i'm facing a big problem: need to make an Arduino controlled AC sine generator. The unit have to be powered from the grid - 220VAC (12 VDC powered version is on the horizon) and have to have ability to generate regulated AC from 0 to ca. 60 VAC @ 50/60Hz. 50 or 100 Watts would be great.
Do you guys know or have idea how to make it?
I thought about it like this:
220VAC to DC power supply of appropriate wattage -> Arduino SPWM generator -> MOSFETS -> output transformer. But how to control output voltage?
220VAC to DC power supply -> audio sine generator as input for -> audio amplifier -> output transformer instead of speakers. Arduino should control amplifier gain so output sine wave RMS voltage can be controlled.
bogus105:
2. 220VAC to DC power supply -> audio sine generator as input for -> audio amplifier -> output transformer instead of speakers. Arduino should control amplifier gain so output sine wave RMS voltage can be controlled.
If you use a class-D power amplifier that runs on a +45volt and -45volt supply, and use it in bridge mode,
then you don't need a transformer.
Some even come with an onboard mains power supply.
Then all you need is a ~0-1volt amplitude controlled sine wave.
Leo..
i'm facing a big problem: need to make an Arduino controlled AC sine generator. The unit have to be powered from the grid - 220VAC (12 VDC powered version is on the horizon) and have to have ability to generate regulated AC from 0 to ca. 60 VAC @ 50/60Hz. 50 or 100 Watts would be great.
Do you guys know or have idea how to make it?
I thought about it like this:
220VAC to DC power supply of appropriate wattage -> Arduino SPWM generator -> MOSFETS -> output transformer. But how to control output voltage?
220VAC to DC power supply -> audio sine generator as input for -> audio amplifier -> output transformer instead of speakers. Arduino should control amplifier gain so output sine wave RMS voltage can be controlled.
I agree with the variac idea but I would like to suggest that the audio amplifier is also going to be relatively easy.
Use a Teensy with a direct 0-3.3V analog output pin to simplify it further. A Due would also be easy but its analog output is 1.65V to 2.6V or something odd like that, so it requires more calculation.
sterretje:
I have no idea how to design something that can create a powerful 60V AC from 12V DC.
There might be car booster/amplifiers that run on 245volt, don't know.
The ones I have repaired worked on a 230volt or so supply (made from the 12volt supply).
That only gives you a maximum of ~40volt AC in bridge mode.
A smaller class-D bridgemode car booster amp with a 1:2 transformer could do,
but I don't see where you are going to find a ~100watt 30volt to 60volt transformer.
A (motorised) variac might not be isolated from the mains (autotransformer).
ted:
google; 12v to 120v inverter circuit
OP wanted 60volt max, and inverters don't make good sinewaves, and you can't regulate them to 0volt.
Leo..
but I don't see where you are going to find a ~100watt 30volt to 60volt transformer.
A 100V line driver transformer, as used in PA systems in eg railway stations and big stadiums might be something like what you need....
I don't know where you live, bogus105, but here in England there are bespoke transformer makers who will knock up a special for you.
Sowter in Ipswich are excellent. I've used them for several curious jobs. I knew the founder many years ago. Or St Ives windings, now Carnhill. Ditto. There are a crowd in Earith, whose name I forget. Belclere in Oxford. Marinair ..... Chelmsford? I'm sure there are many more in East Anglia.
But not cheap.
Look in your local trade directory. Ring one up and discuss your problem.
The whole thing behind is i need to drive a 'smart tint' / 'smart film'. These are sticked to the window and are milky when not powered. If you apply sine @ ca 60VAC (need to confirm frequency yet) it become almost fully transparent.
I plan to make multi channel driver to be able to control, say, eight windows each one with its own transparency level.
I plan to make multi channel driver to be able to control, say, eight windows each one with its own transparency level.
I'm trying to understand if this is a hobby project, commercial project or a single installation trying to go the low cost route. I would have different answers to each.
For commercial I would design a class-D amplifier with a high frequency output transformer and filter that can provide the voltage(s) you need.
For a hobby I would purchase a single class-D amplifier (perhaps on ebay) then drive a 120V/12V transformer backward.
Note: 60V => 60 * 1.414 = 85 volts peak.
You could generate a generate an 12v sinewave power the transformer and get
12V X 120 / 24 = 60v.
Remember this is RMS, you will have to pick input power to generate the 18 - 20 volt peak you will need
To make the whole system safe and reliable is not a trivial task.
In the US, "low voltage, aka Class 2" wiring can be used. This is doorbell, thermostat, low voltage LED usage and can use a simple wiring method.
At 60Vac I believe you are no longer Class 2 so your wiring requirements will be more stringent.