to have seen it. Um scale up there and go. you know, 9, you know, XXX volts.

So we got 1 molt resolution, but we don't. We get a fixed 10 molt resolution. Bit of a bummer there. Uh, the amps.

They get away with it cuz you don't need better than 1 molt resolution on the amps. Really? So you know that's not that big of a deal. But uh yeah, it goes all the way down to Z volts and as you can see, it automatically switched out of that mode there. if we press it, enter it.

it'll automatically jump back out if you don't touch the optical rotor encoder in like 5 or 10 seconds. So setting and adjusting the voltage and current Works quite well and quite intuitive I Like it. As for programming the Uh constant memories here, we can just if if we want to recall them. For example, I don't know what's programmed in here yet? Let's have a look.

You got this horrible buzzing sound. Not sure if you can hear that here. Here we go: I'll put the mic up close to it and see if you can hear this. It's a pretty horrible sort of sound.

I don't really? Uh, I don't really like the buzzer at all I think they've uh, really goofed. Uh, that one up I think but uh. anyway, it's a bit sick sounding. It just doesn't instill a lot of confidence.

Um, but to recall the uh program memories here? Um, we've it looks like it's automatically programmed. No, we must have pressed M1 before. Anyway, let's press say M3 23.2 Vols at 4.37 amps. Well, let's play around with that.

Let's say we want 12.2 Vols and we want you know 1.07 amps. Well, we want to program that into M3 you just press M3 hold it down and that should program that in there. So there it is, 12.2 and 1.07 works. a treat And of course you can see which mode you're currently recalled here.

So I don't know why they've got M5 here. Um, I was playing around with one at Trio Smart Cal and we sort of managed kind of to get into M5 but I don't know. Maybe you can program it via the serial port or uh, or something like that. but there's only four matching buttons on the front panel.

but that's more than enough really. And of course, if you're here working on your board and somebody comes along and accidentally, uh, you can't accidentally, you know, adjust it with the uh uh knob which I really like. You know if you accidentally brush it and uh, you know it doesn't adjust at all without the Um keypad lock on there. But certainly if you come along and accidentally press that, oops, you know you could fry your board.

Um, so that's bad. So that's why you want to put the lock on. So you just hold down the lock button and once again, a pretty sickly sounding beep there. But now now you can't do anything.

can't do a thing. It totally locks out the keyboard and wonder if it locks out the serial. Port Don't know, um, but you just hold it again and bang. We're back to playing around with it to our heart's content.

Now it appears to have a temperature controlled fan in it. and of course I've got no load, uh on here at the moment, but it's enough to be a little bit annoying. Mine's got a slight, it seems to have a slight rattle, uh to it or something like that I don't know if that's uh, normal or not, but anyway, just bear that in mind. these certainly aren't silent.

It doesn't switch off the fan with no load, and I've had this switched on for about 10 minutes, drawing no load at all and that is reasonably warm under there. I'd estimate 35, maybe 40 C already on the base plate. and if you you really don't like that sickly beep sound, you can actually hold it and for a couple of seconds and it will switch off the beep sound. Excellent.

I Like it. That's the way it should be now. I'm having a read of the manual here, which is all in English by the way. and it? you know it's pretty, uh, pretty darn uh, basic stuff, but it has nothing on the operation of the overcurrent protection and the over voltage protection.

Or at least start setting it whether or not it's even setable at all. And uh, I haven't really been able to figure out how it actually works. Now for some testing, we've got the right tool for the job. the BK Precision 8500 300 W Programmable DC Electronic load and this thing is just as accurate um, as my uh, you know, Fluke 87 multimeter.

So the voltage and current readouts are super accurate so there's no need to even, uh, hook up a Fluke meter to check the accuracy on this thing. This can do it. No troubles at all. Um now I've just got that uh connected directly uh into the uh load of course, straight over so we can check out its uh, constant current performance and uh, its turn on its load, transient performance and all sorts of stuff like that.

And then I've got a uh a banana plug to BNC adapter going into my Agilant 3000. Okay, let's uh, check the display accuracy, voltage, and current for different, uh, constant power levels. So uh, I've got it set to constant power. one watt.

little tiny one watt load at the moment. so we're in constant, uh wattage mode. You'll see a little CW there. so we'll be drawing a constant one watt.

my current limits right up. and uh, one volts. Let's switch the output on and you should hear the fan switch on. By the way, let's go wham? You could really hear that.

It's so you know when it's drawing. uh, you know, one amp on the output, one vol? of course, one watt. Then uh, let's have a look at the correlation of the displays. Pretty close to spot on.

Beautiful. It's almost, uh, practically at least significant digit stuff. I Got no problems with that at all. Let's increase the voltage and uh, you can see it's the fan just dropped a bit there so it took some time.

So 5 Vols a spot on. and yeah, the the displays. I've got no issue with this at all. Oh 10 volts.

we just heard the relay click in then I'm not sure if you heard that, but uh, you know it's It's pretty close little bit out on the current display, but you're only talking about a couple of you know a few milliamps. I mean it's um, it's quote that's well with Insight it's uh, quoted accuracy by the way. Anyway, let's change this. Uh Power oneing.

let's go up to something a bit more substantial. Let's go up to 10 watts. T Oh I Love this. This constant current mod ah, it's a thing of beauty really is got to have it exact just because we can.

So drawing a constant power of 10 watts. Okay, now we're talking and uh, here we go. 3, 2, three. Yep, it's all pretty close to spot on.

I Like it. Let's drop down to another relay setting 555 timer category and we're only 5. MTS out there, it's not much. It's not bad at all.

so that fan just really kicked in again. that fan is really quite loud. Not sure if you can hear it, but wow, yeah, you wouldn't want that running uh, all the time that's for sure. It is quite loud.

All right. let's try and test the maximum load of this thing. Let's set it for constant current mode 5 amps. there it is and uh, we'll switch.

It On full Voltage out here got 31 volts and uh, the current uh uh, limit is set to the maximum there. so well, let's switch it on and see if it can deliver that. and well, it, uh, certainly seems like it's able to. there's that's a full 150 wats and if you're curious to see what's happening at a constant 150 wats on the output, well I've got it.

Uh, AC Coupled, uh, Bandwidth limited. We can switch that on, but we'll have the bandwidth limit on and uh, I've got it in high resolution uh mode as well. There's regular mode of course, but let's put it in high reses mode and uh, that is working. A treat that's 10 molts per division.

No dramas whatsoever now. I Think there's some funny business Happening Here Constant Power I Switch it on and I'm only getting 2 volts at 5. And there it is. 2.

Which is really quite strange. Let me try that again. So I'm not sure what's going on here. Let's switch my load off.

Bang. We're back to 30 Vols uh output now: 31 volts. And uh, let's set that to. instead of constant power.

let's set that to uh, constant, uh, constant current. So let's set that to 5 amps bang and we'll adjust our vol volage to 30 volt at 5 amp constant current. Let's give that a try. so we're in constant current mode.

Okay, we're drawing our 150 watts. Let's try the load. Switch on with 150 watts in constant current mode. Now on my electronic load.

let's give it a go wa look at that. Woohoo! What on? Earth Is that? Is that the power supply or is that my load? or is it a combination of both? Plain funny business. Let's try it again one more time. Wow.

third time and that's with a constant current load. So that is rather bizarre. I Mean you know there's no overshoot there. You don't have to worry about that.

Um, but let's uh, take it down to 15 Vols and see what happens. All right, right? 5 amp constant current load 15 Vols output. Switch on and bang. There's nice little kink in there.

Look at that boing, but it does not overshoot. Let's do it again. No, still doesn't overshoot. so the ramp up.

uh, performance. That might be where it's start switching. I Mean it shouldn't switch a tap on the Transformer because it should know that it's it's already in 15 Vol So now I've got it set to 50 W Uh, constant current load at 15 Vols output. And that's our switch on performance.

Nice. and you know, relatively clean. No overshoot there little bit of a step thing there, so let's try that again. But watch this sometimes.

I'll zoom out and let's press the button here. Our load Onoff button. so let's capture that again. but look at that, it's jumped up and then it's ramped back down to2 Vols What's going on here? There's definitely some funny business going on here.

I've got 4 amps constant current set with a uh 50 wat constant load so we should expect that 15 Vols you know, 3.3 uh amps or so and we switch it on. And and sure enough, that's what we get. But we do it a few times and we'll eventually get to a point where it this voltage will drop down. Not sure if it's like the some sort of over the over voltage protection mechanism kicking in.

it shouldn't cuz we're not, we're not doing anything but. ah, I'm having a hard time there. We go. Bang Got it? What's going on? And if we switch it off, of course it will, uh, switch back on with the load off.

but it actually retains the Uh settings we've got storing them in the E S prom in there, which is excellent. Um, but it doesn't switch a load on. so um, that's that's that's a good thing. So you've got to manually switch it on with the load button.

bang. All right, let's check some uh switch on performance. now. What I've got is uh 3.3 volt.

typical Uh power supply voltage 5 amp constant current limit. but I've set my uh load to constant current at only 4 amps. so it'll be booting into constant voltage mode and not into constant current mode. So let's capture it on the scope here and see what happens.

Switch on. Bang transient. That's not that great. Look at the overshoot there.

There's a little bit of Step there. then it ramps up pretty linearly, but it goes up to 4 Vols that's a that's not great at all I Don't like that overshoot. That's pretty terrible. Make sure that wasn't a fluke.

No totally repeatable performance. Hey, this thing's no good at all for powering Well I wouldn't like to power a you know, a large 3.3 Vol uh board because that thing's going to overshoot to 4 volts. Nasty. Let's try the same thing again.

but this time I've changed my constant current load to an amp. so bang hey there we go. It's a different different performance again, but it really hasn't essentially overshot this time. But it's got this nasty little down.

The the switch on performance isn't great there at all. I'm not not very happy with that. Let's do that again. to totally repeatable, it looks like same performance again at 5 Vol at 4 amps I Dro my current down to 1 amp and let's try it again.

Bang! that's at 1 amp. Switch on performance for 1 amp load. but check this out. 20 volts Now 1 amp bang.

The switch on performance for one amp is quite there we go. That's not bad and if I just uh, switch my load to constant power I've got 10 wats constant power so it's giving us 10 volts at 1 amp 10 wat. So this is the transit switch on performance for 10 wats constant power. Let's go into 10 volts constant current mode and let's do it again.

And that's our switch on performance for constant 1 amp constant current mode again, 10 wats. and what if we've got no load at all? Well, let's give that a try. Here we go bang and that's with no load zip so but there's no overshoot. No problems at all.

but let's wind this down to and let's try No load at 3 volts bang There We go. no overshoot. a few little step responses there and let's see what happens if I switch my constant current load on and see how quickly uh, this uh display current display ramps on and stabilizes it pretty much jumps in there. It gives you a slightly lower reading one into H it jumps pretty much straight to it.

so there you go. It's a little bit out. um, you know, but we're only talking like 25 20 milliamps out at the full 5 volts. That's u under a percent.

No problems at all. Uhoh folks, something's gone horribly wrong. Something's gone horribly wrong. It's showing 36 Vols on the output here, but its output's actually 423 volts.

I was mucking around with the con constant resistance uh mode on my power supply and I I had it set to 1 ohm um I think yeah it was yeah I got got it set to 1 ohm there constant resistance and I was uh McKing around with that and uh, 6.5 amps. We're all over the shop here so it's not going constant so much for the constant current mode W Something's something's gone horribly horribly wrong here I Don't like this at all and it's stuck on 36 volts output. I've managed to cause it to go into some ridiculous mode where it's gone massively. No, it's jumping all over the shop and the display lay is not updating at all.

That's constant resistance mode. We're getting five six amps out of this thing. over current protection, over voltage protection on. Oh, it's going haywire and really, there's no excuse for this I mean it's showing 12 volts at the moment? That's just nutso and just will not switch that output on.

And but it's actually outputting 17.6 volts even though it's only displaying 12. And here's my fluke here. and trust me, that's there. it is.

It's 17.6 volts. This load ain't line well I Think the only way I'm going to be able to fix this is to actually, uh, repow the thing, reset it, which is crazy I Don't know, we've got our output. There we go. We got our output.

It's back again, But something something's going on here. Damn it. I Don't like it at all. No, it's like right.

Set it for 6 volts and it's 17.6 volts. What? You got to be kidding me? Something's something's going wrong here. 12.2 volts. What do we get? and we're still getting 17.6 volts? Let's switch it off and back on 6 volts.

Uhoh folks. I Think we've killed it I Think we've killed the supply. Do you believe it? Wow. Output: 7 points.

Okay, so it's Re. You know it's set in to six volts and it's it's Once you switch the output on, of course it goes to what you're actually displaying. Um, and it is. Actually, it's now displaying correctly the output voltage.

But it's crazy. It's set to six volts Fail. Got to be kidding me. Unbelievable wo and now it's gone off the deep end.

We're talking 50 6, 6.5 Vols It's like if I switch that load on if I like if I go back to say constant current and let's set it to a uh, very basic 1 amp here and uh, we've gone in constant current mode. It's saying it's it's outputting 50 volts at 1 amps. it's only it's peaked. it's you know it's gone Max and that is that is a real voltage.

Look, let me let me probe this. This load ain't lying. There is 50 volts on that output that is nuts. Well, it's more than gone off the deep end.

I've got this. the output switched off and it's still giving me 14 volts at 1 amp output. the output is Switched Off Damn it. Look, it doesn't even switch the output voltage off anymore.

You've got to be kidding me. It switches the mode. but it doesn't It's continuous output. Well, what can I say? That's the end of the bloody review.

I'm not even going to bother going any further I've killed it. The Eev blog review curse strikes again. Now this is unbelievable. The fact that I've done something to it I'm going to have to open it up have a look at it, but it's just it's completely died and not just like not giving any output.

it's giving output over and above what you set it. even when you turn the thing off. It's ridiculous. and it doesn't matter what I do with this load here.

I Can short this thing out until the cows come home. A good power supply. You shouldn't be able to kill it. It's ridiculous.

Go. not if it's just going to die when I'm just playing around with an electronic load like this. It should be able to survive Dead shorts on the output cuz that's what all the current, limiting and everything's for. Unbelievable loser.

I'll keep you, uh, up to date with what happens with this thing. Maybe we'll try and investigate it somehow, but hey, sorry. Charles I killed your power supply. You want it back.