Hi Welcome to the Eev blog an Electronics Engineering video blog of interest to anyone involved in electronics design. I'm your host Dave Jones Hi It's product review time again and it might actually be considered a bit of a secondhand, almost retro product review. What is it? It's the Hulet Packard / Agilant E 3610a bench Power Supply. Let's take a look at it now.

I Said it was retro because this one is actually branded Huet Packard comes from the Huet Packard days The model's been around for all. the series of these bench power supplies has been around for a long time and I believe you can still actually buy it under the Agilant name and it comes in several different types. This is the single output uh type as we'll take a look at, but it's also available in a dual and I believe a triple output as well and you can usually find quite a few of these on eBay. Now if if you're after quite a, you know, if you're after a top quality bench power supply for your lab, it's pretty darn hard to beat.

Hulet Packard Agilant supplies. They make some of the best bench power supplies in the business. They're not cheap, but as I said, you can pick them up on eBay for reasonable amounts of money. Now this one I've actually got here is the 110 volt version designed for the US market and other markets that use 110.

Vols. But of course here in Australia we're 240 Vols Now uh, unfortunately there is with these series HP supplies. There is no switch on the back to actually switch through to. uh, you know, make it switchable from 110 to 240 Vols So uh, unfortunately, I'm going to have to crack this open and see and that's what this uh blog's really going to be about.

It's not so much a review of this, it's going to be uh to see if I can, uh, modify this at all? Well, easily. Anyway, to do 240 volt operation here in Australia cuz hopefully inside there'll be like a little jumper switch or there'll be a on the main board, there'll be a Transformer tap or something like that that I can just easily swap over to 240 here's hoping. but let's crack it open and find out and just before we take it apart I thought I'd power it up cuz I do have 110 volt transformer here in the lab. so I thought I'd power it up and it seems to work just fine and as you can see, I've set it to 10.0 volts and we're getting 10.02 and we wind it down and we, uh, you know, 2.19 2.20 it's pretty darn close and uh, if we use the constant Uh current, we switch it around here to amps and we plug it in and it's currently set to Uh 0.25 amps for constant current and there it is, 252 milliamp so it seems to work just fine.

And just a few tips if you're after a really good bench power supply like this: Uh I hope Highly recommend one that's got a low voltage range. This one's actually got two ranges they call it 2 amps and 3 amps here and it's got a real meaty push button switch on there. none of that soft button rubbish. and uh, this one has a nice low voltage range of 0 to 8 Vols uh at 0 to 3 amps and 0 to 15 volts at 0 to 2 amps.

So uh, what that allows is you know if you get one of those uh, cheap JC Car power supplies or something. the most common ones are like 0 to 30 Vols and really, they're not much. you know they're just a too wide range for General Electronics uses or there's very few reasons you need to go above 15 volts. So a 0 to 15 volt Supply is a beauty and it's got constant current uh mode as well.

So it's got current adjust and voltage adjust and this one actually allows you to actually set the current here so you hold in the button and you can set the current without having to short out the output which is the traditional way that you set uh, the constant current limit on a power supply. so it's nice if it has a constant current set button as well. Uh, but one of the most important things people uh often. uh Miss on a good lab bench Supply is it Must have a nice multi-turn pot.

Now this these H Packa ones have a nice 10 turn pot and as you can see, I can just tweak that and I can really finely tweak I can just touch the knob and I can tweak that down to 10 10 m resolution. No problems at all. Now if you got one of those cheap uh bench power supplies with just the Uh voltage and the current like it'll just have like a coar and maybe a fine voltage current adjustment, they're only single turn pots and they're no good. You can't get the resolution you need on that and this has a 10 turn pot for the current set as well.

So beautiful! And those pots are are quite expensive so a lot of power supplies you'll actually um, you can pay extra to get the 10-term pots. It's well worth it. I Highly recommend it. and also it's got an earth output as well.

this one's fully floating. Um, it's nice if you get the dual one with the negative rail as well. but this is a single output so it'll do it. it'll it'll do uh, the General job and if you got a second one, it's a single output.

because they're floating outputs, you can. they're not Main's Earth connected unless you link these two together the ground and the Main's Earth then you can actually join power supplies in uh in series to get um that positive and negative Supply So if you only got a single output Supply Like this, it it doesn't matter. Get a second. Supply Bingo You've got a positive and negative one.

and the best bench power supplies you can get like this one are the are a linear Supply They're not a switch mode Supply so that gives you much better noise and ripple performance on the output that you really just are very hard press to match with a switch mode power supply, but because it's linear, it needs a big heat sink on the back. It is a bit wasteful in terms of um, energy consumption for a given output power. but H Who cares about that? Noise and ripple is uh much better now. I've got a couple of switch mode lab supplies up here I've got this: Powertech Big 40 Amp uh one here, which is to get that in a linear Supply 40 amp output up to 15 volts.

that's you know, quite a beefy linear. Supply So it's not a bad option for a switch mode and this one up here is a an Electronics uh kit as well. and it's a switch mode Supply as well. but its uh, noise and performance figures aren't nearly as good as a good quality.

uh, linear bench Supply like this huet Packard One and the linear ones are far more reliable as well. Now, as nice as this power supply is, it's not per it's not the perfect bench Supply Because the perfect bench Supply would have an output load switch here to switch the output off and on, but unfortunately these series of hulet pack up ones don't have that capability. Now the interesting thing to note about the construction of this thing is that it doesn't have any screws on it at all. It's got these little uh tabs here like this that you can see so it looks like these, uh, it looks like the back panel at least uh, flips off and maybe the front panel as well cuz there's a couple of tabs down there so let's give that a go, shall we? Yep, there we go.

that's it. Smaller screwdrivers to go there and bingo that just pops off and it looks like there are no extra uh screws on there so it looks like I think that top cover is just going to pop? Yeah, the top cover pops off. so I've got to pop off. Looks like I got to pop off the front panel as well.

so let's give that to go. Oh yep, yep. all right. Ho there we go and Tada too easy.

Wow, it just pops off and let's see if we can get this lid off Taada There it is Beautiful! I Love it and that was very nice indeed. I Love how it just popped off and this uh, front panel just hinges on the wires here which we'll take a look at. but there's the big uh Transformer As you expecting any linear Supply there's the output transistors there. They're a 2N 605, 5 6 made in Mexico in a T3 package just hooked onto the heat sink here, some lovely uh, grounding wires just going over there and uh, the board looks very nice indeed.

As you can see, there's the main uh filter cap and you'll notice that they've got the uh. They've got the celastic rubber goo there on the cap and it's also on this side here as well. and that's a nice little touch to ensure that that Capac C doesn't vibrate and uh, and fall off and cause damage. So they've got some more of that on the cap over here.

so nice little attention to detail there. A couple of smaller heat sinks. um, pretty standard. Um, it's a very sparse uh layout.

some of the Um standard opamps there I recognize that's an LF Uh, 442 lm393 LF 411 So pretty basic stuff really, but that's what it you expect in these standard linear supplies. There's nothing fancy at all. and they've got some nice 10 turn pots in here too there, obviously to, uh, tweak and adjust the output range. and as you can see, the front panel here just sort of hinges off like that.

and it's really, uh, really is quite nice. There's those. There are those uh, lovely 10 turn pots. They're actually uh Burns ones.

so they're super high quality, but you know you'd expect that cuz you pay top dollar for a HP uh HP lab supply. So you'd expect top quality 10 turn pots that'll last you a live time. Pretty much. it's uh, there's another HP branded uh board in here and it's got some.

um, they they look like little Custom Custom devices I'm not sure. um I'll have to have a look at those, but they're obviously just driving the display. They're the analog. They're probably like an analog to digital converter and then uh and then a display driver as well.

There's another couple of 10 turn pots up there for adjustment, but I like it. Nice little cable looms and it's just quite nice. Construction: beautiful and interestingly, it looks like there's nothing holding this board in at all. Tada There it is.

Look at that. It just comes out as one complete unit. Beautiful! Now as for modifying this for 240 volt operation: I Don't see any internal jumpers on the board at all to actually do that. or uh Taps on the Transformer that are easily accessible cuz here's the input uh Mains wiing and it goes all the way down to a real main switch on the front and then back and then it looks like straight into the Transformer there.

So unfortunately I can't access the bottom side of that Transformer there because uh, it's looks like it's not trivial to take this thing out because if you look down in there you will see, uh, where is it You will see that the output Taps on the Transformer are soldered directly onto the board down there. so I could undo these four screws here. But uh, really, the Transformer is um, still permanently attached via those direct solder connections. So it looks like I'm going to have to actually take off this back panel here and to do that, I'm going to have to take off these To3 transistors I'll have to unscrew unsold of those from the board to get at the Transformer What a bummer bit.

Oh well, let's do it. So there you have it. We got the heat sink out and I'm massively disappointed. Look, the wiring goes directly into the Transformer.

There are no uh, solder tabs on that at all. There are no Taps so that I can change it to 240. Vols So ah, what were HP thinking when they did this? Uh, they obviously use a different transformer for each market. They could have just had one with Taps Surely.

Well, there you go. That's a real bummer. I was hoping there'd be a Transformer tap in there that I could switch it to 240 Vol So, but no, it looks like they use a totally different Transformer that's why it's got uh standard stamped on it because uh on the actual Transformer itself cuz this is the standard model I think it's option like 03 or something if you want the 240 volt model. So just be aware of that when you're shopping around on eBay or something trying to buy these babies.

they're a really nice Supply I Highly recommend you pick one up if they're at an affordable uh price, but unfortunately doesn't have a load switch on it. But hey, that's not a killer. You can't beat a quality HP lab supply on your bench? Go for it. And because I don't remind people of this very often.

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