Hi for many, many years now. I can't remember how long. I've kind of had this idea that I would actually like a bench multimeter that's battery-powered and I know there's You know, there's quite a few around and this is actually one of them. I've had this down in the storage bunker for quite a long time.

You can't buy this anymore. It's a Gdm 80, 41 Gw Instinct. It's not a particularly good, uh bench meter. It's You know, I don't know how many counts it is.

It's like it doesn't really matter. Anyway, it's a bench meter that has, uh, like one of these, you know, storage, uh, things in it for your, uh, test leads. So it's like a combination of a portable meter. You can't actually use it from a 9-volt battery.

It's actually got a 9-volt battery snap. and I'm powering that from a 9-volt external supply at the moment. Or you can power it from a mains input as a bench supply. and there's You know, quite a lot of meters on the market like this over the years.

The first, I believe, please correct me in the comments down below if I'm wrong, is One of my favorite looking meters of all time is the Fluke 37. And here's a photo of it. It's a portable multimeter and it's a similar sort of thing to this. It's powered from a a nine volt battery.

Uh, it doesn't have mains input. it's actually battery powered only. and it comes with like a little probe storage box. I just really like the look of this meter.

It's sort of. And it's got an angled face on it, but you know, like it doesn't have features. It was just designed along with like the 70 uh, see the original 70 series uh meters back in the day so you know it doesn't really contain any. uh, great functionality.

But the good thing about this is it. Just like I just like the form factor of it and I like the fact that it's battery powered and this actually has a thousand hours, uh, battery life. I'm not sure how much this Gw instax one uh has. We're actually going to measure uh this now and they're like, yeah, I've got bench meters, right? There's a couple of bench meters yeah down in there.

Okay, and they're absolutely fantastic bench meters. But look at all the crap I got on my bench, right? This is all mains powered. I don't want another damn mains powered thing on my bench. I've always kind of like had this little obsession with a battery powered bench meter.

So this video is, um, just going to be a first investigation into Um and just like thoughts, really, it's just a, you know, like a Thoughts video. Is there a decent bench meter on the market that can be converted into a battery-powered meter? And when I'm talking battery power, I don't want a thousand hours, right? The yeah, The Fluke 37 Fantastic thousand hour battery. What life? One of the longest ones on the market. The famous Fluke 27 which I've done a video on.

I'll have to link that in. It's also got I believe a thousand hour, uh, battery life? I'd like. You know, let's go for ten thousand hours. Can we actually, uh, mod a a current bench meter on the market? That's actually a rather decent uh bench meter even if it's one of the cheap one hung low brands and things like that.

As long as it's you know it's half reason. What's got a good set of features and things like that, and it's You know its performance isn't too bad. Can we actually convert it into a like 10 000 plus hour bench multimeter? I just why I don't know, don't ask me, I just i I just love something like that. So anyway, obviously, uh, like it's going to be possible with this.

I don't know. like is this thing going to take like five milliamps or something like that? Obviously, uh, this project, um, it. You can rule out any uh bench multimeter with the vacuum fluorescent disc display. It's got to be something like this that you know uses your traditional uh like multimeter chipset designed for handheld so they've got you know you're gonna get like at least you know, 300, 500 hours? uh, something like that.

but it's just in a bench uh form factor like this which makes it more usable. So yeah, the only way you're going to get the low power is to have an Lcd and off the shoulder chips. Oh geez, that was loud. Make me jump.

I have no idea. Um, what's inside this. I've never, uh, taken it apart to my knowledge. Anyway, I probably did, but I I forget anyway.

Um, it's got big shielding on the back. Um, two big fuses. Even for the uh, milliamp, I've got a big ass fuse. It's missing.

I've obviously salvaged those over the years. And this one, uh, he's got a broken, um, ground jack in. it's broken right down the bottom there, so I don't know how that happened. But anyway, um, yeah.

obviously even if this takes like five or ten milliamps, look at all the room you've got in here. I mean, you could just shove batteries in there until the cows come home and you can get your 10 000 hour battery life. Um, but you know. Anyway, we wanted to look in.

uh, types of batteries measure the current consumption. Look at the types of batteries available for something like this, possibly. And no, I don't want any of that lithium ion lithium polymer rechargeable rubbish. No lithium primary cells.

I want something that I can just whack the batteries in this thing and leave it for a decade or more. 10, 15, even 20 years, and it's still working right? Of course, there's you know famous stories about uh, fluke multimeters on their original battery. you know, and things like that, because you know It's hardly ever using, it'll go into low power mode and things like that. So if you've got something with like 10 000 hours battery life, that's just a nice round number I'd like to I shoot for because it's an order of magnitude better than anything else on the market, then you're talking over a year of like continuous operation 24 7, but of course a meter.

This one will, uh, I'm sure it'll go into like power down and things like that and you can simply turn it off where it draws nothing. So you know, like 10 000 hours battery life should. Just like, you can store Lithium primary batteries in it. You never have to change them again for like, probably the next, like 15 20 years, something like that.

So anyway, let's measure this bad boy. Okay, this one's actually interesting in that it's um, as I said, like it has a nine volt battery snap and the battery is supposed to design. Uh, going there. I think I've got, uh, maybe there's a well.

There was a holder for it somewhere. anyway, uh, designed to hold a 9 volt battery and that goes into our little board down here. if we have a look, it's actually got a 7812 12 volt linear reg here, obviously. Uh, the ac coming here goes into from the transformer goes into the bridge.

Rectify here. Here's the main uh fielder cap for that and it's got two diodes in the back. There one's a, um, yeah, like a current steering. uh, does it come from uh, the nine volt battery snap here or does it come from the mains and it's like you know either or uh thing and uh, obviously this.

I don't know. This thing's not going to be power from 12 volts so I'm pretty sure it's going to have a uh, another regulator. And sure enough, a little itty bitty regulator there that looks like it goes to the positive lead and negative lead down here. Which parrot.

So what is this actually powered from Because that determines what type of battery? Uh, we're going to be able to use. Hey, Three Three Volts. Spot on Three Volts. That's interesting.

Um, and that because I was thinking about this three volts. I think it's going to lend itself very nicely to a certain type of battery. a Lithium Thional chloride battery and we'll take a look at the data sheet for that in a minute. I think we could be on a winner here.

If this is like just fixed 3 volts input, then sure, you can power it from like, you know, lithium double A's and stuff like that. But oh yeah, what happens when it goes under three volts? Yeah, I don't care where wouldn't because the lithium, uh, Thionyl chloride batteries, uh, which I'll explain in a minute and show you have an interesting characteristic curve and they're designed for ultra long life like this sort of application that we're after, so that is going to work out well. I think we can power it from a single cell. Hmm.

now we need to know the battery current. so we'll just break into that. And because it's a linear regulator, almost all of the current goes like straight through. so there's like only like, you know, tint, like tens of microamps or something in the control pin of that, uh, micro.

So all of the current flows uh through into the meter. so it doesn't matter what voltage you power it from. Um, it's going to draw. Look at this.

1.75 milliamps or negative. All the electrons are going to fall out there. We go. 1.75 Milliamps New Bm 786 available on the Ev block store by the way.

Yep, oh, one and a half Diode E mode capacitor mode. Looks like it's 1.5 milliamps for everything. It hurts in Adp and Milliamps. Oh yeah.

okay. 1.8 and 1.8 no workers. Everything's under 2 milliamps. Very nice.

Oh yeah, this thing has a backlight. so you know, like turn on the backlight, but it doesn't matter. You're not going to use that. although.

yeah. 36 milliamps. Okay, so you need a bit of pulse capability. uh there.

but you know any battery solution for this is easily going to handle it. You know, something like a pulse current like, uh, 36 milliamps for a backlight? So wow. Like that's like worst case? Um, of course, it could draw more. Uh, you know, a few milliamps more depending when you're in Ohms range, for example.

but you know it's neither here nor there. Yeah, worst case: 1.8 milliamps? Wow. that's nice. Under 2 milliamps? Beautiful.

That's sniff of an oily rag stuff. So at, let's say, one and a half milliamps here. If you used, uh, one of those newfangled, uh, lithium, uh, nine volt batteries in this thing, they're about in the order of like 1200 milliamp hours. So at 1.5 milliamps, you're talking 800 hours here.

So this is actually this particular model. Pretty darn decent if you're whacking a Lithium 9 volt battery. you get a few hundred hours less than that if you whack in an alkaline. But yeah.

nice. Anyway, as I said, this meter been discontinued for Donkey's years. Um, it's not even a consideration I've seen, but there are other similar sort of ones on the market. And uh, and that's all I need people to find in the comments down below.

I need to find a potential suitable candidate for this. Anyway, let's go to the videotape and take a look at a battery solution for this. Oh, all right, there you go. There's a quick squeeze there.

Um, curiously, it's got something just fell off. Um, it's got a hybrid resistor divider. Nice. Um, yeah, I wasn't expecting that, but I think from memory this is like a point.

one percent like class meter or something like that. So yeah, that's understandable and it's You know, it cost a pretty penny. I think. There we go for those playing along at home, I can't actually see a chipset yet.

If you switch aficionados. there you go. And interestingly, it's got bottom contacts down there as you saw and top contacts. Wow.

Looks a bit like we have a date code 99. Um, yeah, it doesn't surprise me as 20 years old. Uh, well. I'm glad I opened this because this is a first I think.

Correct me if I'm wrong. I've never seen a Jrc That's got to be Japan Radio Corp. Uh. Chipset? Um, is that uh, is that the part number and that's not the date? Um, Nju92 10 The chipset.

Can't say I've ever seen it. No Jrc? really? All right. What I think is a great, uh, battery choice for an application like this: When you're looking 10 or potentially 20-year battery life, you don't want to be using your regular Alkyl lines. You don't want to be using your Lithium ions or your lithium polymers.

I don't want any of that rechargeable rubbish. anyway. Um, you're looking at a Lithium primary solution. And of course you can use the Uh.

9 Volt batteries. And like the 9 Volt and double A's and other ones you can get from Energizer and other brands that are Lithium primary cells and they're pretty good. We'll take a look at those in a minute, but what we want to specifically look at here is what's called a Lithium Thional chloride battery and here we go: Rsr components. You can get them in different site, you know you can get them in regular double A batteries C They don't carry a D, but I'll show you a D data sheet in half Double A You can get ones with tabs that you can solder into your product and things like this.

And they specifically have Target 10 to 20 plus year applications and I've used these in underwater applications, military applications. uh, commercially. Where these things like these products, you need to, you know, design and test them, get them ready, all set up, and they need to like sit somewhere for like potentially 10 years before they're actually deployed or used. and then they need to perform.

Um, so yeah, these lit. That's what these Lithium primary batteries uh, can do. And these are really cool. These aren't high energy.

this particular chemistry is not high energy, but it's designed for low power stuff. Exactly what we're looking at. Well, uh, compare the uh, Lithium um, primary, 9 volt and double H. And how I know how I mentioned before, I have 1200 milliamp hours for a 9 volt Lithium primary cell that you can just you know, buy in the shop as opposed to Alkaline.

typically 800 milliamp hours. And here we go. Here's a discharge curve of a leading brand name competitor: Alkaline. Uh, like this in the purple but the uh, this is an ultra life Uh brand.

This is their white paper. the chemistry conundrum. Um, comparing Alkaline or uh, Lithium 9 volt Discharge curve here. much much better.

So yeah, 50 more energy. And of course if the energy is the area under the curve here. So if you calculate do the integral of the area under the curve you'll find yeah it's 50 more energy. So yeah they're really cool.

But these are actually though these Energizer and other brand Double A and 9 Volt Lithium primaries are not this Lithium Thional Chloride battery chemistry. It's a different type. These ones. Let's take a look at the data sheet.

Here it is. This is a Saft Uh brand. Once after one of the you know major manufacturers of Lithium primary cells like this. High energy density 3.6 volts.

Remember, we're looking at 3 volts before Double A sized Bobbin Cell. It's just a double A battery. But here it is ideally suited for long term applications, typically from 5 to 20 plus years Featuring low base currents and periodic pulses, these are not designed for high power applications. You have to go to a different Lithium chemistry if you want like really high Pol peak pulse currents, and higher you know, operating currents, high power uh devices and stuff like that.

These are designed for really low power base currents and then you know just the occasional little pulse and things like that. So great for um yeah, down here grown internet of things Of course I mentioned in other things you know, perfect utility, meeting, tracker and tracking systems, alarms and securities. You know if you've got one of those motion sensors up in the corner of your uh room? for example, one of those wireless ones, it might have a long-term Lithium primary battery like this one in here and it just draws you know Nafl current, little pulse occasionally when it transmits and you can get you know 10 plus years battery life, out of these things, medical devices, all that sort of stuff. Um, and technically these can leak.

but because they're designed specifically designed for 20 plus year applications, they don't. You have to really abuse them or something for that to happen. I've never heard of actually one of these leaking. So yeah, it's just not a thing.

This is what you want for a low power, long life battery application. So yeah, nominal capacity 2.6 amp hours. So 2600 milliamp hours and they're 3.6 volts nominal. But let's take a look at oh, 9.36 watt hours for those playing along at home because you always have to specify battery capacity in what hours And in milliamp hours, that's just Bs.

Got to be what hours. So yeah, anyway, any time somebody or some you know some company gives you a battery capacity energy capacity in milliamp hours, just slap them over the head. Anyway, let's take a look at the discharge curve because this is really interesting. We don't want the voltage plateau versus current and temperature.

This is what we're looking at. Look at this curve. Isn't this the stuff of wet dreams? Look at this. Look at this brick wall response just drops off.

and what are we operating at? You know, like two milliamps, right? So we're looking at the the red curve. Look at. Look at. look at the red curve.

Look at it. It goes for like 3.6 volts. It might drop down to 3.5 until it just suddenly dies right at the end. And that's the discharge capacity in milliamp hours.

So it's got at least 2500 milliamp hours. So um, because. well, I can talk milliamp hours now because I'm not talking about energy anymore. So let's get our confuser out: 2600 milliamp hours divided by what was it? 1.5 milliamps, 1700 hours for a double A.

We could if we stuck one lousy lithium uh, Thionyl Chloride double a battery into this thing. Um, it'd work for 1700 hours. Beautiful. That doesn't get us to our 10 000.

So let's up our game. Here we go look at this bad boy d cell. Oh yeah, you can even get them bigger than this too. But this is like a standard D cell and you get them with tabs and everything.

17 amp hours and it's going to have the same characteristic. Drop off. Here it is. Oh, this one only gives you ohms oh no.

Hang on. Yeah, that only gives you homes. Oh, that's disappointing. Anyway, it's going to be the same thing.

So we're you know, somewhere just below somewhere between there. So we're right up in this region. Here's probably do 17. let's just be generous and call it 16.

16 000 divided by 1.5 milliamps. Winner Winner chicken dinner 10 000. Oh, it's backwards. You're going because I've flipped Dave Head.

Sorry, Dave Head has flipped so my eyes look in the right direction when I'm doing this. So all we're gonna do is whack this one D cell in there and we've got our ten 000 hour requirement. Isn't that fantastic? But because like this is not a candidate meter, what I want is for people to try and find a suitable bench meter that has a suitable feature set. I mean, you know I would love if they released re-released 97 and I did a twitter poll on this.

Here it is: if Fluke Corp made the Fluke 37 again, would anyone buy it? Um, stupid Twitter because it doesn't allow images in polls. Anyway, here's the poll. Oh, it's neck and neck. but 50 percent of people say they would buy one.

Um, I actually forgot to include. I wouldn't say re-release the Flukes 37 as is like make it like you know, 60 000 count or something like that. but don't have anything fancy in it like you know. Just like okay a bench meter like this I would have like maybe serial out so that will take more current.

Of course if you've got like a serial output maybe it'll have a bluetooth grown something like that just for Pc connection optional. You can disable it if you want to change battery life. but I just like the simplicity of this. Just look at it, look at it.

It's gorgeous and thank you very much Anna Crow Computers blog because this is a gorgeous photo. I just I just like the simplicity of this. I like the slope face and you know it's just got minimal buttons and like a big display. Of course you want a nice big readable display that goes above and below because you might have it down on the bench and you might like have it angled up or something like that so you might be looking down onto the screen like that.

so you want you know a lot of Lcds will die. They'll optimize for straight on or down below like that. So you want a fairly wide angle like that because if it's up on top of the bench you want to be looking up and if you when it's down on the bench you want to be looking down. So anyway yeah I just I just love the look of that like it's even got a little stand and everything.

It's just it's brilliant. Anyway, something like this, I'm thinking maybe you know, like sixty thousand count? Even a six thousand count is, uh, good enough for Australia, Good enough for daily use, right? So like sixty thousand count. Obviously they have modern functions like capacitance and have, yeah, well, this one's got min max and real. And you know visual continuity and all sorts of, you know, nice sort of modern kind of features like that.

But yeah, what do you think? Who's with me? Who's with me on trying to find a suitable candidate bench multimeter and just like designing a battery solution internal that lasts for like 10 000 plus hours? It's not hard because there's going to be a ton of room inside these things. so you know, like we could go to like a hundred thousand hours or something insane like that, right? It's It's just not hard. So there's just tons of like, oh, here's an old Rs1 that looks very similar, but there's just tons of bench meters available. There you go.

Um, who makes that? Um, who's the uh, who's the Oem for that Once again, you know it's just got the batter, the storage compartment for the leads and things like that. I have no doubt you know you'd easily convert that over to ten thousand One. It's just a matter of finding like a suitable one so that this might have come out of the same. I don't know if Gw Instinct actually designed the one that we're looking at or whether or not they did that, but obviously you know we can't We can rule out anything with vacuum fluorescent displays and things like that unfortunately.

So yeah, it's it's just it's not gonna work. So we want like an Lcd one, even like even a cheap ass Victor or something like that. If it's got the features and like it's yeah. I mean there's the Rygole one, but like this is like a five and a half digit one.

this is a series bitter kit. I'm sure that's not going to operate from a couple of milliamps. You want something that just uses, you know, a a chipset, Uni T make one true Rms uh one that's got a nice big display. I've used one of those.

I'm not sure if it's that model, but I didn't really like it. But anyway. um like there's lots of little uh no name. You know there's ones from Banggood.

There's an aim to aim Tti. They make good stuff. Well, they want to for 996 bucks. Um, once again, that's a five and a half digit uh.

charging. Oh there you go. That's got charging built in. Oh it's got Lan and Rs-232 It's going to be.

No, it's going to be too high a power. It looks like it does have a battery solution, but it's not. It's not for the uh you know 10 000 plus hour that I'm after, but that that looks like a nice bit of kit. Anyway, I'm sure there's no shortage of candidate bench multimeters out there if there's not one.

Um, there's an old Gw instinct that's got. I've got the lead version of that one. uh, lead display. This one's got an Lcd version that's probably rare as hens teeth.

What is this? No namer. Never seen that before, but uh yeah it's You know it's got like similar display. Are they still all using the same display anyway? leave your thoughts and comments down below. Do you want? do you want Flute to bring back the Fluke 37? Like an upgraded? Call it the 37b or something and just you know, have a bunch of extra features.

I just like the sexy look of that case. Whoa. Can't get enough. Oh, that one's a bit crusty.

Got a label on top. It's got a carry handle on the side too. and oh good stuff. So anyway, am I the only one who wants this crazy thing like a 10 000 plus hour bench multimeter that's not powered from the mains? Maybe I'm the only one? I don't care.

I'm going to find one. I'm gonna make my own comment down below. Catch you next time you.