Funny how you consider THT more DIY friendly than SMT when I think the exact opposite. There is no need to flip flop the board which I find tedious when doing THT and I personally find soldering 0603 easier than THT. Also, I don't think that there was mention about tolerance of used components? ('Normal' THT resistors are 5%, 'normal' SMD are 1%.)
Ha, when I started this project I had zero experience with SMT. With simple lamp magnifier (x3, x8) it started to be a really joyful experience. Personally I can say that I'm now ready for "SMT only" solution even without stencils and oven
As you can see there is a just a few responses to this project and I'd like to receive more feedback what to use for the "final" PCB revision.
Kudos for modular design. That is really interesting. It got me thinking thought with connection to chain-ability / is there anything stopping to put together more than two power stages? Not that I would need more that 100 volts but sometimes (for motor control applications or electrolysis) I need more that 6A (10A would be nice). So far I was using power supply with few discrete output voltages but something more continuous would be better (for example for DIY thought hole copper plating where you need to control current based on area of the board).
5A per module shouldn't be a problem and I already made some testing with CC loop disconnected.
I set limit to 2 modules due to MCU board and BP post board, but of course with bigger MCU then currently selected Atmel32u4 (for more I/O pins) hopefully that is achievable.
What kind of toroidal transformer are you using? With your requirement of no fan (no noise) I would assume some lower core gain type (usually sold as AUDIO) to minimalize risk of rustling which is sometimes a big problem (and quite annoying).
I'm currently using a custom made by local manufacturer but, I hope that something like this
Breve Tufvassons TTS300/Z230/48-48V or this one
Talema 55188-P1S2 will be fine. Another possible source (that also included audio grade shuff) with quite attractive prices is
Toroidy.pl. Please note that I currently have no experience with any of mentioned products.
It's quite interesting that you would make analog only capability one of requirements of the design. I can understand the theoretical mental exercise of it but really who would in today's age lab power supply without MCU. Moreover one with quite complicated design and some serious high quality requirements. The design then has to accommodate two ways for controlling voltage and current. Rails on PCB are longer and there is bigger room for interference and error. (At least the lab PSU I have seen up until now usually had some form of shielding of control signal to DAC/ADC. But on other hand you are only shooting for 1 cV/cA and these had 1 mV/mA accuracy so maybe that is OK.)
I think that possibility to have functional unit without coping in the first step with digital part is beneficial for general DIY audience. That together with modular design simplify testing and more gradual approach to the final product. It's not even real (or serious) analog only approach since at least tracking for dual channels is not implemented.
BTW, ADC/DAC control traces on the power PCB is really short and hopefully it will not picking up substantial noise.
Interesting at your choice to add ethernet connection. That is quite industrial. Small note on your panel design. I don't remember when I lastly disconnected ethernet connection on one of my devices. It usually stay connected all the time (non portable devices), but I usually disconnect USB after use. So ergonomically I see the point to have USB connector on front panel, I don't see the point in ethernet's case, quite the opposite.
Yes, I put as much as possible features on the MCU as an exercise
We'll see to which extent it will works. I'm agree with you about ethernet and USB. Need some rethinking and possibly USB connector could be something like this
USB 2.0 B female panel mount to 5Pin F 0.1" header and small "breakout" PCB for ethernet has to go on the rear panel.
I have never had in my hands that display or at least I'm not aware of it. But at that photo it looks positively horrible. I hope that it is only bad photo-effect. (But then it's arduino everybody's dog can change it.)
Huh, it doesn't looks so horrible and it's really
cheap . Anyway as you can see a
DOGL128 is also supported by MCU board.
You have the ADS1120 in your schematics as 15-bit, but by the TI it's 16-bit.
Yes, but bipolar, for unipolar you can use only 15 bit.
Do you have plans for some form of distribution? I have seen the OSHW logos on boards but then they are 110x60 mm. Given that Chinese fab houses work with discrete sizes it will get pretty inefficient pretty quick. So if there was way to buy set of PCBs it would be great.
My idea is to publish Eagle and Gerber files of first workable version. Thanks to modular approach that can be done in more steps (i.e. various pre-regulators, post-regulator, MCU board etc.). I can also organize group buy of PCB only (I closed one successfully last year on diyaudio forum) if such thing is not against policy of this forum.
On the same note: Are the boards from Printed.CZ not tinned? Looks like it.
This one is not since I asked for "galvanic Au" surface instead. You can play with different versions on their
online calculator.
Do you plan on some protection for cases when for some reason there is problem in connection of the boards?
What kind of connection problem you have on your mind?
Well I hope I didn't make complete ass of myself.
Not at all
. I believe that people is here to share some ideas and assist each other not to compete who is the smartest (anyway even the most brilliant mind for electronic could still be a complete 'life idiot' so what at the end could be a "RMS value" of such person?
).