Hi welcome to Mailbag Monday Everyone's favorite segment and yes, this one is actually released on a Monday or at least Sydney time. so no complaining that it's Sunday or whatever where you are s Monday here in Sydney Geez. Anyway, look, we're overflowing again with mailbag items, so thank you for everyone who send them in. I won't be able to get through them all I got like five uh postcards as well or something.

so let's get right into it. Oh by the way, um, everyone liked this background thing and me opening them on camera I got almost zero people who said uh, well, like one or two one I think who said that? they uh, preferred the older format. so hey, I'm going to stick with this new format. Let's go Okay first package comes from Frankie Tong and some people may be familiar with Frankie he is I love Electronics on the Forum But not only that, he is also the guy who uh uh, sourced and supplied these beautiful goldplated binding post I use on the microcurrent.

and he's got an ebay store and he sells a whole bunch of uh uh stuff and supports it on the Forum. So check out I'll put in a link to Frankie's eBay store down below so check it out if you're uh after cheap um, parts and meters and all sorts of stuff from direct from Hong Kong Frank is your man and also I've had a lot of people complain during the mailbag segment about the knife I use to open my packag and how wimpy it is. Well this is the Victorinox mini champ. It's my everyday carry knife I Love it.

It's tiny compact, it's got everything in there I need uh, on an everyday basis? fits in the pocket really well. but I agree. Okay, fine, that's not a knife, that's a knife. Yeah, let's open Frankie's package, shall we? No problem whatsoever.

Works like a dream. All right, let's go. What's Frankie sent? Woohoo! It's a multimeter and here I was thinking he'd sent me a new multim meter cuz he does sell uh new multimeters Briman and uh, Unity and other brands as well. But no, he sent me a vintage one.

awesome and I thought you'd send a Chinese made DMM I've I've done several ex Soviet Dmms yeah I don't think I've ever uh, torn down a vintage Chinese multimeter so let's take a look. It's the Brri uh, seal he bought it uh New Old Stock Beijing radio Research Institute which doesn't exist anymore. All right, and it's apparently very fluk like. Woohoo! let's have a look.

Thanks! Frankie And of course it's the A model. Couldn't afford to reprint the Box Oh goodness, let's check this out. Manual operating manual. It's hey.

there you go, it's not in Chinese look at that Wow. specs. Ah yeah. half a percent.

just pretty crusty uh stuff. just your typical uh 3 and 1 half digit. DMM By the looks of it, let's check it out. Oh yes, it is very fluke like it's got the old fluke um.

side style buttons. a classic and wow, what the hell? Probes: are they not shrouded? Got some weird ass two-part molding thing on there and these are just just weird. Where's the finger guard? It's like slide off. Oh man, they.

they're just weird. So yeah. classic. Uh.

Side switch: Arrangement Uh. cloning the fluke 80 20 of course, and other models. So what's coupling? I Don't know what that is. That's rather weird.

It's on the AC mode, so is that like an output function and they uh uh. by output I mean um, that's the old analog multimeter term for having an AC coupled input. Um, but you sort of do that and it disconnects it I Don't know. Continuity Tester: Not a latching one, but yeah.

pretty quick, instantaneous, and of course, a crap transistor tester. It's the Hallmark a cheap ass multimeter. Oh I Hate that function. And one of the problems with the transistor tester.

look. Exposed metal? Uh. pins here. You got to wonder.

are they connected to the? Are they isolated from the inputs here? Probably not, so you could easily hold in this thing, have your fingers on there and maybe be probing something. I Don't know, maybe not. But anyway, it's in theory possible you got exposed metal there, so fail. Yep, look at that.

You got like 10 o between Common and the emitter for the Npn up here and it's just. you know. it's just not great. I mean there goes all your uh, um, your various uh safety ratings that not that this thing would have any uh, you basically wouldn't be able to get a safety rating with a transistor tester on it these days, but hey, it's not entirely crap.

I mean I've seen a lot worse and that um LCD by the way is uh, very big, clear and it's got good angle on it and it you know it feels okay. so on the outside it's it's not that bad. I don't know what uh vintage it is. we'll find out when we open it.

I Guess All right here we go lift the lid. hey look at that two. Ball construction. it's got shield in.

Kind of surprised at that and uh, there you go. look at that hand taped uh board artwork. Of course. There you have it.

That's basically uh, you know what you expected from. maybe you know, an 80s vintage, uh meter or something like that. Um, if we can get a look at a day code on that eight pin dip there, then we might be in luck. Uh, check that out.

that's really interesting. It's got a, you know it's not bad I Don't mind at all the Um angled support there for keeping that LCD at a specific angle and they've socketed the uh chip on the back, it's just going to be a, you know, an inter cell uh chipset. um single chipset like that. Just that's a bit how you're doing, uh, just wiring that stuff over there like that.

But you know, I mean everything. Basically all the multimeter functionality is on pretty much on the Uh on the top board there and the rest of it is just sort of, uh, all your input circuitry and uh, miscellaneous. There we go. That's a T62 dual opamp there and it's just got 948 and what's that? EB So that's not quite a date code.

That's not your typical four-digit date code. Unfortunately, let's try the LCD Uh chip or the main multimeter chip. Aha, no surprises ICL 7106 Yep, that was the chip used in every 3 and 1 half digit multimeter on the planet around that age. But look at this.

this is a '90s vintage there. There we go. the 20th week 1990 that was still manufacturing this thing. Jeez, that's yeah.

I You know this has all the feel of like, well it was definitely a design and sold in the80s that's for sure. And there you go, that's quite nice. The PCB designer was thinking, look, they actually uh, made this as a panel like that and you can see the uh breakout tabs there and there on the top of the board and they manufactured that as a panel. Very nice indeed and then it just flips up like that.

Shame It's you know, they didn't use like a nice tidy ribbon cable on there or something like that. but uh, what else have we got there? We got a Uh 40, 30, 4,000 series Seos, and an opamp and basically not much else. What's that? That's probably the external no your midle base collector. There you go.

So that's a transistor and um, well, that's all she wrote. That's all that's in a 3 and 1 half digit multimeter of these uh era. and of course the ganged Um switches. they actually look and feel quite okay I don't mind that at all.

So this isn't too bad for the era you not going to get all the requisite input protection you get these days cuz the standards are much higher. Um, there's our 10 amp. Is it 10 amps current shunt? Yeah. 10 amp current shunt there.

little bit crusty. they've just uh, trimmed it there to Value but yeah, I expect it a lot worse. That's actually not that bad I guess. and that's an interesting mounting arrangement for the P transducer there.

If you got the board area, it's not a bad way to do it. actually a big cut out on the bottom and then uh, just a couple of tabs on the side to solder on directly to there and then just wire off a single wire. It's better. I Think that's better and more elegant than having your traditional uh, two wires.

You know, just coming off like this and flapping out in the breeze and wired through to your back panel. Of course, it's not as good as mounting it on the back panel having the Springs come up. um, things like that. but if you're going to wire it to the board or have it permanently mounted to the board, that's not a bad way to do it.

And a couple of trimmers down in there. There we go. and they've put some, uh, sealant on those. So yeah, somebody's uh, got themselves at the right tongue angle there and tweak those.

So yeah, it's only a typical you know, half% meter. so nothing Flash and you can forget any HRC fuses just then M205 glass type there. So as I said, doesn't really meet today's safety standards. We' got input, uh, protection resistors, but that's about as far as it goes.

There's no Ms or uh, Ptcs. Now that's into interesting. look at that. They just taped over sort of like five individual traces over to there instead of doing it in one big fat Trace Why sort of, you know, staggered fusing capability or something like that.

This is for the current shunt resistors. So yeah, that's unusual and somebody's had a hack at that one. There we go. That's an aftermarket mod.

There's actually a piggybacked resistor on another resistor, so they couldn't even be bothered to suck it out. They just sold it it straight on top and there it is, just bodged in down there. how you doing so that does kind of suck I guess but well I've seen a lot worse. thanks Frankie Very interesting.

Next cab off the rank addressed to that crazy Aussie bloke um with from no name so heck let's check it out. All right, let's go look at that just slices straight through Beauty And we have a book. We have a book here we go. Amazon 10 Essential Skills for Electrical Engineers I was uh teed up about this one I uh had forgotten about that.

Let's check it out o How to design circuits looks pretty good. Let's go. and if it's got a Swiss army knife on the front, you know I'm going to like it but hey, is that a Winger or is that a Victorinox H um and it's got a choke look at that good on your Barry L door with two RS Um, it's part of the I E press done by Wy and uh, let's take a squiz. Well let's go the blur on the back.

In today's competitive Marketplace Engineering students and professionals need every advantage to succeed in job interviews and in the industry. This insightful book will serve as a valuable reference for them throughout the interview process and while on the job. Interesting. Okay, um, 10 Essential Skills applies the fundamentals learning school to the Practical tasks required by employers.

Awesome with the ultimate goal of helping readers land a job and succeed at it. Excellent, uh, insightful chapters that teach them how to design resistive circuits, prevent thermal fires Awesome Analyze circuits. use stats uh to design manufacturable products. Design feedback Control Systems Op Amps all that sort of jazz? Yes, all this sort of essential stuff.

Um. and I hope he's left the math out of this Anyway, is a PR um Barry is a principal design engineer at Dayron World Communications Here's to Circuit analysis at San Diego State University Servo Systems for the I and numerous industrial seminars. Holds eight patents, but I won't hold that against you and Bazer as I'll call him is from Uh Kbad in California I've been to Kbad hi to all my viewers from Kbad and there he is good on your Barry Legend and uh, about the reviewers of the book. John Berardi there you go and Joshua Joshua door.

let's zoom out a bit. uh Bruno pad if I'm pronouncing it correctly. Notes to instructors and we're straight in like Flynn How to design resistive circuits. Here we go oh yeah, th and sources all the good stuff.

Design of a decoupling circuit. Yeah, we're straight into it. Look at this decoupling into opamps and biasing design of pie attenuators. Oh I won't show you the whole book.

Oh, then you won't want to buy it. Oh, How to prevent a power transistor from overheating. Chapter 2: Beauty All Right starts out with a thermal model here and then goes straight into and I like this part actually using manufacturers data for thermal analysis and then it shows you typical data sheet figures and then how to design thermal stuff. Oh, and there's the heat sinks wonderful and then how to analyze a circuit.

We've got ourselves some mat lab code for you fans out there. Oh, and it just gets better. How to use statistics to ensure a manufacturable design awesome, and how to procure a custom component and then goes into all the manufacturing stuff on that and the bell curves and everything else. H This is really good.

The chapters are only uh, short in these things, but they seem to be to the point and have some nice info. Not an absolutely Complete Book I Don't think, but geez, there's some handy stuff in here. a second order control system design. Oh, it's getting meaty and it's got opamp, noise stuff and uh, all sorts of things.

Yeah, lots of traps for young players. Capactive loading looks good, but once again, a pretty short chapter. but uh yeah, there's some useful stuff. And the Final Chapter getting your job, keeping your job and enjoying your job.

Beauty So Bazer says that this book is, uh, for graduates and people going for their first job or for seasoned people who just want to refresher on what he thinks are the basic topics that you might typically encounter in your first year on the job designing Electronics systems or you might get at job interviews and things like that. So he selected uh, his things. basic resistive circuits uh basic. Um, how like stuff overheating power transistors? things like power? uh, thermal Stuff How to analyze circuits, transfer functions and statistics is a big one.

Totally agree. Uh. feedback control systems excellent basic opamp stuff analog filters you got to do how to design digital filters, how to work with RS signals and uh, enjoying and keeping your job. So it's a fairly eclectic, uh mix of things, but one ones that uh Baser personally thinks are the go and well I don't disagree at all.

This looks like an excellent book I recommend it. So thank you very much Bazer, that one's a ripper. I'll include a link down below to the Amazon store where you can buy it I think it's about 40 bucks or something like that. Um, but a bloody Amazon the Kindle version is only like a couple of bucks cheaper.

You kidding me? Anyway, good on your bazer. Next up, we got one from an Aussie Scotty Brown good a Scotty he's a Queenslander. Bloody Queenslanders. We beat you this year, by the way.

Absolutely thrashed your ass New South Wales did. Anyway, let's check this sucker out. I'm really liking this sucker. This is a Bobby Dazzler.

It really is. Look at this and it can even, uh, slice bananas as well. bloody Ripper M Jeez, that was a good banana. let's have a look at Scotty CIS Woo, What is that? It's like a transistor radio.

Awesome. Pure evoke flow. No, it's got like a LCD and stuff on it. Fancy pancy.

um and uh. let's read the note. hi Dave This radio was given to me by a friend with a busted LCD It supposedly has already been repair once but failed again. Looking at the specs online supposed to do both digital and Wi-Fi internet radio.

Aha! I Thought you might look at it for a tear down or fix to add some tunes to the lab. Awesome cool, Thank you very much. Well it actually looks pretty Jazzy and it's got some uh 10 term knobs here. I've uh, powered it up and we do have a uh, it's got a well, no, it's gone in standby and uh, it's uh designed.

um in the UK manufactured in China but um, it's this snooze handle. Okay, ah, okay, so right. Got it There it is. Look, snooze handle so you can just touch that.

So obviously it's a capacitive um touch uh sensor so you can just hit the snooze handle like that. It's got an alarm on it, but that is pretty good. I've wanted a one of these Wi-Fi radios for the lab actually I don't have one, but uh, shame the LCD doesn't work. Maybe we can fix it.

let's do a quick tear down. there it is. It's got an aerial Beauty and uh, looks like it has room for a uh battery pack. Yeah, it's obviously like a Lithium.

probably a Lithium rechargeable pack or something like that. and you requisite uh, stuff there and a a ported enclosure here and well. well, yeah, few screws on the back. Let's go.

All right. let's see if we can use the antenna there to there we go. Hey, look at that. Hey, some decent shielding on that.

Look at that tape around there and all that, uh, all that shielding that's actually quite, uh, quite substantial. And they've got. Look at the foil shielding they've got on the on the ribbon there going to the capacitive, uh, touch, front panel and ribbon going over to the LCD. Yeah, it looks like somebody's had a hack on that.

LCD So now, is it just me or is there something wrong with that? Uh, Power Amp there. it's just not sitting quite flush with, uh, that heat sink on the back of it. Not that great. and yeah, well.

yeah, you're going to need a lot of thermal paste in there to compensate for that and it's going to be pretty poor. Jeez, that's not great. This PCB is from imagination Technologies Pure digital Um, 2004 Is it is that? 2008 I can't see on the screen 2008 There we go. I Need a higher resolution screen I Am getting a higher resolution uh camera? It should be like in the post today.

I'm getting the new Canon Hfg30 By the way, I'm shooting this with a Hfg10. so I'm upgrading to a new model missing not function there. but yeah, this is like a digital, uh, digital receiver. and WiFi um thing.

I'm not going to obviously go in and this is not a full tear down. so I'm not going to go in there and desolder all those cans and stuff like that. but uh, yeah, I do like the shielding. plus they've added a Ferite on there as well.

Beauty And there's your Wi-Fi antenna that's going to be, uh, reasonably effective. There's not much to Wi-Fi antennas really. and uh, they're rather interesting. uh, theory on um, how they work.

They've sort, of, you know, anchored it right up here. sort of put it away from the metal work heat sink so that should perform fairly well. Nice. um, you know, fairly thick.

MDF case on the thing. pretty good, and there's a little PCB going up to your snooze handle there. There you go. Why just running off? So yeah, it's just a capacitive touch thing.

and check out that LCD board. Somebody's really had a good hack and slash along here. what the hell's going on down there? and they've taped it all down. So yeah, no wonder I mean I'm not sure what's failed, that's it.

Looks like a little daughter driver board mounted onto the main board for valy shaft encoder mod. PCB Pure digital, blah blah blah okay, well ad these are the uh, by the way, the main board is the rotary uh encoder. hence the yeah, there it is V Vdi shaft encoder PCB And then they've got this uh little LCD uh driver board on top and yeah, I Jeez, your money's got to be on that connector. Oh yeah, look at that.

Somebody solded and repaired that flat Flex connector. Oh goodness. So there's nothing you know. nothing's blowing.

The LCD probably isn't blowing, but something's gone wrong with that flat flexes, which is really unusual. Um, it's almost as if like it's been cut or something like that. I'm not sure, but jeez. I don't know.

Anyway, we have a part number there with the uh RIT display. Maybe we can just buy a new one instead of dick it around patch cing that. so thanks Scotty I'm actually going to um I'm very interested to actually try and fix this thing cuz I think I can make good use of this sucker. So yeah, I'm going to have a shot at that.

Maybe I'll do that as a separate video. And the really good thing about a battery compartment like this fully, uh, sealed effectively, is it's a good place to put your screws when you've uh, got a work in progress. Beauty And next up, we got one from Christopher Silx If I'm pronouncing that one correctly, he's from duth um in the United States of America So let's crack this one open and uh, see what we have inside here. Is that going to do the business? Maybe not.

No. Oh look at this man. hang on. How of these boxes open? Pain in the ass.

should just sliced the whole damn thing there. There we go. All right here we go. We have: Tada it's a HP Jet Direct card.

Awesome! I Needed one of these for my uh, dumpster dive printer which I got. So um, thank you very much I'm going to whack that in. It's a um, uh, 10100 ethernet uh card basically and it just slips right in the back of the printer. Beauty I needed that sucker so thank you very much.

And Chris has also included in the note. Tada 10 bucks. Awesome. None of that us Funny Money business.

This is a genuine Aussie polymer note Beauty Awesome! Thank you very much. I'll uh um, get something saving nice with that. And next up, we have a pretty big post pack here from Uh Stefan Key Booms Jeez, why can't everyone just be Called Bruce Anyway, for those who know your money, python um he's from Poway in California USA so thank you very much. All it says is really old electronics.

Oh we love really old electronics. Can you smell it through the pack? Nah. Anyway, let's whip this sucker open. Oh shouldn't have done that.

Should have known it's that horrible bloody cushioned. Oh hang on. No yeah, fail. Pull tab to open.

Unbelievable. Anyway, let's have a look here inside a FedEx package. So oh, they're just. they're evil.

Stuff's everywhere. Anyway, really old electronics. Woo! What is that? Oh wow. Memory board.

Yes, it's a memory module I Whopping 400 words SL bytes of memory. It's a Ferite core memory presumably for a Semon's main frame manufactured in 1970 was still in Diapers at the time. Wow, thank you very much Stefan Let's take a look. Wow! that is fascinating.

A big plastic enclosure like that with a uh couple of jeal row uh uh, you know. back plane connector to plug into the system. Surprised it doesn't have like a handle on the thing actually to move it in and out and it's doublesided. Yes.

Oh look at the density. uh presumably 200 words per side. So 100 words, 200 words, 300 words and 400 words fite core memory. and yes, there it is.

Look 30th of the Eth 1970 goodness. Now if you don't know how these magnetic core or Ferite core memories um actually work I'll get the macro lens out and try and get a real closeup on these. I'll link in the Wikipedia down the page. um down below.

It's quite comprehensive so I won't go through a huge amount of uh detail on it. but uh, suffice it to say that each there's a little Ferite ring on each one of those bits and each Ferite ring is W It's all W woven through with all these wires and they can store an individual bit, a one, or a zero in each one of those little ferites in there. So there's like thousands of ferites in this thing. Fantastic.

All woven with the wise as we'll see when we get the macro lens close up. But the thing about these is that, uh, when you read out the data, you would actually destroy the data. Go figure. it's actually destructive memory.

Unbelievable. Anyway, let's take a closeup look at the little ferite rings in there and there we go. Check that out. You can see these tiny little ferite cores and all woven in this intricate minks.

I Would love to see a video of them assembling these. I Think there is an old video like it's part of uh, you know one of the NASA Um, you know the Apollo computers or something wind in these memories and the elaborate machines that actually do it and uh, I'll have to dig that one out. Somebody will link it in, no doubt. But there you go.

Each one of those little ferite rings can store one bit of information and if you read out the data, you destroy it. Unbelievable. And I think that's a 4x4 arrangement in a coincident weave as a coincident weave current Arrangement as they call it or something like that. And to store each bit, they put a little pulse through and you can magnetize each individual uh Ferite bit.

Awesome. And they basically be an XY grid on this thing. uh, as you'd expect and also a third sense line and an inhibit line as well. Um, and you would, uh, put a pulse on the XY lines and you would either get or not get a uh value out of the sense line depending on whether it was a one or a zero.

But as I said, actually putting that pulse in was actually could actually be destructive to the bit itself. And I bet you it's next to impossible to get data on what that these devices are for. the rows and columns. Oh, not a chance.

and just look at the Crusty flux residue on this. You would think that this thing's being reworked or something, but no, that's the factory soldering. Oh goodness. All right, I'm on my Tano microscope here, so let's have a look at this puppy.

We can zoom in on this and uh, get a pretty good look at this Ferite core memory. look at that. That's as close as I can get. but there you go.

you can see that there's four wires traveling through each one. so these are all enamel coated wires of course and the green one. there is going to be the sense wire and uh you see how they just all Loop through and wound around and yeah it's all bit how you're doing but uh it's quite an effort to get these through cuz these are absolutely tiny these things. and um so green one is your sense wire and then uh then you've got your X and your Y wire running through and then the fourth one is going to be your inhibit line.

So there you go. That is a nice little closeup of some magnetic core memory. Love it and we'll consum Zoom right back out on that and can see how they just all wide through in that Arrangement So jeez, just imagine doing that. They got to have some sort of automated way to do it.

and then of course then you've got these lines actually going through I can touch those. Look at that. and uh, that is just beautiful thing of beauty. It really is.

and that is a 100 uh words of memory. I Think however big a word there is I Don't know Somebody want to count it? Go for it. And just as a very quick comparison between old and new, look at this 1970 magnetic Core memory technology we're looking at about. you know about a 100 bits stored in that in those magnetic Ferite Rings There's about 100 of them fit in the same space as a modern micro SD card.

Look at that. This one's only a poultry 2 GB um card. but we're talking aund just even if it's 2 GB we're talking 160 million times The amount of information? Unbelievable. So basically what you'd have is just your X and your Y drivers here and a Sense line going through there.

and then you would apply a current pulse to whichever location you actually wanted to on this thing. and then you could sense the data back on the Sense line and you can set or set a one or a zero in each one of those little Ferite. Rings Absolutely fascinating. and uh, the access.

uh, speed or something like this around about a microc or something like that. So basically 1 mahz ramw looking at here, probably maybe a bit slower, maybe a bit faster? we're not sure. so thank you very much. Stefan I've always actually wanted one of these for the lab I should like frame it or something like that cuz it is fantastic.

but before before I do that. um I will. probably. uh if I get time, do a video on this actually powering up this and actually Rite in data to it and see, Well, it should still work.

It's just a bit of Ferite and some wires. um, you know I have no idea about these driver chips over here, but we can easily just tap in I mean easily. just wire in and bypass those and we probably should be able to store some data in here. Um, so if you got any good ideas for uh, doing that, please leave it in the comments.

So thank you very much. Stefan And that's probably all for today's mailbag. Not a huge number of items. I Still got a whole bunch left, but this has probably gone long enough anyway.

and well don't want to blow all my mailbag. what in one? Go catch you next time.