Hi welcome to Teardown! Tuesday We're going to take a look at an interesting power supply today. It's from a company called Power Designs Inc in New York And it's a precision power source. It's a Model 2005 and just as the name suggests, it is a precision power supply and you can tell. Just look at these funky dials here with a nice precision vernier feeling that is just unbelievable.

And that's got a hundred micro volts, adjust range, by the way, and you can basically just dial in the voltage you want here. Five Point Zero, Zero, Zero? Yes. and then you can adjust it by I'm not sure if it's plus minus hundred micro volts or plus minus fifty volts, but 50 micro volts. but yeah, a real precision power supply.

And it's incredibly. It's not just precise in terms of actual precision. When you talk about a precision power supply, it basically means it's stable. hence the light up here for the oven on the thing.

Yes, it's got an oven stabilized Xena reference in it, and that's why the stability is point Double-o one percent plus 100 micro volts over an eight-hour period. or basically one micro volt per week. Or better than that. So it's a really nice stable supply and low noise and ripple to less than 100 micro volts peak-to-peak Now, the vintage of this thing? Hold on to your hat.

1964. That's what's on the schematic that I've got. I Don't suspect this one was manufactured then. I'm not sure we won't know until we take it apart, and maybe we might be able to get a date code out of it.

I Don't know. Maybe not though, because there's no like you know, I season this thing that's all transistorized. Yes, it's a solid-state precision power source and these are actually quite popular on eBay and I Believe there's a like a a bigger forum eevblog forum a thread on them and people love these sort of things and it really is actually quite nice with it. You know to dial in the voltage like that is just beautiful.

And basically we've got oven light. that's the up thermostat light and that log meter really understates the precision of this thing because once you actually calibrate it, there's a calibration or input on the back that you can you know, a little multi turn pod on the back. you calibrate it. but once it's calibrated and the ovens on and it's stable and everything else, then you know the precision is quite remarkable on this thing.

So yeah, I mean we've got switchable volts. current metering. We've got a short in switch on the front which allows you to set the current limit. that's only a single turn pot, but that actually feels really quite nice.

And but the big feature of this of course is the voltage. you can just dial it in. look at that, you can dial it into 1 millivolt. and then as I said, a hundred micro volts adjustment.

Beyond that. So it's very nice. and it's got a range doubler on it. You can actually normally it's from 0 to 10 volts, 0 to 500 milliamps, but you can switch it to 10 to 20 volts and that just this light here that comes on adds 10 volts onto whatever.

So if we had five Point Zero Zero Zero dialed in, that would be 15 volts. And on the back panel here you can see that our calibration trim pot there. Yeah, you don't want to go around with that. There's no date code on the back, unfortunately.

I've just got modeled 2005 serial number is Six Zero, Two, One Nine zero. and by the way, if you are going to buy these on eBay just beware. they are a fixed hundred and ten volt unit. So I've if I want to run it here I've got to run it from a conversion transformer I Don't believe there's any internal I switch to convert it over to what 240 and it's got both an AC law in fuse and a DC fuse on the output of the transformer on the thing.

so a bit of extra protection. There remote voltage sense in here very nicely, so just start strapped across in place. But of course, with the precision power supply like this, you want to actually be able to sense the voltage right at your load. And that's what these sense terminals are I mean there's no point having a nice precise 5.000 volts on the output ear power supply.

If then you're going to drop some voltage over a couple of you know, feeder cable go into your product under test. So you know, a precision power supply pretty essential to of these sense terminals on them. Alright, let's crack this thing open and it's gonna be very, very old-school in here. of course.

I Mean we're talking mid 60s? The schematic actually shows it was revised around nineteen. Sixty Seven, Ninety Seven, Sixty Seven, G's hadn't even landed on the moon then. Unbelievable. But you know this thing could still hold its own today.

And by the way, this one does work. But it's not inspect like it's not even close like a dial in 5.00 and I'm getting there like five Point three, four, something like that. Let's take a look. Woohoo! Oh yeah.

First thing, look at this very nice impression under the case by the way. and then a To3 package inside of there and that's an RCA brand RC 1700. Oh, never heard of it before, but it's a big chunky old-school PNP Power transistor in To3 package. Nice! And we can refer to the schematic here.

Look at this 1964 Can you believe it? Wow And they're all linked in this: PDF for this was some scanned in I Found it on Paul Rico's website and he's the one who scanned it in, so thank you very much. Paul And there's the pass-transistor They're classic Darlington configuration. Of course you need the Darlington to get the extra game because you're only using a crappy bipolar transistor with really low gain there. So you really need to have that Darlington configuration to get the performance of the thing.

And so. well. nothing special, but all the power has been dissipated in that RC 1700 on and on the side of the case. There, You can basically see that there's not a huge amount in this, nor that, nor would you expect there to be really.

it's just your basic linear supply. But look at all these precision resistors over here with all your dials and then you've got your calibration and vernier trimmer. Just, you've got your thermostat here. So everything inside that line there is organized.

so you've got your heater up here and thermostat control and then yet. look, we've got a current mirror there and one of those will be our Zener reference down in there buried. But the interesting thing to note about this power supply is that it doesn't sort of make sense at first glance. and the reason for that is because the negative is up here.

Here's the negative: terminal up the top and the positive is down the bottom. So basically everything is flipped around so pretty much you have to turn it upside down to get a more like conventional configuration on this thing. and then it makes a bit more sense. So yeah, they've drawn it a bit weird I don't know.

So when it's upside down like that, you can see that. Basically the positive output here goes basically directly over here through to the transformer. So all of Uri your regulation your pass element is done on your negative output here. and here it is.

There's your pass element down there, so it's all done on the low side, not your more traditional high side. but really, that's neither here nor there whether you use that high side or low side pretty much. But basically the way they're getting the really low noise here. Basic NPN pass element.

Which basically means it's going to be super super stable regardless of capacitive load or anything else. and it's just a nice stable configuration to use, so it's not particularly efficient are doing it that way. But the saw benefit is that it is ridiculously stable. So that's how they can get the confidence in this thing.

the low noise, the ultra stability, everything else. But in terms of absolute reference stability, of course, that's all determined by your oven eyes. dart reference Oscillator Here, these days, you wouldn't need an urbanized oscillator. You can get a precision you know, reference solid state reference source.

You know of any buried, a zener reference or whatever. and you know Bob's your uncle Too Easy. But back then, yeah, it's working in an oven. now.

if you take a look inside this thing. I mean crazy old school construction here. Look at all the loomed war and look like loomed every like centimeter or two. Absolutely brilliant with why is branching out at the exact point that they need to branch out at? Oh, it's a thing of beauty.

It really is. And yeah, this biggest nice red can here is our oven. amplifier oven. stable.

It's a reference amplifier oven and it's got its own that particular part name. and yeah, all your circuitry is built into there. plus your heater. your heater had probably be at the bottom I would guess I'm not gonna destructively tear down that sucker.

It's just not worth it. This thing is interesting. At first glance, it looks like a pot. You know, a big old-school pot, but what the hell's are doing mounted on this tag board? Well, not tag board, but a sort of actually.

I Don't even offhand. I Don't even know the name for these boards with the eyelets in them like that? I mean it's a yeah? I Don't know. Please, somebody jump in. Somebody older than I am with a really big gray beard I Sprayed capacitors.

We'll take a look at those. but yeah, that almost looks like a pot with its three terminals down in there. and I'm not sure what that thing's doing at all. I Have to cross check on the schematic and sure enough I found it.

It's actually our 12 down in here, so it is actually a trimmer on the board so there's no access on the outside of the case so that must have been trimmed with the bottom of the Cape. Presumably you can just take the bottom of the case off, otherwise they would have had to trim that before they installed the board. And of course yes, I was right. Four screws on the bottom tada, lift it off and bingo we're in like Flynn And that's just more beautiful than looking in the topside.

So I was a bit ugly actually. but this is beautiful. Look at these upside down metal cane transistors here and point-to-point to these standoffs that you know. eyelets on the other side that have a component leads going through them.

So this is basically a double side mount board. Beautiful! Look at. this. transistor over here has its own little heatsink on it.

Nice little Finn heatsink. Here's our oven reference. they've got a cap bodged onto that a little Larten in there and Bingo! Here is our trim pot. There we go.

accessible from the bottom side of the board. so maybe I cannot trim that thing back into spec. Hmm. And here we go.

Let's give this a I've got it set to five point Zero, Zero, zero volts and as you can see, five Point One, Six two. so the trimmer on the back side here I can adjust that and basically we're getting ya a very small adjustment range with the trimmer on the back so I'll put that in about the middle and up. Sorry, could you see that? No, probably not. and then we'll have a trim of this one.

I Haven't actually given this a go? Here we go. Yeah, that's feeling. V I Know it doesn't quite go all the way down, doesn't quite go all the way down. Let me try the backside again.

No. I don't think no. that's as no. Unfortunately, that's as low as we're gonna get it.

We're out of spec, so yeah, well. this won't be a troubleshooting reak. Our video is just hoping that we might be able to do that. Uh huh.

What's this trimmer here? Nothing precision like this one. This one's nice. wire. Huge wire, round pot and it just feels beautiful.

When you turn these wire, we're on pots, you can just feel the wiper scraping over the wires. Oh Lovely. No. I Just checked out the schematic.

This pot down here is our 27 over here I Love, sorry, our 27 over here I Love this diagram. It's just beautiful. It really is our 27 as part of the current sense circuit there. so no.

I'm afraid there's something else. By the way, when you're testing any gear, especially really old gear like this, just be aware of any any corrosion inside the contacts of these things. though it can be a bit. Dicky You've really got to make sure you get it right and stable before you start trimming these things.

But you really can like dial this up. Just one there. There we go. Another digit I mean you know it's pretty close.

So and then you can go the next digit. up. Two, three, four, five. you know.

So it's all working. hunky-dory It's just a little bit out of cow. that's all. Bomber I Can't pull it back in with the standard controls and this main sprog field.

a cap here. Check this out. Really old school, but do we have ourselves a date code? look 65 52 on the outer plastic shield and on the inner Can 65 43 So when we could be talking 1965 whoa and some more Sprite capacitors. They're really old-school look.

You can tell Hundred MFD and that is Micro Farad's yes, they didn't use them. You know the Muse symbol back then? it was yeah. MF d MF Microfarad and you'll notice this in the datasheet as well. For the thing, you'll see the specs like the stability stick.

Miss BEC For example is you know, point double O One percent plus plus 100 MV And that's not millivolts. it's actually microwave volts. So yeah, that's just old school talk. Check out some of that switch mechanism in there.

I Mean you know, jeez, you'd wanna if you're going to do these, you'd want to go in there and get some contact cleaner. I Don't think you know I've rotated and you want to rotate these things a whole bunch of time as well as well as using some contact cleaner on the things. But yeah, that's not my problem here. I've already I haven't cleaned them, but I've already rotated them and stuff like that.

so obviously there's something else wrong that doesn't allow me to trim it within range. Oh my God. ourselves. A combination of precision resistors in here plus plus your more common just out your regular run-of-the-mill our carbon ones where you know tempo and precision isn't critical.

Check out those tiny little diodes in there. They're probably like little point-contact germanium Zoar something like that. and just because I can on my new Canon HF G30 camcorder. that's which has twice as in my other one with my time ten macro lens.

there we go. Oh that's fun! Woohoo! Look at that. Beautiful, although not exactly the best subject, really. a old-school big wire.

you know, point-to-point wide device like this thing. Not exactly a great test for my new camera and macro capability. but just take a look at how that wires just you know, nicely wrapped through there properly and then soldered. Probably really knew how to.

you know wire stuff back then. And the wiring looms? I mean look at that. Just beautiful. but I Just find it really fascinating.

Like the double-sided board construction there with these eyelets and the point-to-point wiring on the bottom. and it just yeah. it really brings back old school memories that's for sure. And yeah, this was, you know, pretty bit of a state of the art power supply back in the mid-60s that's for sure.

Anyway, that's just a brief look inside this Power Designs 2.5 precision power source and it really is very nice. There's now currently right we can set it. look at that. There we go.

turn it in. it seems to be working, but yeah, just slightly out of spec, which is a little bit of a bummer. You'll see that oven light actually you switch off there at some point when it cycles through the thermostat light. But yeah, I just love these things.

It's just very nice. It just oozes precision. the front panel. it's just beautiful.

That was a very quick teardown. and by the way with my new ya Canon a camera here. it's actually showing the total time elapsed since I started shooting. I've shot 24 minutes and 28 29 30 seconds worth of footage.

so that's enough. I mean I think don't want to tear it down any further. There's nothing interesting, but I might do a follow-up video with this if people are interested in trying to bring the thing back into spec. So I hope you like that little teardown.

Tuesday's for some vintage stuff I mean this is before even I was born and I'm pretty old so there you go. If you liked it, please give it a big thumbs up and as always we want to discuss it. Yup! the A/v blog for my AV Book.com Catch you next time you.