5 ms·

Cool article! Where did you learn PSU design? Are you "classically" trained or self taught? edit: The article on the design of the PSU is also great: https://t

by tinco 2y ago

Cool article! Where did you learn PSU design? Are you "classically" trained or self taught? edit: The article on the design of the PSU is also great: https://tomscii.sig7.se/2024/04/300W-Linear-DualTracking-Lab-PSU https://tomscii.sig7.se/2024/04/300W-Linear-DualTracking-Lab...

pjc50 2y ago
Author is fairly early on in the self-taught stage from this sentence: "(I really need to start digging into chapter 5 of The Art of Electronics, which is about achieving precision in electronic circuits)." The author is aware of their learning-by-doing process, which is pedagogically great, but does mean they have to slog through finding things out the hard way. "I really need to ditch the TL074" - yes, it's from 1979. You'd also benefit from moving away from complicated analogue arithmetic and just buying a better ADC; remember that "losing half the range" is only one bit! You can buy some more bits at the bit store! (well, up to about 24, but then things have already got hairy in the analogue front end at that point) The word "bandwidth" does not appear in this article, which means the author has not yet encountered control theory and is therefore not aware of a whole range of possible ways for a PSU to suck. They would benefit from reading App Note 47. In fact, anyone working with op-amps would benefit from reading App Note 47, from the late great Jim Williams. https://www.analog.com/media/en/technical-documentation/application-notes/an47fa.pdf https://www.analog.com/media/en/technical-documentation/appl...
- camtarn 2y ago
  This is excellent. "Like all engineering endeavors, high speed circuits can only work if negotiated compromises with nature are arranged. Ignorance of, or contempt for, physical law is a direct route to frustration. Mother Nature laughs at dilettantism and crushes arrogance without even knowing she did it."
- user_7832 2y ago
  Your comment is solid in terms of how deep any field goes... and is also a good motivation for me to not bother with DIY power supplies :) (Don't worry I anyway wasn't planning to mess with mains voltages, only 12-24V)
  - exmadscientist 2y ago
    Power supplies are really interesting in that regard, because they're both (1) one of the best ways to learn as a beginner or intermediate beginner and (2) one of the worst value/$ ways to learn. There are so many decent power supplies out there to buy that I think building your own is not really the right choice, unless you see yourself doing more offline power or even high-power (audio?) amplifiers in the future.
    - user_7832 2y ago
      > high-power (audio?) amplifiers Coincidentally I am interested in that field in the future. Though I'm fairly sure that there are good quality existing designs on github/diyaudio.com, so I likely don't need to design one myself. Would you have any other suggestions for this topic/field?
      - pjc50 2y ago
        > Would you have any other suggestions for this topic/field? Acquire a scope as soon as possible. Doesn't have to be good, expensive, or even digital, but without one you literally cannot see what you are doing. You can emulate this with PC interfaces, but it's so much more convenient as a separate bench instrument. Decide how much of a traditionalist you are. Class D has overwhelmingly won in terms of sound quality, convenience and efficiency, but if you want to build a valve amp and warm your hands around the glow, that's a very pleasant hobby.
        user_7832 2y ago
        Thanks a lot! I definitely plan to get an oscilloscope when I start building. In terms of classes I'm still not sure, but I'll likely go for a multi-channel/amp setup with DSP, perhaps some frequencies Class A & some D. I'll probably first experiment and listen to see what I like when I get started.
  - creer 2y ago
    Depends on the objective. In some cases, slapping together a few components is fine and straightforward. In particular if you pay attention to how other people are using them - perhaps pay attention to the provided standard schematic and layout in the spec or application note - and if you are well within the expected use for these components. Notice magazine articles. Use several sources. Something might still go wrong, but then you might also buy the wrong widget from the wrong seller... If you are deliberately striving to push the limits one way or the other, then yeah, you will run into the exact reasons nobody else did it.
- marcosdumay 2y ago
  > You can buy some more bits at the bit store! (well, up to about 24... Most of the world really can not. It can only get up to 16, and that's with shady suppliers thanks to China ignoring international law.
  - stephen_g 2y ago
    What is this meant to mean? There are plenty of 24- (and more) bit DACs available to ship world-wide on Digi-Key, Mouser etc... There are some US export controls on DACs that have high bit-rates and high output rates (mostly over 3500 MSPS) which is far in excess of what you'd need for most things. And US export controls aren't 'international law'...
  - pjc50 2y ago
    I happen to work at the "more bits" store: https://cirrus.com/products/cs5302p/ https://cirrus.com/products/cs5302p/ (ok, "32 bits" and "126db" aren't quite the same, but those who need to know understand the difference and why the extra bits are still useful)
dfox 2y ago
Note that the PSU is not really a tracking one as it can providde different positive and negative voltages in CC mode. True tracking bipolar PSUs do not do that (which is the point why they exist, otherwise you could just connect two PSUs in series).

by tinco 2y ago

pjc50 2y ago

Author is fairly early on in the self-taught stage from this sentence: "(I really need to start digging into chapter 5 of The Art of Electronics, which is about achieving precision in electronic circuits)." The author is aware of their learning-by-doing process, which is pedagogically great, but does mean they have to slog through finding things out the hard way. "I really need to ditch the TL074" - yes, it's from 1979. You'd also benefit from moving away from complicated analogue arithmetic and just buying a better ADC; remember that "losing half the range" is only one bit! You can buy some more bits at the bit store! (well, up to about 24, but then things have already got hairy in the analogue front end at that point) The word "bandwidth" does not appear in this article, which means the author has not yet encountered control theory and is therefore not aware of a whole range of possible ways for a PSU to suck. They would benefit from reading App Note 47. In fact, anyone working with op-amps would benefit from reading App Note 47, from the late great Jim Williams. https://www.analog.com/media/en/technical-documentation/application-notes/an47fa.pdf https://www.analog.com/media/en/technical-documentation/appl...

camtarn 2y ago
This is excellent. "Like all engineering endeavors, high speed circuits can only work if negotiated compromises with nature are arranged. Ignorance of, or contempt for, physical law is a direct route to frustration. Mother Nature laughs at dilettantism and crushes arrogance without even knowing she did it."
user_7832 2y ago
Your comment is solid in terms of how deep any field goes... and is also a good motivation for me to not bother with DIY power supplies :) (Don't worry I anyway wasn't planning to mess with mains voltages, only 12-24V)
- exmadscientist 2y ago
  Power supplies are really interesting in that regard, because they're both (1) one of the best ways to learn as a beginner or intermediate beginner and (2) one of the worst value/$ ways to learn. There are so many decent power supplies out there to buy that I think building your own is not really the right choice, unless you see yourself doing more offline power or even high-power (audio?) amplifiers in the future.
  - user_7832 2y ago
    > high-power (audio?) amplifiers Coincidentally I am interested in that field in the future. Though I'm fairly sure that there are good quality existing designs on github/diyaudio.com, so I likely don't need to design one myself. Would you have any other suggestions for this topic/field?
    - pjc50 2y ago
      > Would you have any other suggestions for this topic/field? Acquire a scope as soon as possible. Doesn't have to be good, expensive, or even digital, but without one you literally cannot see what you are doing. You can emulate this with PC interfaces, but it's so much more convenient as a separate bench instrument. Decide how much of a traditionalist you are. Class D has overwhelmingly won in terms of sound quality, convenience and efficiency, but if you want to build a valve amp and warm your hands around the glow, that's a very pleasant hobby.
      - user_7832 2y ago
        Thanks a lot! I definitely plan to get an oscilloscope when I start building. In terms of classes I'm still not sure, but I'll likely go for a multi-channel/amp setup with DSP, perhaps some frequencies Class A & some D. I'll probably first experiment and listen to see what I like when I get started.
- creer 2y ago
  Depends on the objective. In some cases, slapping together a few components is fine and straightforward. In particular if you pay attention to how other people are using them - perhaps pay attention to the provided standard schematic and layout in the spec or application note - and if you are well within the expected use for these components. Notice magazine articles. Use several sources. Something might still go wrong, but then you might also buy the wrong widget from the wrong seller... If you are deliberately striving to push the limits one way or the other, then yeah, you will run into the exact reasons nobody else did it.
marcosdumay 2y ago
> You can buy some more bits at the bit store! (well, up to about 24... Most of the world really can not. It can only get up to 16, and that's with shady suppliers thanks to China ignoring international law.
- stephen_g 2y ago
  What is this meant to mean? There are plenty of 24- (and more) bit DACs available to ship world-wide on Digi-Key, Mouser etc... There are some US export controls on DACs that have high bit-rates and high output rates (mostly over 3500 MSPS) which is far in excess of what you'd need for most things. And US export controls aren't 'international law'...
- pjc50 2y ago
  I happen to work at the "more bits" store: https://cirrus.com/products/cs5302p/ https://cirrus.com/products/cs5302p/ (ok, "32 bits" and "126db" aren't quite the same, but those who need to know understand the difference and why the extra bits are still useful)

dfox 2y ago

Note that the PSU is not really a tracking one as it can providde different positive and negative voltages in CC mode. True tracking bipolar PSUs do not do that (which is the point why they exist, otherwise you could just connect two PSUs in series).