Hi welcome to everyone's favorite segment: Mailbag: Monday where I open my mail Yes I've said before. Oh, definitely say it again. it's gotten out of control. There's no less than 35 packages here I think I may have even miscounted there.

my yeah, one or two more than that I can't count that high. Geez, So thank you everyone who's sent in this stuff and sorry if I don't get around to opening your stuff I Definitely won't get around to opening most of them on today's mail bag, but let's give it a try, shall we? Got the trusty knife and well I don't know I might start with some swag. Yes, we have some swag not electronics related as such. it comes from my Atlassian and the software and other eye geeks.

computer geeks will know who Les Ian is I won't pretend that I know everything they do. they do I collaborative software tools among all sorts of other things. my good mate Roach work say you've seen on the blog before G'day Raj And they have sent me some swag and it is. Check it out.

Check it out. look at that angry nerds. love it with yeah let's symbol on the back. There we go! Awesome! Thanks guys! Oh linking it Atlassian down below if you haven't heard of them mixed up one completely at random from Germany Yes I Got a ton of German viewers Hideaway German viewers yet again, there's almost I Think has there been a mailbag without a German something from Germany I Doubt it.

Anyway, this one comes from Christian finger I Won't make any jokes there. Okay, thank you very much Christian and he's from Who'd if I'm pronouncing that correctly Huda in Deutschland So thank you very much I It's got a description on the outside I Won't tell you what it is. It's not hugely descriptive, but here we go. Oh it's got little little foam.

Look at these little fine pellets. Haven't seen any that small in a long time. so let's oh yeah, they're going everywhere. They like them then like bean bag beans from a bean bag.

if you ever accidentally spilt bean bag beans. oh my god they're hard. Anyway, um ignore Royal finger instruct the mission I it's a CD I I guess I Have no idea I have no idea what my Go Royal There you go I have no idea I'll have to play that or I am assuming no it's a DVD So what? I'm gonna do fingers welt who are fingers? Well I look like happy chappies. There you go and let's have a look.

I've got some green felt stuff that's just I think it's just fuel haul I do love and it starts getting everywhere I Do love like Oh Awesome three-in-one little tractor Lego Thank you very much Christian that's awesome. Um of course that's um for Sagan and daddy as well. Daddy loves beanbag little pellet beanbag beans there they clump together due to study by I Think it's some static? That's a cause he knows to hit me. bounce around.

it's quite fun. Too much fun to see. Yeah yeah, yeah, it's gonna be a mess. It's gonna be a mess spot.

Let's have a look what in here but Cynthia says it's an old measuring instrument. That's all I Know and oh, we love analog meters here on the Eevblog and check it out early. Philips unit. look at that.

haven't opened to Philips Analog meter before. Awesome! Thanks Christian This is a very bland looking meter. Analog Meter: I Must say it's just so like. you know, no edges around here.

It's all just sort of. you know, exposed. very sort of basic, sort of low-end type. our construction not super rugged.

Now one of the most interesting things about this is check out this one. Micro amp Full scale. How can it possibly do that? Well, it can't because it's not a traditional analog multimeter. This is the dead giveaway electronic.

The only way you can get one. My camp full scale deflection is to have an electronic or often called a FET Vom or FET Volt Ohm meter FET meter. whatever you want to call it. Yes, it's got a FET amplifier input stage to allow it to measure small currents like that.

and it's quite unusual in that there's no terminals on the front. Where are they? Where are the banana jacks? Well, they're on the side here look and just labeled on the top. It's a really quite a piss-poor design from that aspect, There's how Ohms are just on the side. I Don't mind that and we've got ourselves a little positive in Venegas Evite and indicator over here and just your usual wire ganged switches here with an off button because if you leave this thing on, it's a fit Vom and it'll draw power.

So there we go. It's got some nice instructions on the back like that and this one's actually made in Holland So that's kind of like a no. I Don't think they actually use Holland anymore. A lot of people think Holland is what's now known as the Netherlands but Holland was only a small region of the Netherlands and I Sure, which part but a a small region of it.

but I think people are a bit forgiving if they refer to if you refer to like Holland and the Netherlands as Holland. Anyway, here we go. That's a rather neat instructions there. Battery check, how to do all your adjustments and calibration.

Excellent. And there we go: The two kilovolts, input protection, and the frequency range. 25 kilohertz? Yes, Huge frequency range. Um, typical accuracy? Yeah, Three percent.

Very typical for an analog meter and two 9-volt batteries. and that's pretty dodgy. Someone's had a hack at that look at the hot snot on the back of the head, so they've clearly replaced those with it. Looks like the battery snaps that they got out of the top of the 9-volt batteries.

because if you're ever short of a 9-volt battery, you can actually take apart a 9-volt battery in. Take the battery snap out of the top there and use it and solder some wires on and well, that's what somebody's done here. I Think which is all fine and dandy except the bloody things don't fit anymore. Don't and check out the fuse there.

just screw in a bit of fuse wire. Oh, that's very how you're doing, but it looks like they give you a spare spool in there so you just unwind it. Good. Okay, fair enough.

That's neat. and it's got a 1.5 volt battery as well. That would be for your higher current hour low Ohms ranges, but generally for just regular measurements, you almost certainly only underneath the two are 9-volt batteries. There we go, can do our battery check and that's just fine.

But one of the most annoying things about these is that look, you got at zero the meter out. No, it's not actually Foley and well, it could be. But in. But in this case, you have to actually zero the thing over here and that's not your regular zero Ohms adjust which used to on an analog meter.

that's a separate control over here for your ions range. This is for your regular measurement ranges. Well, there's no joy measuring a resistance at all. It's Gonski And one of the things you'll notice about fit bombs like this is that the Ohms scale is back to front to a real analog multimeter.

Over here. is it because it's got infinite as full scale there, whereas a real analog meter has zero at full scale. Like that? Big difference, but it is bang-on Four volts. Look at that one volt.

full scale, no worries, and two minutes here. downtime. Check out that a little bit. How you're doing.

it's all over the shop. You can see some flux residue left on the left on the components here looks soldered on the top side like this. They've sort of like done it as a double-sided board. as in like they've got the pads on the top, but there's no traces on the top that I can see.

and they've got wiring running everywhere else. Anyway, we had there's our way ganged switches there and you can see the CV how they're linked together and the big bar in there for the off will actually just switch those off. so it's got its own board. It's really quite weird.

We've got some mushed wiring there and I'm kind of a bunch of resistors there. That's where we've got some like point-to-point wiring down in there. some more, you know, it's just it's all over the shop. and then we've got ourselves some transistors.

They've got little life spaces underneath those and it's just it's really pretty awful. I'm not sure what the hell they were doing there and sort of like, you know, they got little solder points here. This is for the shield on the back there, but yeah, it's like slap together. It really is.

Hmm. impressed by that at all. They look like capacitors that's got a hundred hundred puffs on it. Look at that directly on the input.

Jack's there Wow and we can see that again there. Look at the colour code. old-school There's obviously some current shunt resistors I would be guessing and because this is such a high performance instrument, you got a thermally bond. The two presumably fits down in here.

Look at that. So that's why they got the metal in there to where I keep them at thermal equilibrium to thermally match them. Yeah, that is just horrid. Look at the flux residue left over on that.

Oh my goodness. and this is unlike a Philips uh, you know Philips used to make some really good gear, but apparently not this one. Hmm. Next up one from the old art Elliot veers from England of course it for those who don't know, but the old art is.

um, it is labeled and opened before December oops I'm sorry Elliot let's have a look. squeeze stop three before opening. All right, no worries, look at this. thank you great letter over there we go.

It's a Christmas card. thank you very much. Yes it is. Christmas it's the 18th today so yeah, almost going to call it quits for Christmas Although I work for myself so you know I don't get holidays and apparently Elliot has come up with a website that allows people to log on and then not control Christmas trees that there you go like a you know Christmas and decorations and lights and all that sort of stuff using that X10 Automation module.

So there you go. I'll put in the link down below if play around with Elliot's Christmas lights beauty and apparently this one. He had his hard drive in there which is metal case of course and apparently it arced over to his TV says he, so that's got to be a isolation Foley up primary, secondary isolation. fire in this cheap-ass power supply.

These things. It's a bloody heart and he's also sending one of these I See him: 11 Home automation, you know, wireless receiver thingamabob. So a two minute teardown. So here's Elliot's Cm 11 automated modules here.

they're for another company called let's Automate Dot-com I don't I assume that they are made them and there's the receiver of course. so we can. we can switch power presumably I remotely. and here's our PC interface.

Got a couple of triple-a batteries down there that's got the that's just the serial way USB or USB I think it's a serial adapter and of course one of those weird-ass pommy plugs on it. Got the fuse embedded in there so let's just crack these open very quickly have a look. Wow. I Wasn't expecting that.

Check it out. Old-school so it looks like you know, nineteen seventies, early eighties through-hole stuff. all single sided board and you know we've got our our chokes down in here and just very very old-school Unbelievable. We've got one dip package down there that's got to be our micro or something.

Usually it did giveaway is that they've got a serial number sticker on there, so that's got to be for your serial decoding. but geez, you know, look at that. I believe I Was expecting some sort of surface mount job, not something smack out of the 70s and I was gonna say that's probably a pic down there and sure enough, you may not be able to see. it's very hard to read, very fader, but it's a big sixteen C58 man, old school and down in there we've actually got an Atmel La E Squared prom.

Wow But yeah, I mean the other chip over there is just a opto coupler for the isolation. but Wow and she's a little bit crusty on the bottom there. And of course, look at this nice I Hand taped out and you can see the isolation around here. Lots of flux residue left over from the hand soldering and it looks like we've got just as old school under the receiver here.

and look at that. There's the little selection knobs there so they just select the yeah, the various frequencies or whatever and bingo, We're gonna have a matching pic down in there, no doubt and not a huge amount more. This thing is weird. It's my first guess would have been at some relay for the for the switching, but yeah, it's just very very bizarre.

So yeah, that seems to make sense. We've got of course our our two larger high current why is here which looks like goes then you probably can't see that but looks like there's a big-ass contact down in there and got ourselves two coils here. so that's gotta be a It's almost as if like it's a sort of you know they've customized their own relay. they're you know, cuz there's no branding on it or anything and well look at that.

How old-school is that? Unbelievable and it just latches from side to side like that Wow I mean surely they would have just been able to buy something off the shelf, but maybe they needed the form factor or something perhaps. So yeah, I mean you can buy these off the shelves I Don't know why they why they rolled their own anyway. they must have. Well, I assume that roll their own.

Maybe this is an off-the-shelf one or many manufacturers of these things use them I Don't know, but it's novel. Yes. so the way these work is that you you know apply a pulse to one side of course and you can move the bar across and it just latches in that position and then you can energize the other one or vice versa And then you can latch it in the other position like that so you don't have to keep the coil energized to where. I keep the thing open or closed.

And yep, that one's a pick, but not the same. It's a Pick 16 C-54 this time. So there you go. That was a interesting little mini teardown.

Thanks! Elliot Next up another one from the old Dotard. This one comes from Mark Elliot but look, somebody screwed out his name. But yeah, Mark Elliot from Ah Monmouth Shire in the UK Never heard of it. Okay, thanks Mark.

let's check out what you sent here. Squeeze shall we? Okay, all right people, take their boxes down. No. I'm not gonna use anything more elegant.

Hey got some postcards from Tintern I Haven't been to Tintern along the river? ask whisk and um, some. Hey they got riding on the back. It turns out that's the Monmouth Shire um canal. So there you go.

Very nice. I Like the look at that. He's armored enclosed a calculator. We love calculators here on the eevblog when he started boarding school in 1975.

so we have ourselves and something else as a little tear down. Oh, it's a four banger. It's a four banger Commodore Look at that haha. Classic Commodore Four Bang-up Wow and I Stand corrected.

it's not a four banger. For those who wonder what that term is, it means that four function calculator. It look like A by the number of keys. but it has all the scientific functions so it is a proper scientific calculator.

It's got ever look F1 and F2 so you press F1 and you can get sine and F2 and you can get you know inverse sine and a PP to our conversion. Awesome! And yeah it's yeah. it's a bit inconvenient. just like to get your exponent is just.

you know they're really hopeless. but still it can do it. 1975 Vintage Commodore It's gonna have looks like a red LED display and serial number eight thousand and Sixty six. Not sure what the model number is.

here we go I'm going to power it up and yes it's got one of those red bubble displays in it. and yeah it was this like Commodores first-ever calculator It this may very well of being so today. oh no. kinda sort of works.

Oh there we go. There we go. and well not many digits on it. That's probably gonna leave a couple in there for the exponent.

So if we have to go to the exponent there yeah there we go. we can. yep - three tada and then we can. maybe yo get the get the log of that today.

Oh it takes a bit better. got there and as with all these calculators back in the day, yeah there's nothing to them. Use one of these National Semiconductor I believe are LED bubble displays There, it is. It's still got a whole bunch of those.

Look at that. We got ourselves a Commodore it's a 3 chipset solution there. Wow, that's advanced. Usually only a single chipset solution and well, bugger all.

so that's I presume that's the display driver and this is the calculator engine. Not sure what that puppy there would be, but we're talking 1976. There we go. 23rd Week 76.

They're all. Yep. So Wow yeah, that's just the Commodore custom I think I Guess that's nothing else in a couple of jumpers. Jeez, they couldn't get the single sided layout fail on the single sided layout.

The Holy Grail. Of course the single side layout says to have a zero jumpers, they couldn't get it in. Mark also sent in one of these eight Universal Hvga to HDMI converters ie. you know standard VGA input and up and there's the audio as well.

and you get your HDMI output of course. So yes, supports a reasonable resolutions there. What is the interesting part about this is that I used to work on this stuff back in 1994 a tacky cop and back then it was rocket science to do this. We had a board ten times bigger than this just to do like 640 by 480 Vga to LCD conversion.

Little it like Hdmi wasn't around. then it was just like whatever custom you know interface your VGA had and now Tada look is bugger all in it. A couple of basically two major chips and that's it. There were no chipsets when I was a boy and you know you had to react to implement the thing.

I'm all you so almost of a good lot of it yourself and we had a ton of logic to actually I do it. Lots of programmable logic and other stuff but now it's just yeah. somebody's done it all. Worth it in Nasik Too easy.

But now anyone can buy these chips from digi-key or wherever. Lay out a board in a day. and Bob's your uncle. So yes, we take it for granted these days you can just do this sort of thing.

But 20 years ago, let me tell you, you know, like taking me, taking the VGA input as I said only 640 by 480 and actually recovering the clock on that. and you know, doing the analog to digital conversion and and all the you know the reprocessing of that and outputting it. Jeez, it took a lot of effort and if you didn't get it right, you'd get you know, a jitter on your on, on your ad, on your dot, you know, on your individual pixels and it was. it was.

you know, horrid. I mean we were pushing it to 800 by 600. I think by the time I left there and yeah like it was, you know you have to hold your tongue at the right angle to get the clock right. man.

Open soon. Somewhat time-sensitive hmm not sure that long. I've had this one laying around, but anyway, sorry to what. Peter Marie if I haven't opened it on time, somewhat time-sensitive he's from Niagara Falls on the Canadian side not Canberra so don't mix up Canberra where are our bloody politicians are? Otherwise, it's a nice City Oh yeah visit Canberra what camera? So I don't warm I can't Barron viewers and all my Canadian viewers as well.

So let's see what deaf Peter sent we have ourselves looks like I KITT Let's go and what do you know? Pete's actually a bloody palm here you go I mean that affectionately of course he's that designed an older picket to clone while he's in college and he's also done a power supply and he's got an IndieGoGo campaign as well so we'll check that out. Hopefully we haven't missed it too getting back to college. So he's boards and we've got a couple of crusty old part as well. Hmm.

First up, he's a ceramic hybrid module which Pete's made while it was a back in college and very traditional hybrid arrangement. If you haven't seen these before on the ceramic back I mean there's nothing you know hugely special that requires the ceramic substrate on here. You could have done that on a FFR for of course and just a regular fiberglass our board. But usually with hybrid boards like this you don't use like the regular, you know Oh eight, oh, five or six, oh three components which are Pete's used here.

Usually you'll have those and embedded as part of the substrate hence they named hybrid so there's essentially nothing hybrid about this from that aspect that I can see anyway. I think it's all just regular our service mount components but on a hybrid like a ceramic back in there there. So this is a just a regular I function generator and there's he's a picket to clone. A lot of people did a pic kicked to clone back in the days.

it was quite common but Cheese Pick haven't updated their their pick kit in a long time have they? How many years is it being now? Geez and he's also done a digital art programmable power supply with Jul 12 bit DAC I think he's got here and what is it? Yep, a 13 bit, 13 bit, 8 channel ADC as well for measuring the voltage and current and the pots and all that sort of stuff. FTDI isolated interface and night can bus comms as well so you can daisy chain the boards together and this my power supply was the inspiration. My micro supply which yeah I'll eventually get back to hmm was the inspiration for this so that's awesome. Good to see and I'll link of these in on Peter's website down below if you want to check it out.

and he does have 23 days left on his IndieGoGo campaign to what Raise funds to get him back to college Sophie and help out Pete Please do. There's the link there, but also include it down below as well. And he's also got a an unpronounceable YouTube channel there was you're linking down below. Well, he's got some teardown videos, so check him out! Thanks! Pete We've got some old-school parts as well and these are our Germanium transistors.

And yes, as he says, they are light sensitive so you can actually cut the can off the things and use them as well. rather crude light sensors. So yeah, very common well and they actually do some useful applications for that. and some people do.

they use those in that practical circuits but I'm allowed. look at that made in Great Britain Terrific. Well here's a Pom. Next up, we have a commercial one.

How can I tell? Well, it's FedEx regular regular humans don't generally pay for FedEx it's too expensive companies do because they got me FedEx account or whatever. So um I have some Claudia what's inside this so let's check it out. It's from my aunt Ron services I'm not sure if that's the shipping company all that sleep, how can you make it I can't recall I was clued up on this one. It's been around for a while so my apologies, it's from the local I'm from the suppliers or might be the manufacturers are.

Tech box What is it? It's an EMC probe set. Awesome! and so it is true. So Tech Box so that Antron services that we'll probably the shipping company or something and whoa, look at that isn't that sexy. There we go.

made in Vietnam Well maybe the box is, no it's It's also got made in Vietnam on there as well. So is the probe actually made in Vietnam and I have a postcard greeting days and days from HCMC More pre-compliance accessories to come soon Hein! Thank you very much Hein and let's take a look a wide opening here. let's go open on the other bench. Alright what we have here is the TV Ps1 w AE bla bla bla made in Vietnam but lovely little box it comes in EMC probe set.

There's gonna be yarn near-field probes. Let's have a look. Whoa. look at that.

don't that look beautiful. Oh we've got ourselves our various size near for your probes. they'd be they'd be the H field, they'd be the magnetic ones and it's probably I Assumed that we'd have an e field one as well. they might all be H field.

have to have a look. Anyway, we've got ourselves a little wideband amplifier linear. so basically well. I'll explain and maybe demo this in a minute.

but well, it looks like we got an SMB connector on the end here and we work that over to the RF input and then we hook the RF output of course up to our spectrum analyzer and we can get we can do Emc pre-compliance with this sucker. There we go Got ourselves adapter cable for a spectrum analyzer and a USB cable to pair it and let's have a look. We've also got a manual here near field probes yeah, H and E field. Okay, so yes, the smaller one must be the E field probe because there's two types of measurements you can do with these things: H field which is your magnetic field measurements and a field IVA electric of course.

So you can do your electric field measurements and they're basically two separate tests and the reason you're going to get different sized? I Assume that and these are all your H field ones. The reason you get different sized ones is that you get better coupling with the big ones, but with the smaller loop, that'd be either. So we'd have our loop around there. This one's smaller and this one's smaller.

Again, for the magnetic H field, you can pinpoint more easily exactly where your issue is with the smaller ones. so that's why you get a couple of those. Whereas you don't need that with the e field, just the one will do the trick. So these are designed for M EMC pre-compliance So basically are testing your own product in-house before you go and spend your thousands or ten thousands of dollars to get it actually qualified at a proper EMC test level.

And the interesting thing about these is that not only can you use them to receive pick up magnetic fields an EMC you can use them to generate as well so you can, you know, feed the segment. you can actually feed a signaling like sweep of frequency into here and you can generate stuff. so if you've got yourself a PCB it's just random PCB lying around then you can actually generate a field in here and actually try and couple that in your product so you can test for our electromagnetic conformity in that way that external magnetic fields at a certain frequency as I said, you can sweep it over a frequency don't interfere with your product under test. so heam used for our sensing thing fields as well as generating them as well.

If you want to use them in the reverse direction and these go for under 400 bucks, you can actually buy them on Amazon I Just had a quick squeeze I'm not sure what you know the price is anywhere else but in certainly people are selling them on Amazon and you get a cow suit if you get with it as well. And these are our four probes. Yeah, we've got our 3h fuel probes. so I assume H20 is like the twenty millimeter diameter, ten and five I'm assuming that's what those means.

So the 3h field probes over the full three gig frequency range or 300k actually three on okay, two, three gig and our afield one as well. But if we have a look at the manual, we can probably find that the E field is different. Yes, First page here we go. This is what I'm talking about.

So what your magnetic or H field probes are going to give, they're going to give an output power in DBM versus frequency. So this is the response for the different sized ones. So there's a twenty millimeter one like that which drops off at about a gig there or there, abouts and the various sizes and then for a given field of one micro Tesla. So if a know an input field, unknown input magnetic field in Tesla's will give out a certain output power DBM versus frequency.

whereas your ear field probe your electric field probe is basically entirely different because it's an electric field which is. volts are specified in volts per meter. So once again, you have an output power here versus frequency for a no and field a fixed no, an input field of one volt per meter. But not only are they useful for our pieces like just bare PCBs like that to try to I check out traces and you know and components and all sorts of aspects to your PCB design.

They can be used on final enclosures like this so you can actually go around and find that. Okay, we've got some leakage around these. You know these RCA ports here or around our HDMI for example, so you know, but it's an art in its own right. actually doing a proper EMC pre-compliance measurement? Something to do.

you know they'd have to be hours and hours of instructional videos to actually you know to to go through all the ins and outs of that. But yeah, these things are really very nice. If you're developing products, it's a really cheap way to you know. make sure you're at least in the ballpark before you go to your EMC test house and you can spend you know, like time and money.

Of course time is money so even more money by going this you can make sure your design is you know have a good chance of success. But of course you've got to understand the the various standards and specifications and how to do the measurements and all that sort of stuff. So maybe all that stuff is on the tech Box website. So with a cheap spectrum analyzer like this Roy Gold DSA Eight One Five and an air-filled our probe kit and the listen devices I have put in a I've done a separate video on also from our tech box as well which I'll link in down below for EMC pre-compliance I already have one video on that but these are your and you know for under 400 bucks to get one of these near-field probe sets you can do complete EMC pre-compliance for like well under two grand and that is like trust me, that's unheard of.

I Mean it cost an absolute fortune. just you know. fire. Just five or 10 years ago you had to have a real high in spectrum analyzer but now they're really cheap and these have got.

you can buy the EMC pre-compliance plugin for this as well which helps you more easily meet the standards and stuff like that. But anyway, this won't be a proper video on NC pre-compliance Just playing around here to what, see what we do. and I've got my ear filled probe in here and we can probe around and actually have a look at not a circuit but just the K, the inter connecting cables and the spectrum analyzer itself. Watch what happens if we put this over our cable here.

look at that. We're picking up something at 900 megahertz there and you see it has to get very close. This is what on the shield of the cable here. This is why it's called a near field probe because it has to be near to the product so or near to the item that you're trying to test and right at the B and C right Usb down in there.

and at that headphone output jack. Well look for sticking in that headphone jack. It's really going off the off the scale and you know nothing's a sort of escaping from our end connectors here. or anything like that.

it's just fine. But our around the USB and everything here, well, is something huge happening at 900 megahertz? and then we can have a play around with this HDMI board we were looking at before and we can probe over that? I've got like the full span here and we're probably not going to see a huge amount get over the crystal there. Yeah, there's something happening down the low end as you'd expect. so let's I mean this is over the full 1.5 gig.

So let's go down to the low end and see what's happening down there if we probe our crystal again. Bingo. Look, we've got a a peak there at thirty Six Point Eight Five Megahertz. That's not surprising because this is a two point A are twelve Point Two eight megahertz.

So there so one third of that frequency. so we must be getting out a harmonic there. so expand that out. And here we go.

We've got our fundamental here around our clock. There, there were our crystal and that's twelve Points are -. Well, it's but it's mark Twelve Point -. Wait, we're getting twelve Point Two Three Megahertz.

They're near enough. and then we've got out one of our harmonics here at 36 a multiple of that, of course, three times that at 36 Point Nine Six Megahertz. So you can actually probe around not only parts, but you can follow traces and things like that and find any signals on your board. Really quite mint.

neat and you know it just lets you do. And if you know what the standard is and you know that all it's not I screwed up the layout on this and it wasn't supposed to emit there and you know all that sort of jazz, then yeah, you can find this stuff really easily with these sorts of near-field probes. Now the way you typically use these is that your Fel probes are basically for very close direct contact here, which is why we're seeing nothing until we go like directly over the crystal there. so you can pin like a track down like maybe individual pins or individual tracers on large-scale stuff it's harder on, you know, really fine surface mount stuff like this to like? try and pick it up.

Whereas your magnetic field your H field art probes are designed to pick up your larger loop areas like your ground loop areas which is one of the big things for M C Compliance is that you have to keep the golden rule of a piece of allows keep your ground loop or your loop areas small so you're and that means going from your power supply all the way out. The loop area includes your ground on here include your ground system plus the power wires to get there and any signal stuff. so it's an entire you know and where the current flows in the entire loop. and that's where these H field or magnetic field pros pick up.

So we picking up a lot more crap as you can see going around here with our H fuel probe. We're not just picking up that individual crystal so we're picking up all sorts of all sorts of crud on here due to you know, other clocks or other signals that are all looping around this board right back to the power supply. So that's the difference between the H field probes and the E field electric probes. And one of the things you can do too is you can use the demodulation functions on.

there's a lot of the old gray beads do this. They will plug in some headphones here, that's why it's got a headphone port so you can demodulate the signals and you can actually listen to it and you know or yeah or your Greybeards have go around you know, scanning the board, listening in the headphones, stroking their beard with their other hand with their third hand and going here. there's your problem. And if you still a bit confused over the H field versus he field thing, well just to remember what EMI is what it stands for electromagnetic interference and OMC electromagnetic conformity Electromagnetic.

There's electric fields and there's magnetic fields and depending on whether you're near field, far field, whatever or high voltage, low current, or high current, low voltage. that kind of stuff that depends on which field is going to dominate and which you can actually measure. So generally speaking at at high voltage low current are stuff the E field is going to dominate. So you're going to want to use an E field probe for example.

But for high current stuff then which is going to be as I said likely you know. loop area. Big loop area on a PCB and you know as a chip just drawing. you know huge gulps of current or something like that generating big magnetic fields.

Then generally at a specific distance they are the H field. The magnetic field is going to dominate so you're going to want to use and magnetic field so they just keep that in mind. EMI Electro Magnetic. So thank you very much Tech Box This is an awesome must set.

It's going to come in real handy in the lab authorities down there. It's empty. Um, but yeah, well worth the dollars if you're doing EMC pre-compliance As I said under two grand for right something like this, you can do it really well. I Mean it might seem like you know a lot of money, but it saves you a ton of money.

One of these things and pretty essential if you're doing that product development. and it's also essential to get the calibration certificate with it as well. so you know the exact performance of this. So because you're actually doing quantitative measurements here, trying to at least see you gonna get in the ballpark of passing your Us standards so you know you know you're also paying for the for the calibration and certification of these things.

so very handy. I'll linking these art down below at Tech Box if you want to check them out. So I hope you enjoyed that mailbag it was I didn't open as many as I thought I would and I've got a massive backlog and not only the ones I got through today I got even more today turned up. If you're following my art Twitter feed you would have that seen the photo and this huge looking Tektronix box has come no it's not from at Tektronix it's from a viewer so I'm gonna I might do that.

one is its own mail bag cuz I know what's inside anyway. hmm I'll leave you guessing. catch you next time you.