Hi welcome to Tear Down Tuesday Where's the thing I'm going to tear down? well sitting on top of my video camera and I'm using it right now to record the audio for this video. It's the Zoom H1 Handy recorder and here it is: Oh I might be peeking a little bit check, check, check. Definitely going to peek there. It's a little uh, handy uh wave MP3 Stereo recorder and it's got an external mic out and you can use it to uh record stuff for your video.

Let's check it out and here it is. It's a very nice little compact bit of Kit and I Love it It uh retails for like under a 100 bucks and it's a stereo uh MP3 or wave recorder. It's got a selectable MP3 wave switch on the back there. Let's have a look at this.

It's got a auto uh volume level on and off. It's got a low cut filter which is great for uh uh, actually cutting out low frequency noise and possibly some um, handheld noise if you're using it as a handheld mic. It's powered from a single ablea cell in here. It's got a standard Um thread on top for mounting on top of your camera or on a little mini tripod and uh, it's got a nice uh LCD on it which um has a proper V level meter.

It's got a basic uh start, stop, record, uh function and it's got a power switch. It's got USB uh interface so it can be used as a USB mic and it's got uh, some basic uh uh playback, uh commands input level so you can have Auto or manual uh LEL level set and it actually has an external microphone input as well. So if you want to use a better quality handheld mic or something like you can stick this thing in your pocket and you can use like a external handheld uh mic, then uh, well, you can certainly, uh, do that. use it as a portable recorder or a line in as well so you can use it to record stuff from like a tape deck or something like that.

It's got a clip um level indicator here so if you're uh, input Clips then it'll show you that and it's got um, these stereo microphones down in here and uh, they're in this crisscross uh fashion because that makes them equidistant wank word of the day equidistant from The Source regardless of where the audio source is, if it's right out here, or if it's out here or it's in front like this, these are the same distance so there's no phase difference between. um, if you had a traditional uh stereo microphone, they would have two separate uh mics like might be out here and if your source is over here, there's different uh lengths to get to each microphone. so by putting in this cross configuration like this, they, um, just work and apparently it reduces the uh, any F any um issues due to phase and it's supposed to increase the stereo Imaging and all that sort of audio wank word stuff. But there you go.

It's a very nice little handy recorder. Oh, and it's got volume and a speaker on the bottom as well. and it's got a Micro SD card in there to record your uh stuff directly on. it's very nice little recorder.

I Love it! So let's open up this thing and uh, see what's inside now. I Expect a uh micro processor I don't know what? uh type. It'll probably have an M because it's got MP 3 uh encoding, uh capability. Maybe there's a separate MP3 encoder chip or something like that.

Or maybe it's built into the main micro and there'll be an analog to digital uh converter as well. That'll be a 24-bit type cuz this thing's capable. Um, it's got a 24-bit analog to digital converter up to 96 khz. uh, sample rate.

so you know it's pretty highend stuff. I Expect there to be some uh, shielding uh in there because we're talking about, you know, a 24-bit uh converter. So so, um, there won't be a terribly, uh, a terrible amount more than that ADC and a micro and uh, maybe an MP3 encoder and some miscellaneous uh circuitry. Some uh, level, um stuff.

So there'll be some analog input circuitry, but that's probably about it. The micro probably uh, controls the uh SD rights directly to the SD card and well, I don't know. we'll find out. Let's open.

It looks like we got two screws there and let's see if there's a another screw inside the battery compartment. Doesn't look like it. So uh, take out these two screws for starters and maybe it just, uh, lifts off like that using my spudger here to there we go. It's got a clip in there and a clip in there and it's probably got another one up the back here, but it looks like it separates like that.

So yep, Bingo looks like there's another clip up the back and Tada there it is. Now that's rather interesting. The first thing I notice, of course, is this, uh, copper shield in here on top of this board. It's solded at a couple of points down in there and uh, that's rather interesting I Guess they decided It's almost as if maybe it's a, uh, maybe it's an after theth I'd have to have a look at the Uh PCB pattern down in there.

But anyway, we've got our flat Flex cable going over to the Uh switch uh switches on the back of the unit here. so um, it looks fairly, uh, compact. They've really, uh, jammed a fair bit of uh, electronics physically in here. These uh, these tall surface mount electrolytic capacitors fit in this space up along here.

and uh, this board here is clearly the Uh DC Todc converter because you need that because it's only a single cell, it's only 1.5 volts. I don't know what voltage it actually operates down to maybe 1.1 minimum. or if it' be nicely designed, it might be 1 Volt or 0.9 volts minimum. But um, uh, you obviously need a boost Step Up DC Todc converter for that and I Looked at that chip under the microscope and it doesn't.

uh, it's not identifiable. It uses some weird code Mark But uh, there you go. It's a basic boost converter. You can see the gold test points there there there and there there for the production test jig.

they would have a bed of nails uh, tester that they would test each individual board on. Now, this is rather curious. They've got the USB uh mini connector there connected, uh, solded onto the DC Todc converter board up the top here. and uh, really, that's very.

That's quite strange because you'd have to get the Uh data connections off this board. So presumably it's got a either there's a ribbon cable under the bottom that connects down to the bottom board, presumably where the processor is, or it's got to go through the DC Todc converter and somewhere else. There could be a processor over here perhaps I haven't lifted that flap up there, but it's got to get those data connections all the way through that DC to DC converter. That's just a rather unusual placement for the USB connector.

And check out the footprints there for those little surface mount resistors or capacitors there. They've got no solder masks removed, so they've decided that they don't uh, want want to mount those components and they've actually, uh, haven't they've actually, uh, closed off the solder MK for those so there's no solder on those pads at all. Um, that's not, uh, fairly common. usually on unpopulated Footprints Like that you you would just leave the solder mask open and you'd see the Reflow solder on those pads, but not in this case.

Now let's take a look at this side of the top board, the or the blue board as we'll uh, call it here and uh, there's this plastic is that looks like a plastic protecting uh, there's another copper Shield under all of that and that's not. uh, very surprising because these are your uh, input and output connectors here. So this is all your uh, audio stuff, your analog to digital converter, and your uh Dack and stuff will be all under there. and possibly well, the um, actual processor is probably down on the bottom green board down in here and I'd say this is uh, all of your ADC and uh amplifier stuff cuz it's got to drive the speaker which is all the way over here by the way.

and uh, so let's take a look. let's lift up that, lift up the skirt and see if we can find anything under there. We may actually have to desolder the shield. jeez I Hope not.

And of course you can see the microphone connections there and there as well. So this is really, uh, that's why it needs all this shielding and uh, I can't seem to get that plastic off. It seems to be stuck down well and truly adhesive stuck to the uh copper board there, so looks like we are going to have to desolder that. Bummer.

There's the circuitry underneath. There's a couple of devices there I'll put those under the microscope and see if I can get some numbers and there's the main device there. It's a Texas Instruments AC 3101 so we'll have to check out the data sheet for that. Well, no major surprises at all.

It's an off-the-shelf stereo audio codec from Texas Instruments it's it's a Tlv 320 AIC 311. They don't put uh the extra uh info on there, they just stamp the chip 3101 but you search for it and it uh, pops up no problem at all. It's got an Dack and an ADC. The stereo audio uh Dack here is got 102db signal noise ratio um, sample rates up to 96 khz.

It's got some uh, wanky effects as well based treble 3D stuff and D emphasis and things like that. they're probably not used in this particular Uh product. And the stereo. uh ADC down here at 92 DB signal to noise ratio support sample rates up to 96 khz the spec on this thing.

It's a Uh classed as a 24-bit analog to digital converter up to 96 khz. sample rate. Um, it's got some DSP stuff as well and noise filtering available I'm not sure if they actually use that, they may. It's software selectable and it's actually got six audio inputs.

It's got one stereo pair single-ended It's got one stereo pair fully differential inputs Um and it's got six audio output drivers. Wow! It can drive uh, differential and single-ended headphones. It can drive stereo line outputs. Hence, this thing's capable of dual headphone and line out uh capability.

Um, and it's got a 500 M um speaker driver as well. They're probably not uh, driving it that hard in this thing. It's only a tiny speaker in there, but it's capable of doing that. It's low power.

it only takes 14 M um. During uh playback, it's a 3.3 analog. Supply H what else we got? It's got automatic gain control which uh, there's that switch on the unit which um selects. uh, automatic gain control on the input or manual.

Um, it supports Um, it has microphone bias as well built in. you would need that for these uh electric, uh microphone inserts and uh, it's got an nice Squ C control bus for setting the data and it uses the uh no surprise as most of these audio class codecs do. They use the Um I S S uh not to be confused with I Squ C I S S uh audio interface um industry standard type thing and it's in a 5 mm X 5mm 32 pin Qfn. Let's take a look at the block diagram and it contains a lot of uh, analog and digital stuff that would ordinarily require a an awful lot of uh, separate uh discrete circuitry.

So um, the inputs here. It's got a programmable gain amp from Zer to almost 60 DB and half DB steps. Wow into the ADC It's got the auto gain control there. it's got uh line inputs, it's got the microphone amplifier here and a summer and there's the I2s uh audio uh interface and uh, it's got some switches, the effects processor down here, volume controls, and then another Dack oh jeez, and then the output.

all the output MKS in for the um uh, headphone, uh outputs and the line outputs as well. and the of course all the I Squ C control, uh, data interface, and uh, the clock generation as well. and then the microphone biases and the different voltage supplies it needs. It's a really heavily integrated device and if you take a look at the typical circuit configuration here, you can see that uh, the I2s interface connects to a DSP or an application processor.

We could have yeah, a DSP or a microcontroller bit because this has to do MP3 encoding unless there's a separate MP3 encoder uh chip on the other board which we haven't uh seen yet which is uh, quite likely then it would need a fairly heavy uh DSP cuz it's not easy to do MP3 encoding on a low-end microcontroller, but uh, pretty basic stuff. It's got the microphone um, electric microphone input here with the microphone bias Supply AC coupled Pretty standard stuff. um, line inputs here also AC coupled, uh, another uh line input here and uh, well, it's got a whole bunch of line inputs and then the uh, um, headphone uh, driver down here and external audio. uh Power Amp So it's recommending, um, if you know, a separate external amp if you want to, uh, drive a decent uh type of uh speaker load instead of uh, headphones and uh, lots of decoupling over here for the built-in uh supplies.

so uh, there's a whole bunch of uh stuff. analog. Vdd is rated from 2. 7 to 3.6 and also needs uh for the Iio as well.

Go can go down to 1.1 Vols uh to 3.3 so that's rather neat and that's all there is to it. and you'll basically, uh, find that, uh, all this stuff will be mirrored on the PCB It's just got a whole bunch of uh, coupling, uh, caps and decoupling caps and a couple of pullup resistors and that's about all. and that's what we see on the board. now.

This is rather interesting I Highly recommend you, uh, read the data sheet if you want to know how the uh AGC setting works I haven't read the manual for this thing. Maybe it explains fairly well, but this is you know, coming from the horse's mouth directly from the Uh chip manufacturer's data sheet. cuz Agc's automatic gain controls can be rather tricky and if you use them, um, you know you've got to know exactly how they work under what conditions. Otherwise you could end up with uh, things that are clipped or too low and audio that's all over the shop.

So you want to know about the Decay time and that's actually selectable. so who knows what decay time that they're actually using that What? They've set that in software? um, hardcoded that into the uh, firmware of this thing. So if you go down here, it can show you your input signals and your output signals and how it, uh, adjusts that in, uh, real time. So if I'm recording like a lecture or something like that, I'll set the level up up manually.

I'll place the things set it up so that I know that uh, it's going to give me a consistent Audio Level and I don't have to rely on any tricky business happening in the Um AGC And there's a digital audio processing for playback and there's all sorts of stuff in this data sheet. so I Highly recommend you. uh uh, Check it out if you're interested in how this sort of stuff works. And the D digital interpolation filter.

and ah, the Delta Sigma audio deex, it's all in here. It's great stuff Excellent bedtime reading. and the other part is a Jrc 2100 A4 not familiar. We'll have to check it out.

Maybe it's uh, some sort of uh, you know, dual Opamp or dual microphone amplifier or something like that and I was right on the money. On the other Uh device, the Jrc 2100 is actually an Njm or New Japan uh Radio 2100 dual operational amplifier. No funny business going on there at all. It's just a low operating voltage plus - one volt to plusus 3.5 Vol single Supply Operation Jeel Op amp No more to say there.

And if we have a look at the Uh Duwal board construction here, uh, I was able to lift out the microphone insert over here and you can see the board-to-board interconnect they've got down here. and uh, there we go. We can see the bottom board. We can see the Uh side switches directly uh, right angle side TX switches directly solded onto there some test pads that would be for programming the microcontroller that would be the JTAG Uh interface.

I Haven't even looked at the Uh silk screen there, but that's obvious what that is. A couple of more side tactile switches up here. There's the uh uh, flat Flex cable directly solded onto the board, a whole bunch of resistors neatly laid out in lines I Like that when you're laying out aboard, it's rather neat and uh, let's go in and see if we can can find out what sort of processor that thing is and you can see the uh. other bunch of electrolytic uh caps for the Uh for the coupling um, input and output coupl in here.

These large ones would be Uh for the output coupling for the headphones, and another, and some of those would be used for the input coupling as well. One rather interesting thing to note is you'll notice that the shield of the USB connector has this black wire running all the way up to Uh, presumably one of the Uh grounds up here. one of the analog grounds right up there, which might be connected through to the shield on the top. I'm not sure, but uh, obviously that's like a maybe an afterthought, perhaps? um, or maybe that was the easiest and best way they could get that all the way back to that on the double-sided board.

Uh, who knows. but uh, they've obviously had to do that to uh, uh, get the noise down in some Uh way, shape or form and you'll also notice the extra circuitry in here for the DC Todc boost converter. Now, if I take out these little plastic Clips either side here for the uh, uh, plus minus buttons, then the board seems to seems to lift out somehow. perhaps very gingerly.

I Don't know. this could be tricky I Might have to, uh, get some pliers there and pull it out vertically. Perhaps There we go I got it? Aha, there we go. Now we got some serious stuff happening.

Awesome And bingo, there was too much uh happening to all be on that one tiny chip on the top. So obviously we got some sort of processor here. We'll check it out. One of these is probably the MP3 encoder.

We've got our SD card directly mount on the board, another device over here, our tab mounted uh LCD custom LCD display over here, our carbonized PCB button which connects to the rubber uh button for the front panel for the record switch, and a few miscellaneous things, and a real time uh clock for the time and date. that's the 32 uh KZ Crystal and there's another Uh surface mount connector up here, which they decided not to populate, and there we go. The main processor is a DSP it's the classic Texas Instruments TMS 320 series and the first device we've got up there is an En 39 Sl800 and that's an 8 megabit flash memory and the other device we have there is a core Magic. Haven't heard of them before, but it's a CMS 3216, L-75 and I believe that's actually an SRAM.

So there you go, we have a Uh Texas Instruments TMS 320 DSP processor. We have external flash and we have external SRAM Now interestingly, this is a TMS 320 C554 4 and it already has Uh 256k of build-in SRAM and 128k of ROM. That's not a huge amount of ROM, but it is a lot of SRAM. But maybe they need a lot more so.

Uh, Given given the proximity of these two devices to uh, the TMS 320 up here, this does actually support external memory up to 4 Meg. So it's most likely that they are actually external uh Flash and SRAM for the TMS 320 processor. Now, the thing that's missing, of course, is the MP3 encoder capability and that's even built in to the TMS 320 and I'm. sure it's probably uh capable of doing that, but there's this mysterious device over here which we couldn't identify which is close to the connector uh, going through to the top audio boards.

But of course, one thing the TMS 320 processor is not going to have is an LCD driving capability, especially to drive all the segments that are actually on this display. It's it's a large number of segments. so um, clearly. Also, given the Uh location of this Uh micro, here, it's It's pretty obvious that uh, this is the LCD controller because uh, it's close to the Uh tab.

uh, the tab connections on the Uh left hand side there. So that's some sort of maybe custom or rebadged LCD controller. And that means that the MP3 encoding must be done in the TMS 320 processor. Hence, probably all the extra Uh, external, Uh, SRAM and ROM required.

And for those curious about the copper shield in here, that's uh, clearly all over this uh, digital circuitry here cuz we've got parallel Uh buses running between uh, the external memories and the DSP and maybe you know around here we got the SD card so you know there's the Uh main Crystal oscillator for it by looks of it. So all of that sort of stuff is running. you know it's going to be running at a reasonable frequency and it's all going to be uh, digital stuff so they've obviously just uh, shielded on there Now whether or not that's an aftera, uh to meet EMC or noise compliance or uh, something else after they did testing I'm not sure. and based on the looks of uh, the pads designed into the PCB to solder this uh, copper shield in down onto it.

um, it's at least uh, thought out as part of the uh PCB PCB design so it's not just a you know, it's not just a hack add-on or anything like that after the fact, but maybe it could have been. maybe they did their original uh testing and they found oops, You know, we probably need this copper Shield all the way over here so they might have respun the board to uh, add in the Uh pads there for the shield. who knows, or they could have been smart and designed it in to begin with. Your guess is as good as mine.

So there you go I Hope you enjoyed that. That's the zoom H1 Handy Recorder I Rather like it. it's a nece neat bit of kit. It's a, actually uh, fairly welld designed and uh, fairly compact.

They've put a lot of thought into maximizing uh, the amount of circuitry inside the 3D envelope in the case to, uh, keep this thing quite tiny. they uh, couldn't have made it much smaller without a significant, uh, more amount of effort. and it's like less than 100 bucks. So uh, if you're in the market for one of these things I Highly recommend you pick one up.

They're very neat so if you like tear down Tuesday Please give the video a big thumbs up cuz that really does help a lot. and uh, if you want to discuss this thing, uh, jump on over to the Evev blog forum and there should be uh, some photos on my flicker account as well for you to check out eventually. So till next time. see you.