DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)

[prasimix]

Hi Guys. To the people that have their psu built. Where did you get your parts from?

Prasimix: with the group buy planed. Is that for a complete kit?

I think that will be impossible. Too many parts for making a kit. Maybe with THT but not SMT parts. At least that is beyond my current apprehension of electronic kit. When I think about group buy that is primarily for specific parts like PCBs, enclosure, TFT display, maybe some ICs like W5500, etc.

I really try to keep up to date BOM that can be found here. Yes, I know that choice of suppliers is not optimal. I found e.g. just recently that Farnell don't want to sell to private persons (only to companies). TME cover most of the world but I don't know what is shipping cost outside Europe where is bargain.
If anyone wants to compile e.g. Digikey/Mouser/Arrow or anyone else I can assist if some doubt arise and we can merge that BOM with existing one and make it available on the GitHub to everyone.

[Strada916]

Yes thought as much. Re kit. Looks like Farnell have 99% of parts so going with them. As I'm in Australia.

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[prasimix]

As far as I can remember Farnell is missing three important parts: AC/DC modules (if you don't want to use toroidal transformer), W5500 Ethernet controller and LMJ2138814S0L1T1C RJ-45 jack (last two are required only for Ethernet and can be replaced with cheap eBay module (see Hack #7).

[Strada916]

All good going to go with farnell. Eithernet will be via hack and module. Not sure whether I go toroid or ac/dc I have a toroid.

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[prasimix]

Ok, for transformer please use Power module AC input option from BOM instead of C1, C2, C3, L1 and X1 (optionally ZD1 too).

[timgiles]

I would be happy to to add in Mouser part numbers and put together a Mouser Project/BoM for you. Cant promise it will be this weekend/next 24 hrs, but over the next week should be able to get it done. Probably my preferred route for most of the parts as it is a tax free way to get parts in to Europe (Sweden for me). If there is anything I cant decide about, I will leave it for others to help with.

In terms of group buy - sounds good if it is for the larger components.

Regards Timothy

[prasimix]

Thanks Timothy for initiative. Let me know if you stuck with any components or found some errors in existing BOM!

[timgiles]

Just an update - I ended up sitting down last night and going through about 90% of the list. So another hour today should have an almost complete Mouser list. I have inserted a few columns and will upload the update to Github once complete. There were a couple of errors in your Farnell part numbers - I have marked those in the last column. There are a handful of parts I just could not find - an IC, the heatsinks (so hard to find if the same manufacturer is not stocked). So I have left those blank. The IC really needs finding - but I could not find a TI alternative. Prehaps you know Prasimix? Check it out when I upload the updated BoM file.

Where ever possible I have selected the exact same part. The BoM / Project (which I will add a link to once finished) is currently for the exact number of parts needed. However, this is more expensive than it needs to be. Quite a few parts, if a person orders slightly more, ends up being cheaper (50% of more) for that part in total. So, I will also add a second BoM / Project link that uses the same parts but minimises the cost overall by over ordering where applicable.

Finally - There are some parts that are just darn expensive from Mouser. I am thinking therefore of adding in another 'cheapest' BoM and maybe even a 'Guilding the Lilly' BoM as well :-) But that is all if I have time and feel the need to browse Mouser.

Regards Tim

[prasimix]

Sounds great! I'm wondering which IC you cannot find.

[Mihkel]

I would be happy to to add in Mouser part numbers and put together a Mouser Project/BoM for you. Cant promise it will be this weekend/next 24 hrs, but over the next week should be able to get it done. Probably my preferred route for most of the parts as it is a tax free way to get parts in to Europe (Sweden for me). If there is anything I cant decide about, I will leave it for others to help with.

In terms of group buy - sounds good if it is for the larger components.

Regards Timothy

I'm also working with BoM and doing the price comparisons. I'll add part numbers from Digi-Key, Mouser and also RS Components. To show best comparison I'll add all prices in same currency, € (without VAT). Unfortunately I have only few free hours per day, so think it will take one week or so, to get the list done. If I get it ready, I'll send the list to Prasimix for checking.

In terms of group buy, maybe I can help. I have worked with electronics for many decades and finding components and replacements is a part of my everyday's job and I can buy components with little discounts from some distributors. I also have (from earlier projects) many passive components already in my shelf, which I can share. So as I'm now working with the BoM anyway for finding best possible prices, I can also do the calculation for 10 sets for example to get the prices even better and share the information with you. I can't say any numbers yet, but I'm pretty sure that total cost of components for 10 sets will be much lower than for one set. In other words, you can buy only the components you need and don't have to spend extra money for buying left over components.

Please let me know, how many of you are interested in components group buy.
If there is interest at least for 10 sets, then I can buy the parts and send the sets to Prasimix.
I hope that he is not against that. He can then send the sets to you along with PCBs.

PS. This is not for making any business and get rich. I'm just trying to lower the cost of this great project for community, including myself.
Prasimix, Thank you again for sharing your project. You have done amazing work.

Cheers
Mihkel

[poorchava]

Mouser for one does not sell LT parts

Wys?ane z mojego HTC One M8s przy u?yciu Tapatalka

[VEGETA]

how much approximately can this be? If you wanna sell it, will it be reasonable to sell for 200$?

[prasimix]

how much approximately can this be? If you wanna sell it, will it be reasonable to sell for 200$?

Cannot be so low. Maybe if you have 1000 sets or heavily rely on eBay suppliers. In accordance to the current BOM one set is €287 (without enclosure and PCBs).

[prasimix]

If there is interest at least for 10 sets, then I can buy the parts and send the sets to Prasimix.
I hope that he is not against that. He can then send the sets to you along with PCBs.

I'm support this and other future initiative that makes this and similar open source project more affordable to the masses.

[VEGETA]

how much approximately can this be? If you wanna sell it, will it be reasonable to sell for 200$?

Cannot be so low. Maybe if you have 1000 sets or heavily rely on eBay suppliers. In accordance to the current BOM one set is €287 (without enclosure and PCBs).

Ok, but did you think about that before you designed it?

I mean will people really accept that price? what about the commercial ones?

[prasimix]

Dear VEGETA, this project is not about competing with closed/proprietary brands nor "amazing" and "spectacular" 10 bucks eBay solutions that provides in seller's wild dreams e.g. 200W output, ideal transient response, no ripple etc.

If money tag on something that draws your attention is only what drives you thru your life, than simply skip this thread (and this forum to some extent). Thousands of Euros is already spent in this project together with hundreds of working hours of two people to offer OPEN hardware and software solution for people that are sick of manufacturers that don't want to share product details with customers and when brutal hacking in hardware and firmware remains with previous removing of the "void warranty" sticker.

If you are interested please spent some time on our GitHub repository and try to place a price tag on e.g. firmware that is open, software simulator that allows you to test firmware even without having real device, etc. Then try to call e.g. Rigol or Keysight and ask them how much their firmware source code would cost you to get an idea how really expensive is this solution or how irresponsible I am when I dare to built such costly solution.

At the end you have in this thread a documented history of what I thought in the process, and here you can find some details about firmware that you for instance can regularly found in 10 bucks eBay power supplies (in wild dreams) .

[VEGETA]

Dear VEGETA, this project is not about competing with closed/proprietary brands nor "amazing" and "spectacular" 10 bucks eBay solutions that provides in seller's wild dreams e.g. 200W output, ideal transient response, no ripple etc.

If money tag on something that draws your attention is only what drives you thru your life, than simply skip this thread (and this forum to some extent). Thousands of Euros is already spent in this project together with hundreds of working hours of two people to offer OPEN hardware and software solution for people that are sick of manufacturers that don't want to share product details with customers and when brutal hacking in hardware and firmware remains with previous removing of the "void warranty" sticker.

If you are interested please spent some time on our GitHub repository and try to place a price tag on e.g. firmware that is open, software simulator that allows you to test firmware even without having real device, etc. Then try to call e.g. Rigol or Keysight and ask them how much their firmware source code would cost you to get an idea how really expensive is this solution or how irresponsible I am when I dare to built such costly solution.

At the end you have in this thread a documented history of what I thought in the process, and here you can find some details about firmware that you for instance can regularly found in 10 bucks eBay power supplies (in wild dreams) .

I am I really reading this? just OMG!

You fail miserably to understand the point! like... totally! I was not comparing this great work to a cheap ebay breakout board, and by no means use one of these! and I have never thought of buying firmware from Rigol or any other vendors (I don't know where you got the idea from).

I just ask about who are the target clients\customers\audience... that you are targeting with this design. I think it is really expensive, or at least not cheap or normal price for most people, and this was my concern. Don't try to label people badly like they are "driven by price tag in their life" or some other stuff because you don't know everyone and you don't live in a place where all people agree with you... which you or them can be wrong at any time.

Most open source designs are meant to be affordable to the users, this is the spirit of it by default. Of course you could build an expensive device for sure but most people when they read "open design" they would think it is "meant to be affordable"... I mean, like #1 requirement. Simply because there are tons of products that works perfectly out there so functionality is not the key factor. Take Dave's power supply design for example, it is very cheap and efficient enough right? maybe I compared this design to it somehow. I guess that uSupply will cost 100$ or so... but your supply will cost at least 400$ if you really want to sell it. And my question is that do you really accept that? maybe it is ok to you and you think it is a good idea... or maybe you don't care about if 10 people made it or 1000.

My question was very normal but you took it personal for some unknown reason.

Good job and keep doing what you think it is good.

[alexanderbrevig]

No one said open source has to be cheap or just good enough.
This project is more like https://www.apertus.org/ in that it tries to have a more no-compromise approach. For some, should be most, having access to - and control over - the firmware is worth very much.

prasimix did not make this for you or me, he probably made it for himself and his colleague. Then he is generous enough to let all of us benefit from all his hard work. Excellent

[VEGETA]

No one said open source has to be cheap or just good enough.
This project is more like https://www.apertus.org/ in that it tries to have a more no-compromise approach. For some, should be most, having access to - and control over - the firmware is worth very much.

prasimix did not make this for you or me, he probably made it for himself and his colleague. Then he is generous enough to let all of us benefit from all his hard work. Excellent

Actually, not quite. Open source by default is affordable, but as I said previously, it can be pricey. It is just the default of being cheap and publicly affordable. I repeat, I didn't say it "must" be.

Sharing designs is good but I don't know if it is good if no one will benefit from it or very minimal amount of people. It is the designer's choice after all and no one prevents him from sharing his expensive design. I just put a simple traditional (and very essential) question and got a tsundere response. That was not expect.

[kaevee]

No one said open source has to be cheap or just good enough.
This project is more like https://www.apertus.org/ in that it tries to have a more no-compromise approach. For some, should be most, having access to - and control over - the firmware is worth very much.

prasimix did not make this for you or me, he probably made it for himself and his colleague. Then he is generous enough to let all of us benefit from all his hard work. Excellent

Actually, not quite. Open source by default is affordable, but as I said previously, it can be pricey. It is just the default of being cheap and publicly affordable. I repeat, I didn't say it "must" be.

I have been using open source technologies in my day job since 1995. I have seen this misconception of open source is cheap. It is far away from truth. Total cost of ownership of solutions built around open source technologies is comparable to closed source / proprietary solutions. Open source can be cheaper if used in large volumes. For example, companies like Yahoo! (FreeBSD) and Google (Linux) have exploited the open source operating systems to their advantage. They have definite cost advantage as they run thousands of servers.

It holds true even for end user applications. For example, there is a cost associated to use OpenOffice/LibreOffice in the place of Microsoft Office even though it is a free download. Training people to use open source software will cost money and time.

Open source is all about freedom, missed by most people. Independent software vendors can no longer hold one hostage with closed source or proprietary solutions. Most open source licenses allow one to do whatever he/she wants as long as they don't try to convert it into a closed source solution. There are few licenses which allows one to convert into closed source solution if one acknowledges the original developer in their license. Apple's Mac OS X, based on Darwin is a great example. This freedom is not easy to come by and to be cherished and nurtured by all.

Venkat

[Strada916]

Look. Enough is enough. Lets all cool our heads. Calm down.

Can we please get back on topic here.

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[void_error]

Look. Enough is enough. Lets all cool our heads. Calm down.

Can we please get back on topic here.

Yeah, good idea.

[timgiles]

Updated BOM (I switched the two resistors in my version as well) with Mouser part numbers and link to Mouser Project uploaded to Github. I also corrected the link to TME in the readme.

Please note my message above, I have where ever possible selected the exact same component. I will (unless someone else wants to!) do a follow up that adds the 'cheapest acceptable' components as well. There are some high precision resistors where some might want to spend more to get higher precision and lower TC. So - please do not take this as a definitive Mouser list of components!

[timgiles]

For those interest: Missing ICs in Mouser

Analogue Devices ADG465
LTC 3864EMSE#PBF

[prasimix]

Hm, interesting. So neither Analog/LTC merge will not improve situation here . Anyway I added your changes into Master branch, made correction for wrong Farnell parts and refomat document that everything is easier for printing.