i hate to see this thread which shines as ee analog design to become a rather "code proned" or digital frantic thread. why dont we just wait for dave to finalize it and start modding from there? i trust digital side is not so dificcult for everybody (every idiot can count to 1
) my 2cnts.
i hate to see this thread which shines as ee analog design to become a rather "code proned" or digital frantic thread. why dont we just wait for dave to finalize it and start modding from there? i trust digital side is not so dificcult for everybody (every idiot can count to 1 ) my 2cnts.
Agreed.
I know this project is based on the LT3080, but LT also has the LT3083 (3A rated instead of the 1.1A of the LT3080). There shouldn't be any harm in substituting the higher current rated LT3083, right?
I was looking into using a slightly different pass element (discrete TO-3 and Op-Amp for greater power handling), then I came across the LT3083.
Sure, writing code for the arduino is C, but you have to write code for the arduino.
Only except that its c++. Yes, there's a difference.
(C++ is far superior, and safer of course).
*cough* Processing *cough*
The only difference is that anyone who wants to reprogram must have an ISP programmer of some kind instead of just straight USB. That's not a big deal I suspect.
Back onto the topic of Dave's gadget, there is a cheaper solution if you already have an Arduino. The Arduino development board itself (various flavours) can itself be used as an ISP programmer. There is a whole page devoted to this subject:
http://arduino.cc/en/Tutorial/ArduinoISPOne presumes that "the Arduino crowd" (as someone called them) would have an Arduino. So basically you just upload the "ISP sketch" to your Arduino, connect up 6 wires to the ICSP header of your target device (reset, power, Gnd, MISO, MOSI, SCK) and then upload your sketch in the usual way, telling the IDE that your "programmer" is the "Arduino as ISP".
So, a "free" programmer, if you need one.
The whole power supply project is a cool and educational idea. My next test is going to be to try to read back the voltage on the power supply using the analog input (ADC converter) on the Atmega, so that I could test if, when requesting 5V output, I actually get 5V. Presumably, once calibrated, this could be used to see if current limiting had kicked in. I'm guessing that Dave's design does just that, since there are lots of ports available on the processor chip for this sort of thing.
NOTE: Currently, you cannot use an Arduino Uno as an ISP programmer because the optiboot bootloader does not support this sketch. A revision for this is in progress.
I believe there's a workaround that can be found on the Arduino forum, but it's not (yet) mentioned in this tutorial.
I know this project is based on the LT3080, but LT also has the LT3083 (3A rated instead of the 1.1A of the LT3080). There shouldn't be any harm in substituting the higher current rated LT3083, right?
Correct.
The basic kit will likely ship with the LT3080, and those who want to upgrade the current can drop in the 3083.
But in my design the max current sense is 2.048A
And for those who complain about the price and availability, you can use an LM317 and live with the 1.25V minimum (just tweak the code to subtract it out).
Dave.
The whole power supply project is a cool and educational idea. My next test is going to be to try to read back the voltage on the power supply using the analog input (ADC converter) on the Atmega, so that I could test if, when requesting 5V output, I actually get 5V. Presumably, once calibrated, this could be used to see if current limiting had kicked in. I'm guessing that Dave's design does just that, since there are lots of ports available on the processor chip for this sort of thing.
Yes, it can even have two displays - set voltage/current, and actual voltage/current.
But I'm using external 12bit DAC and ADC.
Dave.
But in my design the max current sense is 2.048A
That's not too shabby either, but if the current sense resistance is halved, the current limit will be 4.096 A (resolved in 2 mA steps). Correct?
Then I would have to make a few tweaks to the code so that what's displayed on the LCD is what's happening in real life.
No, with a 12 bit DAC you should have 4096 steps (2^12), so you can have 4.096A with 1mA steps.
Maybe Dave's version has 0.5 mA steps.
Sure, you could scale it any way you like, 2.048A is just what I've chosen for my standard max range.
Dave.
But in my design the max current sense is 2.048A
That's not too shabby either, but if the current sense resistance is halved, the current limit will be 4.096 A (resolved in 2 mA steps). Correct?
Then I would have to make a few tweaks to the code so that what's displayed on the LCD is what's happening in real life.
With relatively high current draw, I suspect you're liable to encounter issues with thermal noise. 1 bit uncertainty on a 12-bit ADC is pretty ballsy as it is without paying extremely close attention to board layout.
Hi Dave,
In your previous thread part you mentioned that you used Altium for the pcb board design. Can you do a video about designing with Altium?
Thanks,
Cheers,
Nick
In your previous thread part you mentioned that you used Altium for the pcb board design. Can you do a video about designing with Altium?
Altium themselves have a large range of good videos covering most aspects of the software - is there anything in particular you were after that these don't go through?
In your previous thread part you mentioned that you used Altium for the pcb board design. Can you do a video about designing with Altium?
They already have plenty of videos available, I'm not going to help them out
Any PCB videos I do will be as package-agnostic as possible. Otherwise you aren't lerning PCB design, you are learning a drive a specific tool.
Dave.
Dave,
I really enjoyed one of your videoblog where you showed how to create a pcb (I forgot what numer is was).
What I accentually wanted is a videoblog showing you how to do the pcb layout for this project. Where to place components as you did with respect to noise etc.
Give some general idea's on how to layout a pcb - just as you did in your now famous document. I don't care if you do it with tool x, y or z.
Cheers,
Nick
I really enjoyed one of your videoblog where you showed how to create a pcb (I forgot what numer is was).
What I accentually wanted is a videoblog showing you how to do the pcb layout for this project. Where to place components as you did with respect to noise etc.
Give some general idea's on how to layout a pcb - just as you did in your now famous document. I don't care if you do it with tool x, y or z.
An entire multi-part PCB design tutorial video series is something I really want to, just needs some planing and time.
I was thinking I'd base it around my existing document as a starter.
For the PSU project I have a time-lapse video capture of me laying out the board, and I was going to do put some commentary on top of that (sped up of course).
Not ideal, but fairly easy to do.
Dave.
No, with a 12 bit DAC you should have 4096 steps (2^12), so you can have 4.096A with 1mA steps.
Maybe Dave's version has 0.5 mA steps.
Ah right. 4096. I can certainly live with 1mA steps.
Maybe as another part, or improvement you could show us how to design it into switching power supply ?
I mean, properly, not using one transistor
Sorry, the board is already done, DIP28 AVR.
This is an open source kit, so the idea is that people can build upon the existing code and share etc.
Dave, is the schematic available in any reasonably accessible form? (even just a screenshot in PNG format)
I still haven't resolved the issue of the current suddenly cutting out as you turn the pot down, and think maybe I didn't quite assemble my version to be the same as yours.
Sorry, the board is already done, DIP28 AVR.
This is an open source kit, so the idea is that people can build upon the existing code and share etc.
Dave, is the schematic available in any reasonably accessible form? (even just a screenshot in PNG format)
I still haven't resolved the issue of the current suddenly cutting out as you turn the pot down, and think maybe I didn't quite assemble my version to be the same as yours.
I haven't watched it yet but the 5th video just finished uploading and looks promising if you're after a completed schematic.