for controlling a 0-10v ballast fluorescent lamp driver (philips) I need a true analog output which can change from 0 to 10VDC.
after digging through the web I´ve found the following two possibilties and i kind of need your opinion on which one might serve best.
1: smoothing out the arduino pwm with a lowpassfilter and after that cranking it up from 5v to 10v with an opamp.
2: with a tip120 or so PWM controlling a 10V source and smoothing that out with a filter.
(3): besides that i was thinking of maybe voltage dividing a 10v suppply with an R2R ladder a uln2803 and a shiftregister.
(or with a digital potmeter capable of taking a 10v load (suggestions are welcome)?)
what do you think would work best.
I won´t have to change the voltage often (at most once every few weeks) and most importantly I need it to live long (years)
probably the system will power down every day.
the thing i kind of like about the voltage divide solution would be that i´ll only have to set the "output voltage" once and after that i won´t be using the timers for the pwm which leaves them free for other stuff.
what do you think, would that work? am i making it myself unnecessarily difficult (am i rebuilding a yet existing component?)
any other idea how i could voltage divide with the arduino?
How much current do you need to supply to the 0-10volt control system.
If very low (say 20ma or less)then a simple potentiometer will suffice (using say a 500ohm pot) with some slight non-linearity
If reasonably low (say less than 100ma) then a simple op-amp with a potentiometer input will do
If higher than 100ma then you need a regulator chip such as an LM317. These have a minimum output of around 1.5 volts but if you need to get down to zero then a couple of diodes wired in series will get rid of this
Using an arduino to provide a signal such as you require with very low change requirements is an absolute waste of technology.
jack
I haven´t been complete in the information I gave,
I wont use the arduino for just dimming a lamp, most importantly I need doing that wirelessly in some way.
being that with IR, or RF i don´t really know yet, maybe i´ll hook it up to an openwrt router. I haven´t really decided on this subject yet.
it´s a small domotica project.
about the current i dont really know, i haven´t found the datasheet on the ballast I use for now.
I know I cannot be more than 2A if i remember correctly and I believe it will allready work with very little current applied.
and what do you think about the not-using-pwm solution?
besides that i was thinking of maybe voltage dividing a 10v suppply with an R2R ladder a uln2803 and a shiftregister.
(or with a digital potmeter capable of taking a 10v load (suggestions are welcome)?)
while thinking about it yesterday i really kind of like the idea of not using pwm. if I also want to use IR and maybe an additional servo or stepper motor or so I might get in trouble with my timers.
PWM is the way to go, if the control current is small, then you will have no problem at all smoothing it with a relatively modest capacitor. I doubt that you will need to use an op amp.