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1  International / Le bar / Re: pas onereuse la souris on: October 06, 2012, 02:54:08 pm
MS-DOS 3.21 ???

Hmmm, 1988?
2  Using Arduino / Motors, Mechanics, and Power / Re: Using an ATX power supply on: August 25, 2012, 09:02:39 am
.... What is your goal? A power supply for your projects that will be reliable and accurate, and safe; or is it to learn how power supplies work and how to build them?

You made the point: For sure it's more expensive (mainly if you calculate the time) to build it yourself (but
don't tell it my wife, please smiley-cool), and you end up with something not so performant than the same thing out of the box, but the reason why I'm playing with the Arduino is that I love the learning effect, and I have to admit that most of my projects becomes boring, just when they are finished.    The journey is the reward.

3  Using Arduino / Motors, Mechanics, and Power / Re: Using an ATX power supply on: August 24, 2012, 06:17:26 am

Yeah, but this is giving exactly what you should avoid: no current limitation, and with this you will produce (for sure) a lot of magic blue smoke  smiley-roll

Problem is that the PSU is able to deliver huge amount of current (> 30A on 5V). Imagine you have a short on your test circuit....... Better is to limit the current, or at least integrate fuses (but this was too expensive for me, considering the number of shortages I produce per day in average smiley-evil ).

4  Using Arduino / Motors, Mechanics, and Power / Re: Using an ATX power supply on: August 23, 2012, 12:10:18 pm

and here now the code I've used. Nothing special, just the code to put the limits either directly (UCC2915DP) or via digital pot (MAX890L). On top the sensing of the current via the LT6106 on Analog 0-2.

For sure no great art, but as I learnt by doing I have sometimes strange ways to reach the target smiley-roll.

Please free to comment.


5  International / Français / Re: Arduino les Pins (analog/Digital pas le camping) on: August 22, 2012, 03:14:15 pm
Tu peut connecter tous les buttons a un seule Pin analog.


6  Using Arduino / Motors, Mechanics, and Power / Re: Using an ATX power supply on: August 22, 2012, 01:43:54 pm

Very cool Jens, I would be very interestedin the circuit and code.


Here the circuit (hope it's readable).  The code I have to clean before sending it out. Hopefully I will find the time tomorrow, if not you have to wait till this week end.


7  Using Arduino / Motors, Mechanics, and Power / Re: Using an ATX power supply on: August 22, 2012, 12:00:30 pm
I was looking for a bench PSU, but was surprised by the prices of these boxes, and also because I'm a Arduino freak (even if beginner) I decided to build my own.

In order to overcome the missing current limitation, I've build a current limiter for the three voltages (3.3V, 5V and 12V) with MAX890L (for 3.3V and 5V) and UCC2915DP (for the 12V) Current Limited High Side Switches. These are Switches which are switching off, if a programmable current is reached or exceeded. All this driven by a ATmega328 programmed with Arduino, what else smiley-cool?

All this integrated in the PSU, with LCD screen showing the limitation for the 3 voltages, and the actual current.

It's working correctly, only problem is that I have probably un unstable tension in my circuit, so the current measurement is not really acurate, but for what I need (eliminating the risk of smoke) it's fine. One day, when I do not have other projects running, I will refine it, but for the time being it's fine for me.

If somebody is interessted, I can post the circuit, code of the PSU.

I attached a photo of it (the led's are "dimmed" with tape for the photo only)


8  International / Français / Re: quelle différence entre les 2 atmega328 ? on: April 19, 2012, 12:11:32 pm
Mais attention: la signature des ces deux chips est différente:

0x1e 0x95 0x14 pour le 328 et
0x1e 0x95 0x0f pour le 328P.

Pour charger le bootloader on doit trafiquer un peu dans les fichiers d'Arduino "Board.txt" et "AVRDude.conf".

Voir,100511.0/topicseen.html pour les details.

Une fois le bootloader sur le chip, le comportement est identique (sauf le PicoPower).

9  International / Le bar / Re: Presentez vous on: March 30, 2012, 06:34:32 am

Je m'appelle Jens, je suis Allemand (veuillez excuser mon français… smiley-cool) vie a Grenoble, travaille dans la Loire, 50 ans (depuis peu) mais toujours jeune, marié depuis 23 ans, et toujours amoureux), deux enfants, un fox terrier, un chat.

J'ai fait un apprentissage de 3,5 ans d’Outilleur en Allemagne (Hambourg), et un jour mon boss ma demander d’aller dans notre société en France, pour la réorganiser. Mon argument que je connaissais pas un seul mot de français était rejeté avec la phrase : « Pas grave, il y a des cours de français ! ».

« Pour 1 an, maximum 2 », et ça fait maintenant 25 ans (avec interruption dans d’autre pays) que ça dure…. Entre temps je suis le directeur de cette PME de découpage de haute précision pour l’électronique. (Non, les PDIP28 pour les ATmega 328 ne sont pas produit chez nous en France mais par mes collègues en Chine, mais sinon on fabrique une grosse partie des leadframes encore utilisé en Europe (ST, Infineon, Epcos, Micronas, Vishay, Zetex, etc…), ca. 1,5-2 Mrd de pcs par an).

 Malgré que je travail pour et avec les grandes du semi-conducteur depuis plus que 30 ans, je joue avec l’électronique seulement depuis un an, quand j’ai cherché à bricoler un déclencheur pour mon appareil photo pour faire des photos des goutes d’eau, et voila, je suis tombé sur l’Arduino, que j’adore, pour sa simplicité, pour le concept et la philosophie qui est derrière.

Actuellement je « travail » sur une alimentation de labo (vieux alim d’ordinateur, avec limitateur de courant réglable pour 3.3V, 5V et 12V), un réveil programmable avec trois alarmes différentes programmable pour chaque jour de la semaine) et un contrôleur automatique à monter derrière les presses.

Mon approche est toujours le même : d’abord le prototype avec l’Arduino, et quand ça marche à peu prés, je réalise le projet en stand-alone.
10  International / Deutsch / Re: Timer mit Mega8? on: December 07, 2011, 04:00:51 am
Hi Tobias,

Ich kann dir leider keine Antwort auf die Frage bezüglich der Register geben, aber ein möglicher Workaround wäre die lib "SimpleTimer", die allerdings nicht mit interrupts arbeitet, sondern mit der millis() Funktion.

Ich habe gerade ein Projekt für nen Mega8 mit dieser lib fertiggestellt, und es läuft ohne Probleme.


11  Using Arduino / Installation & Troubleshooting / Re: Issue with Arduino 1.0 on: December 01, 2011, 02:00:27 pm
Ok, found the reason and the solution in this article: Arduino 1.0 is Out: Here’s What You Need To Know:

The library has to be changed. Changes done, and: WOW!!! it's running  smiley smiley-cool smiley-yell smiley-mr-green smiley-grin smiley-lol

This above mentioned article is an absolutly must if you want to migrate to Arduino 1.0 and if you are working with a lot of Libraries.

12  Using Arduino / Installation & Troubleshooting / Issue with Arduino 1.0 on: December 01, 2011, 12:09:39 pm

just downloaded and installed Arduino 1.0 and are now running in strange problems with my actual project: There seems to be a problem with the library "shiftreglcd". When verifying I get the following error message:

In file included from Fototrigger26.cpp:17:
H:\Arduino\meine Schaltungen\libraries\ShiftRegLCD/ShiftRegLCD.h:76: error: conflicting return type specified for 'virtual void ShiftRegLCD::write(uint8_t)'
F:\Arduino\arduino-1.0\hardware\arduino\cores\arduino/Print.h:48: error:   overriding 'virtual size_t Print::write(uint8_t)'

With Arduino 0.22 and 0.23 it works without problems.

Anybody an idea?


13  Using Arduino / General Electronics / Re: Need help regarding kick back diode on: November 20, 2011, 06:58:07 am

  Max value of resistor = (((Vds voltage rating of mosfet)/(relay supply voltage)) - 1) * (resistance of relay coil)

The higher the resistor, the faster the release time. Do the above calculation, for the highest relay supply voltage you are likely to get in your circuit, and using the resistance of the relay coil you measure when it is cold. Then use a value a bit lower than calculated to allow some margin.


Perfect. With this formula I can finally calculate the resistor to be used. Will give it a trial with some 10 - 20% margin.

Max value = ((200V / 18V) -1 ) * 72 Ohm = 730 Ohm. Will start with a value around 560 Ohm.

A Zener diode is in theory faster, but if you have a 100v mosfet then you would need an 80v Zener diode, which will be hard to find.

The mosfet is rated with 200V, so a zener with a value of 130 V should be fine (130V is the higest value I found in the cataloque of my supplier)

It may even be safe to omit the kick back diode completely and allow the energy to be absorbed as avalanche energy in the mosfet (effectively, the mosfet itself behaves like a Zener diode), however to know whether this is safe you would need to know the amount of stored energy that is released when the relay opens. [You could use the Arduino to measure this.]

Can you give me a hint how to measure this energy?

However, if you're trying to do water drop photographs, then mechanical relays may be too slow for what you want anyway.

As explained above: The coils we are talking about are the coils from the solenoids which are actioning the valves for the drops. The camera itself and the falshes are connected via optocoppler to the µcontroller.

Thanks a lot for this lesson.


14  Using Arduino / General Electronics / Re: Need help regarding kick back diode on: November 20, 2011, 05:07:02 am

Waouh! I'm impressed. I was hoping to get an answer for my question, and what I finally got is a lesson in electronics. Thanks guys, your implication is really great.

I will try to get now a zener diode 18V to do some tests, and check whether I can see a change to the todays performance.

So....if you have an IRF610 rated for 200V, that's not going to be a problem (MOSFET breakdown voltage). I'd worry more about the breakdown voltage of your relay coils. If you can't find that specification I'd say a safe number is the voltage rating of the coil itself under normal operation (18VDC). If you add a 12V-18V zener diode I think you will have a good result.

All datas regarding the electrical parameters which I have are the following:
Voltage: 12V DC
Wattage: 2W

Is it possible to calculate better the best value for the Zener?


A simple low value resistor, say 10 ohms or less will probably be sufficient to minimise hold-up time, but it will be a balance between decay time versus back emf.


I will give this one also a trial. Advantage: Probably I have some resistors in the range of 10 Ohms available. Will give it a trial next week end.

The slowing of the release is small compared with the over all slowness of using a mechanical relay. It is not something that is significant in the context of what the OP is worrying about.

Possible, problem is that till  now I didn't found any clear indication of the time for the fall back due to the diode. Taking into consideration that my opening time for the waterdrop solenoid is only 5 ms, I can imagine that even a small increase of fall back time might have a negative impact. But as mentioned before: I do not know nothing, I'm only looking for potential negative impacts.

Once again, thanks a lot for your help.


15  Using Arduino / General Electronics / Need help regarding kick back diode on: November 19, 2011, 01:32:19 pm

I need some help, as a complete newbee in electronics, I'm only starting to learn the basics by doing (and reading a lot):

I have build a stand alone box in order to trigger my camera by sound, lightining, time, etc, and I also integrated some handling of relays for water drop photographie. In principle it's running (and I've got the first nice pictures), but now I have one question which came up when I read an article regarding kick back diodes:

I have integrated the possibilities to handle 4 relays. These are driven via PhotoMOS (AQW225) in order to protect my ATmega328. These PhotoMOS are driving a MOSFET (IRF610) cause the PhotoMOS does not have enough power to drive the solenoids (nominal 12V DC, I'm driving them with 18V DC) directly. In order to eliminate the kick back effect coming from the solenoid I added a diode (1N4002) reverse-biased between the two connections of the coil. So far, so good. It's working (as far as I can judge: no smoke, no strange smell, and the drops are falling).

Now I have read a good article regarding kick back diodes, in which is written that this kick back diode is eliminating the inductive kickback (fine till here all is ok with me), but is also slowing down the realease time of the coil, which might have a negative impact on my configuration, as my coil is activated in the range of a few ms.

In the same article is written, one can speed up the release time by adding a resistor in serie to the diode. My problem is that I have no clue (and here the article didn't help me) how to calculate this resistor. And due to the fact that I cannot measure this time, I have no possibility to go via trial and error.

Can anybody help me on this, please. Via google I found also that with a Schottky diode one can speed up this process, or even with a Zener diode. But here again: which one will be the right one, what are the parameters to calculate the values. Questions over questions.

Thanks a lot.

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