Author Topic: Power supply part 4  (Read 44259 times)

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Online Mechatrommer

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Re: Power supply part 4
« Reply #125 on: January 01, 2012, 04:44:57 pm »
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 :P ) my 2cnts.
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline JimmyM

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Re: Power supply part 4
« Reply #126 on: January 01, 2012, 07:12:31 pm »
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 :P ) 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.
 

Offline slateraptor

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Re: Power supply part 4
« Reply #127 on: January 01, 2012, 07:38:14 pm »
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*
 

Offline Nick Gammon

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Re: Power supply part 4
« Reply #128 on: January 01, 2012, 08:25:16 pm »
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/ArduinoISP

One 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.
« Last Edit: January 01, 2012, 09:00:31 pm by Nick Gammon »
 

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Re: Power supply part 4
« Reply #129 on: January 01, 2012, 09:54:19 pm »
Quote
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.
 

Offline Nick Gammon

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Re: Power supply part 4
« Reply #130 on: January 01, 2012, 10:05:49 pm »
That comment was dated October 03, 2010.

I tried recently (like a month or so ago) with my Uno without any problems.

More information here:

http://arduino.cc/forum/index.php?topic=82451.0
 

Online EEVblog

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Re: Power supply part 4
« Reply #131 on: January 01, 2012, 10:27:48 pm »
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.
« Last Edit: January 01, 2012, 10:33:53 pm by EEVblog »
 

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Re: Power supply part 4
« Reply #132 on: January 01, 2012, 10:29:55 pm »
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.
 

Offline JimmyM

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Re: Power supply part 4
« Reply #133 on: January 01, 2012, 11:49:29 pm »
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.
 

Offline RJSC

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Re: Power supply part 4
« Reply #134 on: January 02, 2012, 12:05:30 am »
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.
 

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Re: Power supply part 4
« Reply #135 on: January 02, 2012, 12:11:53 am »
Sure, you could scale it any way you like, 2.048A is just what I've chosen for my standard max range.

Dave.
 

Offline slateraptor

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Re: Power supply part 4
« Reply #136 on: January 02, 2012, 12:17:32 am »
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.
 

Offline Blue

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Re: Power supply part 4
« Reply #137 on: January 02, 2012, 02:44:03 am »
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
 

Offline joelby

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Re: Power supply part 4
« Reply #138 on: January 02, 2012, 03:10:44 am »
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?
 

Online EEVblog

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Re: Power supply part 4
« Reply #139 on: January 02, 2012, 04:38:18 am »
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.
 

Offline firewalker

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Re: Power supply part 4
« Reply #140 on: January 02, 2012, 10:30:24 am »
They already have plenty of videos available, I'm not going to help them out  ;)

I am guessing they are going to sue you because "You did it wrong".  :P :P :P

Or they could  appreciate it and renew you license. Trololololol.  ;D

Alexander.
Become a realist, stay a dreamer.

 

Offline Blue

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Re: Power supply part 4
« Reply #141 on: January 02, 2012, 11:22:41 am »
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
 

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Re: Power supply part 4
« Reply #142 on: January 02, 2012, 11:31:36 am »
I am guessing they are going to sue you because "You did it wrong".  :P :P :P

They already gave me a cease-and-desist on the use of altiumforum.com  ::)

Quote
Or they could  appreciate it and renew you license. Trololololol.  ;D

Hang on while I start up my flying pig  ;D

Dave.
 

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Re: Power supply part 4
« Reply #143 on: January 02, 2012, 11:34:32 am »
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.
 

Offline JimmyM

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Re: Power supply part 4
« Reply #144 on: January 02, 2012, 04:07:49 pm »
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.
 

Offline Greg J

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Re: Power supply part 4
« Reply #145 on: January 02, 2012, 05:41:50 pm »
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 ;) ;)
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Offline Nick Gammon

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Re: Power supply part 4
« Reply #146 on: January 03, 2012, 12:34:02 am »
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.
 

Offline benemorius

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Re: Power supply part 4
« Reply #147 on: January 03, 2012, 12:43:55 am »
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. ;)
 

Offline Blue

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Re: Power supply part 4
« Reply #148 on: January 03, 2012, 12:58:37 am »
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.


That would be wonderful  :)
 

Offline JimmyM

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Re: Power supply part 4
« Reply #149 on: January 03, 2012, 12:29:28 pm »
I haven't  watched it yet but the 5th video just finished uploading and looks promising if you're after a completed schematic. ;)
Where?
 


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