Talkback for article: 251, November2002

A Microcontroller based DC power supply

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From: gnoygnas <gnoygnas(at)> [ date: 2002-11-06 ]

What a incredible thing!
Even though I'm from Korea, I have learned English for 8 months and I don't understand all what you talked, I'm just interested in.

What does it use for? Can you control on Linux based?
I'm just wondering....

It is first time to write comments. ^^
I'm looking forward to receiving your answer.

Have a nice day...
From: Harinder <dhingra_h(at)> [ date: 2002-11-06 ]
Great. We need more articles like this.A good site of balancing hardware with software
From: guido [ date: 2003-01-11 ]
There is now a more abstract schmatic which shows how the
circuit works in principle:
From: wangqis <wangqis(at)> [ date: 2003-04-09 ]
Very nice,our begining'god
From: Honschu <chris_honschu(at)> [ date: 2003-05-16 ]
Great Project!

I have built 2 standard ones before. But your Schematic is the best!
Thanks !
From: qujinpeng <qujinpeng(at)> [ date: 2003-05-28 ]
I think the project is very perfect!
The Explaination is very detailed!Thanks!
From: Thomas <T..Baechle(at)> [ date: 2003-06-15 ]
First of all, I'd like to thank you for this great project.

I'm a total Newbie in microcontrollers and couldn't find the answer to my question in the datasheet, so I hope you can give me a little help. Is it possible to switch the push-buttons-lines by using optokopplers? Is the voltage between common_button_lines and push_buttons high enough for that?

Thanks in advance


From: guido socher <guido(at)> [ date: 2003-06-16 ]
Hello Thomas,
voltage levels are basically TTL compatible. You can use "optokopplers"
From: Christian <<c.kirschenlohr(at)>> [ date: 2003-10-15 ]
What about the costs of this Power supply? What are the totla costs for all parts in €? If its not so expensive, it could be a nice thing for electronic students...


From: suvit <suvit_0118(at)> [ date: 2003-11-14 ]
Dear guido

Regarding your letter, I am interested in testing project A Microcontroller based DC power supply from which is your task. However, I have some problems about the programme that is used to compile IC AT90S4433P so if you don’t mind, I would appreciate it if you would send me HEX.file In Thailand, we have less knowledge about microcontroller. I hope that your projects will help us to increase this knowledge in the future. Hoping to hear from you soon. Thanks for your help

Yours very sincerely



From: guido [ date: 2003-11-14 ]
Hi Suvit,
it is already included together with the source code.
The file is called: prebuildlinuxdcp_rom.hex
From: VIKRAM <vicky_raval2000(at)> [ date: 2004-01-07 ]
i want what is the whole programming software &how to install it.

From: lima <limalinmishra(at)> [ date: 2004-02-16 ]
more informations about microcontroller & microprocessor based systems.
From: nidhal <nid20032004(at)> [ date: 2004-03-15 ]
merci pour partager votre savoir avec nous,
c'est une formidable idée de commander une tension anlogique par un micro controlleur
nous ,en tunisie, on commence tout juste à etudier les micro controlleurs
mais je voulais savoir plus sur le fonctionnement des differents blocs de la partie commande
merci d'avance
From: nidhal <nid20032004(at)> [ date: 2004-04-23 ]
can any body give me a the hex files for a at90s8515 because we dont have the at90s4433
thank you..
From: Cao Jian <Caojian945(at)> [ date: 2004-04-25 ]
Excellent job.
You power supply is a good reference for my intelligent battery charger.
I am an EE student of BJUT(Beijing University of technology) in china. Pursuing my Bachelor degree...
From: Marian.S <kendallmarian(at)> [ date: 2004-05-21 ]
Hi Guido,
What a fantastic piece of work Master.
I have built the power supply and it works fine ,I have recompile the code follow your instructions step by step. I have u=30V I=3A.
Do you think that will be a chance of a digital multimeter control thru comms using an AVR in the far far away future?
Thank you for sharing the program and circuit schematics.
Keep up your good work.
God Bless you Guido

From: sergey bets <sergilyt(at)hotbox.RU> [ date: 2004-05-23 ]
Your power supply is very good,but microcontroller AT90S4433 no longer to produce. How to make this proect on ATmega8.Have you sourse code for Atmeg8.

Best regards
From: Rudi <rudi2005_2005(at)> [ date: 2005-11-13 ]

i am looking for a .hex file (prebuild code) to use this good power supply with 30 V and 3 Ampere.
Could somebody send me the source code and/or ready compiled .hex code for atmega 8 or at90s4433?

From: Dan Lenski <lenski(at)> [ date: 2005-11-29 ]
What an awesome project, Guido! Your description is impressively complete I've just gotten into uC's and would like to try building this, maybe over winter break.

One question: I am having a bit of trouble understanding the high-power portion of the circuit. As mentioned in the description, in order to produce a smooth DC output, it's necessary to add a low-pass filter to the output.

I can't figure out WHERE the low-pass filter is in the power circuit :-) I see that there's 10 uF in parallel with the output, and a .25 ohm resistor, but that would only give a low-pass cut-off frequency of f=60 kHz. Wouldn't that be too high to smooth out the corners in the PWM waveform?

Any enlightenment would be appreciated!
From: Guido [ date: 2005-11-29 ]
Hi everybody,
it is certainly possible to still build this power supply
however the design is almost 4 years old and avr-libc and the microcontroller
hardware has changed. The uC that I used here is no longer available
on the marked. You can still use the ideas and update the software for
a new microcontroller.
The best solution is however to just use the new power supply:
It's cheaper to build, has more features and is more modern.

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