Go Down

Topic: Variable Voltage Regulator (Read 2 times) previous topic - next topic

Paradigm

Hi All,

          I need to control a dimmable e-ballast with a voltage varying from 0 - 10VDC using an Arduino Uno. My Uno is connected to Xbee and therefore can be control wirelessly. The voltage will vary depends on the control input from the xbee and therefore lights will turn ON/OFF and dim accordingly.

         Currently I am using KA317 with a AD5290 to vary the resistance at the ADJ pin of the KA317. However the limitation to this method is that the KA317 cannot go below 2V which means that my dimmable e-ballast cannot switch off totally.

         I am checking whether anyone had any idea of any SOC voltage regulator that can be connected to Arduino digital pins, I2C or SPI to vary the voltage from 0 to 10VDC?

         Thanks a lot

oric_dan

Actually, I think LM317 type v.regs can go as low as 1.2V, with the reference pin grounded.
If you want lower, try putting a 1N400x diode in series with the Vout pin.

be80be

Dropping the voltage to turn off doesn't look like the best way. If your dimming
looks good. I would use a extra pin to shut the power off with a power MOSFETs

Paradigm

Hi Thanks for the reply,

             Will put an SSR to turn ON/OFF the live to dimmable ballast. But is there a chip that can do the voltage regulation from 0V to 10V or 1.2V to 10V interfacing with a UNO straight?

winner10920

You can use pwm , a npn transistor and a low pass filter to directly get0-10v

Paradigm

Hi all, any other option? Is there really a chip that does the job? Just curious and wanna find out

Osgeld

winner10920 already told you the best way, is there a chip? maybe ... but its not going to get any easier than using the analog out function of the arduino to tickle a transistor and smoothing the output with a fat cap
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

winner10920

There's. A formula and many calculators online too that will tell you the ripple and response time of any RC lowpass filter at a particular frequency, less ripple makes it less responsive and vice versa

dc42

Personally I'd use an R-C filter on one of the PWM pins followed by an op-amp to double the voltage. However, if the input resistance of the device you are driving with 0-10V is high enough, then you can use an NPN transistor followed by the R-C filter, as has already been suggested.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

dhenry

Quote
I2C or SPI to vary the voltage from 0 to 10VDC?


Unless you tie the other end of the pot to a negative voltage source.

Krupski


Actually, I think LM317 type v.regs can go as low as 1.2V, with the reference pin grounded.
If you want lower, try putting a 1N400x diode in series with the Vout pin.


If you connect the reference (the resistor that goes between Vout and Adj) to the "output" end of the diode, the 317 will regulate out the diode drop and still give you minimum 1.2v.

If you connect the reference BEFORE the diode, you will get approximately 1.2-0.7 volts minimum out, but the regulation will be poor due to the variance in forward drop of the diode at different currents.
Gentlemen may prefer Blondes, but Real Men prefer Redheads!

retrolefty


Hi all, any other option? Is there really a chip that does the job? Just curious and wanna find out



http://www.avdweb.nl/arduino/hardware-interfacing/simple-10-bit-dac.html


Lefty

Paradigm

Hi Winner, Osgeld & dc42,

                     Do you have the connection schematic to share? So that I can try connecting and test on my e-ballast. Do I need 12V and 5VDC supply also? Thanks a lot

winner10920

I can't give you a shematic, right now anyway I'm on my phone, but yes a 10-12v supply would be neccesary although you could probably get away with a small booster circuit if the input impedance of the ballast is small
But the circuit will be a simple transistor switching the 10v supply and passing that thru a lowpass filter

dc42

The op amp solution needs a 12V supply. Is that a problem? If so, and the input resistance of the device is high enough, then you could instead use a small audio transformer to step up the PWM output to 10V. Post a link to the device you want to control.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

Go Up
 

Quick Reply

With Quick-Reply you can write a post when viewing a topic without loading a new page. You can still use bulletin board code and smileys as you would in a normal post.

Warning: this topic has not been posted in for at least 120 days.
Unless you're sure you want to reply, please consider starting a new topic.

Note: this post will not display until it's been approved by a moderator.
Name:
Email:

shortcuts: alt+s submit/post or alt+p preview