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Author Topic: Dimmer controller for high frequency fluorescent tubes  (Read 907 times)
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Helsinki
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Hi everybody!

This is my first post here and I'm looking for some input whether my idea is possible, or a good or bad one, with Arduino. I haven't done much research yet, but I'd like to hear some comments from experienced guys. My project is this:

I bought four 3500 lumen high frequency full spectrum fluorescent tubes to fight the dark winters here up north in Helsinki. My plan is to build an "artificial sun" from them - that's 14000 lumen total smiley I also bought control gear (ballasts) to drive them. The controller supports analog 1-10 V control voltage to dim the lights, plus there's a switch input to completely shut the lights off. I'm planning on installing a regular 1-10V dimmer first, but it crossed my mind that I might be able to add some nice control logic there to turn on the light slowly in the morning - to simulate sunrise at 6-7 a.m. perhaps. Plus, I might be able to control it wirelessly. Dim it down in the evening, turn it off for the night and have it light up again in the morning automatically.

This is what the controller wiring diagram looks like, i've got two pieces of that number two in the image:



So, I think I need to drive two relays to isolate the mains current for driving the switch controls, to shut the individual ballasts on and off. I also need a 1-10 V DC control voltage for the dimming function for both of them  - thats "<1mA" according to the doc.

Do you think it would make sense to do this with Arduino? Is there a DAC on any of the boards? Or can somebody recommend something suitable for the control voltage?

I'm thinking of putting both the ballasts in one box which is separate from the lamp itself, because the sales guy said the ballasts last longer if they are not exposed to the 60-70 degrees centigrade the tubes produce. I could probably mount the Arduino board in the same box.

What about the power feed to the Arduino board? Is there a recommended transformer from 230 V AC that could be mounted in the same chassis perhaps?

I could also add the Ethernet shield/WiFi shield to get network connectivity for controlling it from my computer. I'd also need a separate remote control (bluetooth, perhaps?) and a "manual override" switch plus potentiometer or something like that in case I can't use my computer or the remote control.

Any tips, ideas and links would be very much appreciated!

P.s. If you are interested:
- The tubes are 54 W T5 Viva-Lites with G5 socket : http://www.viva-lite.us/full-spectrum-daylight-tubes-t5.html
- The ballasts are Helvar EL2x54sc dimmable: http://www.helvar.com/sites/default/files/product_datasheets/EL-sc_T5_datasheet_EN.pdf

This is what the Helvar documentation says about the switch:
"Suitable switch:
• Automatic return type. Mains rated (Mains is still present at the ballast
terminals if the lamps are switched off from Switch-Control).
• The switch should withstand a short circuit current of:
- 0.2 mA per ballast"

So mains rated relay should do the job, don't you think?



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It is possible if all you need to do is vary the analog signal, however, the arduino outputs 0-5V not 0-10V, SO you will need a amplifying circuit. Actually a simple 0-10V OP amp should work, or if you want to control multiple ones in the future, then a H-bridge will work too.

If it is really cold there, then you may want to get a insulated box to put all this in, if you haven't already.
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Helsinki
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It is possible if all you need to do is vary the analog signal, however, the arduino outputs 0-5V not 0-10V, SO you will need a amplifying circuit. Actually a simple 0-10V OP amp should work, or if you want to control multiple ones in the future, then a H-bridge will work too.

If it is really cold there, then you may want to get a insulated box to put all this in, if you haven't already.

Ok so I need an op amp that I could hook up to the same power supply as the Arduino board, get the 0-5 out of the board and amp it up to 0-10. I think I need to start reading the Arduino "getting started" and docs next...

The "1-10 V" spec seems a bit odd to me, but I guess it starts increasing brightness only after it gets more than 1 V. Or maybe there should be a base potential of 1 V there all the time... I could add potentiometers and use a voltage meter to adjust the output voltage to exactly 1-10 V.

It's going to be inside so the ambient temperature is between 20-25 C all year around.
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Is this your first time using arduino? If so, then yes, check out the get starting guide and try some of the basic arduino examples. Their are plenty there.
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Is this your first time using arduino? If so, then yes, check out the get starting guide and try some of the basic arduino examples. Their are plenty there.

Yes it is. I've been thinking about trying it out before, but now I have a project I could really use it for. Just wanted to have some comments on the feasibility before really digging into the docs.

Looks like it might work very nicely, in deed. It seems I could easily add an infrared receiver and use a very simple remote for the manual dimming function... that should be so foolproof I don't need any manual overrides for the dimming, just a main on/off switch in the controller box and everything else is controlled using the the IR remote (plus additonally ethernet/wifi connection from my computer).
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Looks like it might work very nicely, in deed. It seems I could easily add an infrared receiver and use a very simple remote for the manual dimming function... that should be so foolproof I don't need any manual overrides for the dimming, just a main on/off switch in the controller box and everything else is controlled using the the IR remote (plus additonally ethernet/wifi connection from my computer).

Yea, that is basically it.
How far away will this be from you or your computer?
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Yea, that is basically it.
How far away will this be from you or your computer?

10-15 meters max. The computer is in the next room but I've got CAT5 cabling done so I can use ethernet.
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I'll use the infrared whem I'm in the same room and computer from the other room smiley
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Ok, let me know when you start to build it.
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Ok so I need an op amp that I could hook up to the same power supply as the Arduino board, get the 0-5 out of the board and amp it up to 0-10.
In case you don't know this, you'll need a slightly more than 10V powering the op-amp.   Then, you just need an op-amp circuit with a gain of 2 (an op-amp and two resistors).

The Arduino doesn't have a true DAC.  It has PWM which can be filtered (with a resistor & capacitor) to get a variable DC voltage.
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Ok so I need an op amp that I could hook up to the same power supply as the Arduino board, get the 0-5 out of the board and amp it up to 0-10.
In case you don't know this, you'll need a slightly more than 10V powering the op-amp.   Then, you just need an op-amp circuit with a gain of 2 (an op-amp and two resistors).

The Arduino doesn't have a true DAC.  It has PWM which can be filtered (with a resistor & capacitor) to get a variable DC voltage.

Thanks for this! I was just doing some research about it. I bet the ballasts don't like PWM, so I I'm going to need a DAC. Looks like this guy already did all the hard(ware) work for me:

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

If I'm not mistaken, the Arduino seems to accept 12 V input power, which I'll feed to the DAC opamp as well. Well, actually I need both 12 V and 5 V... like an ATX power supply, but with a lot less power output. Maybe I could just drop down the voltage from 12 to 5 with a resistor because the currents are so small? I don't have much experience with low current electronics... don't worry, I know how to handle mains power.

I can even calibrate the output voltage to exactly 1-10 V with software. I'll measure the voltage with different output values and get a lower and possibly upper limit. It seems I can even read the output voltage directly from the Arduino... double check with a volt meter first. Looks great! Only worry now is that if the that DAC outputs only 9.9 volts or so, I will not be getting full output from the fluorescent tubes... maybe a potentiometer at R4 to adjust it?

All I need now is to add a couple of relays to turn the lights on and off.
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Well, actually I need both 12 V and 5 V... like an ATX power supply, but with a lot less power output. Maybe I could just drop down the voltage from 12 to 5 with a resistor because the currents are so small? I don't have much experience with low current electronics... don't worry, I know how to handle mains power.

Not really, you can feed the 12V into both the OP amp, and arduino, and then get a 5V regulator, to get the other 5 volts.

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Maybe I could just drop down the voltage from 12 to 5 with a resistor because the currents are so small?
DONT DO THAT, it will be a waste of energy, go with the regulator.
« Last Edit: December 06, 2012, 08:06:36 am by HazardsMind » Logged

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