Hi Welcome to the mailbag segment again! Yes! I Can't believe the popularity of this mailbag thing. People seem to love it. The number of views is massive. The last one got like 177,000 views or something incredible like that.

I Guess people just like watching me open my mail. It's incredible. So please keep sending me and uh, we'll open it live. Live quote marks on air here and uh, see what it is.

And we got three items today. one from Poland. we'll take a look at that one from Parts Unknown but somewhere in Europe and uh, one from Elector. So let's check it out.

That one's lots of stuff in there. Let's go now. the first one here is from somewhere in Europe. It's uh, got 50 here.

didn't cost much at all. It must have been sent as a letter instead of a parcel. And check it out, it's addressed to Sector 7g. Do! and if you don't get the reference Google it and of course it's amazing.

It found its way here at all in the Eev blog. Tower is bigger than the Empire State Building It's huge so there's the address if you want to send me the stuff and uh I can't find any other info. Hang on. What's that? We got Retro Rena as in Rena the Car Retro Reno.com Let me go Google that one and I did just Google that and well, it's exactly what the name uh says.

It's just a uh like a a user community site for Rena or anyone who owns a Retro Renault I guess I certainly don't. So anyway, go figure. Let's uh, open this out it. It looks like it's a used envelope.

if you have a look up there, maybe it's reused and that's where it came from, so it's probably wouldn't surprise me if it's not from anyone at Retro. Renault So let's open it up and take a good look inside here. Tada Looks like we have a board or something and we have a note. nothing else left.

What does the Note say? Hope it doesn't have someone's address Here we go. Yeah, by the way, if you don't want your address on the uh segment, please don't put it uh on the letter because I'll open it. Live here! hi Dave Enclosed is your very own Xr25 PCB USB adapter board kit all the way from Ireland Awesome hi to all my viewers in Irand It's an adapter to allow you to connect an FDI TTL cable to the open collector. diagnostic output Oh, on older Renault cars, it is there you go.

Okay, so it's not particularly useful for you, but I wanted to send you something and DeLorean use an old Renault engine and of the same diagnostic port. So someday I'll put it to good use I may indeed, thank you very much. Chad PS Can you hold on to that pink bag and bloke down? the pub said it would keep your family ESD safe? Excellent! More details and instructions can be found here at Chat. He's got his own Uh website with theie address in Ireland so check it out! Beautiful! and let's check it out.

What do we got here? pink? ESD bag. We've got some components blah blah blah and that's it. Oh, not much on it. It's not even a micro look at that.

it's just an L U1 There we go. Retr Reno.com Diagnostic Ground Diode? That's it. Geez, you don't need much to uh to hook up to a retro Renault Let's have a look at what this device is and it's just a Bc557. There you go, so thank you very much! Chad And if you're into Retro Ros I guess you should check out Retr Reno.com next up here we have one from Poland and let's have a look at uh, some of the stamps.

I Do enjoy looking at stamps, so that's uh I don't know that's I'm not even going to pronounce that. Maybe it's one of their cities and that's the skyline. perhaps? not sure who or what that is bizarre and uh, some obviously uh, famous, uh, famous? uh building or something in Poland There you go. Awesome and it's from I Think we have something here here we go Sebastian Ola Thank you very much Sebastian So here we go.

What has Sebastian Sentus? we have very. it's not a another kit. Excellent nicely. uh packaged in the static shielding bag I wonder what it is? There's a whole bunch can massive big mosfet in there or something.

We'll take a look at that huge device. Absolutely enormous and uh, that's it. So Let's uh, check out what we got here. Oh, looks like an amplifier.

Brilliant! Hi Dave I'm sending you this kit of an easy tobuild, 100 watt highquality audio amplifier. Here is a quick history of my project similar to your microcurrent and other projects solving some problem. The amplifier was designed by M Bitner and published on his web page. Only the PCB design is mine.

I don't hold any right to the schematic. The Sim Asim 5 later 5.3 has become a sensation. W It's a sensation. People from many countries including Poland very highly began to make these devices.

However, the original Sim Asim if I'm pronouncing that um Sim Asim as in symmetrical and asymmetrical PCB design was foldy and many users complain about the problems. Common issue: unstable operation PCB was too big and looked like it was designed by someone who had no experience. Woohoo! All right, while designing the circuit, I was doing my best to keep the symmetric uh, the symmetrical in both mechanics and currents. that has succeeded almost perfect.

Moreover, to fix the problem with unstable operation excellent, which was caused by too long and misplaced traces on the original. PCB Aha, Just a layout issue. Uh, not uncommon Um for these types of amps to have Um layout issues and be unstable. Uh, my board is about three times smaller.

Wow. Awesome! The Prototype was built in January 2009 and the THD is point approximately 005. Um, how did you measure that? By the way, if you can, uh, let us know in the Uh comments please Sebastian if you got like an audio Precision or if you got a some sort of THD analyzer or something. Anyway, this design was appreciated by Audio do-it-yourself audio users.

So I made a few pieces devices for them current Symmetry and shorten traces High impedance feedback Nice run. The most important parameter was the thickness of the copper layer over 105 microns which is considered audio file value. All right there. And there's the stack of boards.

Brilliant! So you made a few changes: 60 by 60 millimeters. Brilliant. Excellent. Thank you very much.

Sebastian And if you want to check out Sebastian's website, there it is Floods. info if I'm pronouncing that correctly. All right. So let's crack this thing open, get all the parts out, and check it out.

Make sure they don't go flying. Good thing is it's all through hole stuff so you're not going to lose any 0402 components. Let's check out the board here. Floodin.

It's a Sim version to and it does. There's quite a bit of symmetry there. I Like it. It's a nice decent layout, well done and let's have a look at the top.

What do we got here? Flodin Sim V2 again Sebastian Olia And uh, it looks good and and it looks like we've got genuine Tber uh TSA 1943 There these are um I'm not sure if these exact ones, but a lot of these. uh, very expensive. high power. uh transistors are often uh, faked.

so you got to be careful that you actually get the genuine Uh ones. And and this one here is a TSC 5200 and they're in huge monster packages. you would. If you're going to get uh 100 Watts out of this, you would really have to, um, make sure that you put these on a decent heat sink and get a decent thermal transfer through to your heat sink.

So this looks like all discreet design. One thing we didn't get is the schematic. Going to have to go look it up online and I thought I recognized the name Floodings: Uh, he's actually an Eev blog uh Forum member and there's a specific Uh thread that he posted on this uh project back in. January I think it was so I'll link that in if you want to discuss it.

that would be the thread to do it in here now. I Found the schematic. Uh, this is from the guy who originally designed it. um, his website.

Um, so I believe it's the correct one, but uh, if I'm wrong, please correct me now. I'm not an audio amplifier guy I'm not really into that sort of thing, but uh, nothing strikes me as un as unusual in, uh, this audio amp design at all. It looks, uh, fairly straight forward we got. there's our bias adjustment.

uh pot, there are output transistors, but then having a 10 Ohm series output resistor just, um, strikes me as rather odd I'm not sure if it's a mistake or not, whether it is actually uh, 10 Ohms or not. Uh, It's Not Unusual to see like a 10 Ohm output series resistor, but typically it would have an inductor in parallel with it and some other stuff. Just like we've got the um RC uh output RC directly on the output. here you would, you might have an inductor in parallel with that, but it doesn't seem to be there.

So uh, if somebody can, uh, clarify that, please do and you'll notice that the output transistors are different to what we actually got in the kit. Um, so they're obviously been substituted for some reason. either uh, cost or performance, or both in either direction. Um, you'd have to go check out the data sheets on the individual devices to find out why.

There you go. If you want to, uh, discuss the schematic, jump on over to the EV blog Forum I'll provide the link, thank you very much. Sebastian That's very interesting and if you're after one of these kits, I'm sure he'll sell you one. So go to floodings doino.