Two +5V rails, neither of which are used. 🤣

This oscillator circuit is notoriously unstable. One can even try to use a crystal to overcome it but it behaves erratic at times. If lucky, it may run stably. As a side note, the photodiode BPX65 proved to be very unstable in time when used as a detector. Its gain permanently slowly changes over time. There are extremely stable photodiodes available, like S1223 from Hamamatsu.

Is the output of the SAVI board isolated from its input?

This is an easy one... It's a small company with a low production product. You use a COTS power supply up front like that since it has all the safety approvals therefor, there is a whole boatload of certification testing that you don't need to do.

These came out of a outdoor fiberglass enclosure that housed these power supplies and a data module for a RFID scanner. Got a pallet of these systems at a government surplus auction. The RFID scanners were used to keep track of inventory as it was being deployed at sea ports or air ports when military units deployed. The brand of the equipment is SAVI, just Google the brand name. They still make and sell RFID scanner systems. Each vehicle or large piece of equipment has a large RFID module stuck to it and the scanner system has antennas mounted to tripods to scan them as they get into range. I bought the lot because it came with several hundred feet of LMR-600 coax, several heavy duty antenna tripods and the nice outdoor fiberglass enclosures. Also got about 2 dozen 2.4GHz antennas in the lot which is the frequency range the RFID tags operate at. In the enclosure they only used the output with the wire attached and connector. That's what supplied power to the data module. It could have EASILY been powered by a wall wart but we are talking about equipment made for the military. Rule number one when making something for the military, make it as complicated as you can and charge 10 times to much for it.

Is the battery input not a kind of backup when mains power fail? Have you meassured the outcomming voltage in comparison to the output from the first supply in regard to ripple and noise?

Need component list , suggested vendor, and solder mask please. Is a preassembled board available? Would love to see a 3D printable case for this project. Great project and related videos! I bought a very similar attenuator Weinschel model 3200-1 off of eBay and bought your board from PCBway. Now for the components and solder mask. Looking forward to building this project. any and all advise welcome. Thanks!

I'd say, it was engineered by politicians.

Go figure.

I like it! Especially if you imagine this being in a very low volume product where the BOM is essentially negligible and everything they can do to save engineering hours is a big profit win!

+5 and +/-15V would be great for an Eurorack modular synthesizer, though I'd rather use a linear regulated classic supply for the analog circuitry. Cool dual source design. Makes sense. Dang nice DC barrel jack there - I love indestructible parts!

Hmm? Maybe a one-off quick-fix battery backup solution for powering an "EXIT" sign.

You said it was a odd design at first, but it is obvious that the secondary control circuit is actually used to avoid the hiccup mode caused by low starting current, which is the weak point of SMPS systems.

The Bayesian priors I like to use for unconventional and surprising actions are: 60% likely due to laziness or cost-cutting; 38% due to incompetence or lack of information; and 2% due to malicious intent. And, jokingly, π ± 17% if you are bad at mathematical reasoning.

I just got two of those off the shelf 3 output power supplies from Digi Key it has +5 and -12 and +12 it is listed as a PT-65 or PT-45

Of all the questions I have about that, the main one is "Where did you get that?"

That's pretty weird.

first :)

Wurth Red Expert: internal server error!

Dear Sir For HTL25 . Please look for MC10ELT25. Which is 5V TTL translater Stay safe Baha

I took a university elective course on "Power Electronics". Personally I just thought it was a class to sell the professors book - LOL. The course was exclusively about SMPS designs and theory - which was not what I was expecting from the title of the course. It was one of those classes, and there were quite a few, where I got at A, but several months later I could hardly remember anything about the topic being taught.

Just re watched these. Great fix. Engineering solution in the year I was born. Progress is materials science and engineering catching up to theoretical understanding.

It's an European company, so they have to stick to European privacy laws. I don't think they will spam you crazy... They sell components

This has been a standard marketing publication type in the electronics parts world for 50+ years. I would typically go to a trade show and get a whole book case full of marketing materials free of charge. I remember ordering a whole series of books on TTL IC Circuit design in like 1983, I was 13 years old. Got a whole bunch of big books mailed to me for the price of postage, or free. Looks like they defray their printing costs now, and that's what makes them seem cheesy when you BOUGHT a book. I learned a lot as a kid in the 1970s and 1980s from these free publications. Cheesy those these are, I like them. There needs to be more, on a variety of topics, for non-engineer audiences, for people who are just messing around at home with an arduino and a breadboard, and maybe have some project in mind, and may need a variety of general handbooks for various electronics topics. What we have here is an interesting capture of the evolution of this marketing strategy. These days they want you to show up at their web site and key in your information so they can blast you with 200 emails a week.

With that channel name I have to subscribe!

I was able to download Wurth's Trilogy of Magnetics for free a couple years ago. They sell it now. ToM is 827 pages(wow) with a 70 page chapter on SMPS which looks like topic arrangement of this new "book". Everything gets monetized these days. I draw the line at buying subscriptions to software.

Thank you for doing the video about this module, great video! I'm the one that originally requested it ;). The original reason that got this module my side, was to maybe, if suitable for the purpose, use it to protect my Commodore 64 (C64) retro computer, as apparently the original 5V (at 1.5-1.7A from what have found online) power supply bricks can fail and put out around 9V(?) and anything 5.5V or over, damages RAM and other chips in the C64.

You need to test the overvoltage range to failure. It is useless if you don't know the max input voltage it can protect against and if it fails shorted to output or ground.

Something this dude missed: The cover says this is mostly about EMC considerations. This is not a book for general converter topics.

.Wurth does make excellent caps, inductors, ferrites, etc. Could be a worse company. Edit: how has this dude never heard of Wurth? Isn't he an engineer? Major electronics component company.

Book of the day! Finally!

The best resources I found for this topic are application notes for chip manufacturers, the only issue is they usually try to use thier own ics and force too much ics in their design

Yeah but how does this fancy ic get powered ?, zener ?

Very nice and interesting... Lovely

No discussion of Cuk converters, forward converters, or flybuck converters? That's disappointing. But if anyone needs *heavy* details on converters, Sam Ben Yaakov has hundreds of hours of lectures and calculations on his youtube channel. A great resource, but not nearly as enjoyable as your channel. That actually reminds me - last night, I was thinking about opamp based capacitance multipliers, and I've never fully understood when it's appropriate to use them... Or exactly how they work, and I wished you had a video on them. Your explanations tend to make things click for me.

I've had one of those OCXOs in my parts drawer waiting to be paired with a GPS receiver for... about a year now. PT8211 + RP2040 seems like a good pairing to tune the XO and (eventually) synthesize whatever's needed to replace the crystal on a GPS module, while offering various divisions of the clock, and monitoring PPS (probably disciplining from PPS too for a while, until I work up the nerve to un-can a GPS module) One personal problem though, is I have very weak GPS signal at my house 95% of the time, so I suspect I'll need to invest in an outdoor amplified antenna before I can get that off the ground... in the mean time this nicely demonstrates it's stable enough when tuned by hand for various benchtop applications, so I think I'll mount up an SMA connector and dead-bug it to life.

Thanks

I have been following you for a while, I like most of your posts - this one is no exception. However, I do not find this book expensive: "The Art of Electronics is Expensive". Moreover, it is on Amazon with a Kindle edition at $13.

Online calculations? I hate online calculations, I hate online tools, I hate online simulation, seeing the common thread here... I hate online.... anyone who has been online for years /knows/ that you cant trust it to be online when you need it.... make it a program, make it an app, but make it a standalone download so when that sunspot or emp hits we still have it.... Only 8 month ago I bought a package that runs on my pc, didnt realise it only runs from my hard drive on my PC after its done a handshake with their remote server to see that I have paid for it.... what happens to my 69.99 software package when they go bust and the server is sold for scrap..... stay OFFLINE

RECOM gives away a similar PDF mm.digikey.com/Volume0/opasdata/d220001/medias/docus/2151/DC_DC_Book_of_Knowledge.pdf

Wurth is a manufacturer of electronic components - that's the sales pitch. I think they make inductors and transformers and such, but they make a bunch of stuff. Which is where the sales pitch comes in. Of course, to be honest, this book looks a lot like one of the books a company would put out for free for marketing purposes. They are all relatively basic, but a good introduction with the goal of marketing to you. I'd bet they probably make an ebook version of it for free to save you the money of ordering and shipping from Europe (making it really expensive).

Wurth makes magnetics (cores, inductors, transformers) and other components including power devices.