EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: gmi109 on October 15, 2015, 03:25:24 am
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Hello, I am trying to make an Arduino powered AC power supply. The idea here is that I can make a low current power supply that I use to output different frequency 50/60 Hz and voltage 120/240VAC to test switching AC/DC power supplies that I plan on making for future projects.
So far, I'm thinking that I can use an Arduino/DAC combination to generate a nice 0-5V sine wave at 50 or 60 Hz. This sine wave would need to be amplified to ~12Vrms and then put through a 12V/240V transformer. The part that is getting me stuck is how to amplify the sine wave. I'm a beginner and I'm not really sure of the best way to amplify this signal and have the appropriate amperage necessary for the transformer (I'm shooting for ~30 watts).
So my question is, what would you guys recommend for going from the 0-5V sine wave to either a +/-17 V sine wave or a +14/0 V sine wave (I believe both result in a 12Vrms sine wave?)? Right now I'm thinking it will have to be some combination of OP-amp and transistors/MOSFETs?
Thanks for any input you guys can provide.
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An Arduino? For that? :palm:
What you're looking for is an "inverter". Use that search term and you'll find more info...
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An Arduino? For that? :palm:
What you're looking for is an "inverter". Use that search term and you'll find more info...
Yes, I want an Arduino. Most of the inverter schematics that I've looked at so far don't have the ability to easily switch between 50/60 hz and don't have the ability to set current limits like one might want to for a "power supply". Not to mention a lot of the simple ones only do square waves.
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How much load current capability do you need at 120V and at 240V?
For low power loads, you may be able to use a step-up transformer driven by a class D audio amplifier module.
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He/she said 30W in the OP.
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There are dozens of audio power amp boards on Ebay that would boost your "line-level" sine wave up to something suitable for your step-up transformer.
As @Ian.M suggested, you could use a class-D amplifier for better efficiency, lower cost, lower heat, etc.
Not clear why you need a microcontroller to simply generate a switchable 50 or 60 Hz sine-wave?
Unless there are other features you didn't mention, this seems like overkill.
As a completely random example currently on Ebay...
New IRS2092 Class D 200W Mono Audio Power Amplifier AMP Assembled Board -- US$ 16.51
http://www.ebay.com/itm/New-IRS2092-Class-D-200W-Mono-Audio-Power-Amplifier-AMP-Assembled-Board-/141686135851?hash=item20fd26dc2b (http://www.ebay.com/itm/New-IRS2092-Class-D-200W-Mono-Audio-Power-Amplifier-AMP-Assembled-Board-/141686135851?hash=item20fd26dc2b)
(http://i.ebayimg.com/images/g/A0wAAOSwstxVRYYa/s-l500.jpg)
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How much load current capability do you need at 120V and at 240V?
For low power loads, you may be able to use a step-up transformer driven by a class D audio amplifier module.
Yes, I'm targeting about 30 watts. I've never dealt with class d audio amplifier circuits before, I'll look into that. Thanks for the suggestion
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There are dozens of audio power amp boards on Ebay that would boost your "line-level" sine wave up to something suitable for your step-up transformer.
As @Ian.M suggested, you could use a class-D amplifier for better efficiency, lower cost, lower heat, etc.
Not clear why you need a microcontroller to simply generate a switchable 50 or 60 Hz sine-wave?
Unless there are other features you didn't mention, this seems like overkill.
As a completely random example currently on Ebay...
New IRS2092 Class D 200W Mono Audio Power Amplifier AMP Assembled Board -- US$ 16.51
http://www.ebay.com/itm/New-IRS2092-Class-D-200W-Mono-Audio-Power-Amplifier-AMP-Assembled-Board-/141686135851?hash=item20fd26dc2b (http://www.ebay.com/itm/New-IRS2092-Class-D-200W-Mono-Audio-Power-Amplifier-AMP-Assembled-Board-/141686135851?hash=item20fd26dc2b)
(http://i.ebayimg.com/images/g/A0wAAOSwstxVRYYa/s-l500.jpg)
I realize that it is kind of overkill. I was wanting to have a nice LCD display where I could set the voltage/frequency and set a current limit so that it could cut the output if the selected current was exceeded. I'll definitely look into a class D amplifier, especially if there are cheap ones ready to go on ebay. Thanks for the suggestions!
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One of the reasons that you may want to use a MCU controlled solution is if you want to be able to simulate mains transients and various types of waveform dstortion.
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One of the reasons that you may want to use a MCU controlled solution is if you want to be able to simulate mains transients and various types of waveform distortion.
I hadn't thought of that, but that would certainly be something it could do too.
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I thought Class-D amps were created to give audiophiles something to gripe about.. :-DD so they are useful!
Pardon my doubt, but isn't the class-D audio output "tuned" for the impedance (damping, etc..) of a speaker? Wouldn't a transformer wired for step-up and just inches away, present a very different load? or require more output filter? Although they show 200-watts, it's likely only trustworthy for 50-watts in this application (and pardon the suspicion, somehow those nice Nichicon caps may end-up being CapXcon's by the time it arrives).
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I thought Class-D amps were created to give audiophiles something to gripe about.. :-DD so they are useful!
Pardon my doubt, but isn't the class-D audio output "tuned" for the impedance (damping, etc..) of a speaker? Wouldn't a transformer wired for step-up and just inches away, present a very different load? or require more output filter? Although they show 200-watts, it's likely only trustworthy for 50-watts in this application (and pardon the suspicion, somehow those nice Nichicon caps may end-up being CapXcon's by the time it arrives).
If you think the distance of a load (inches vs meters) is relevant in the audio band, then I'm afraid you might be the audiophool here!
Class D amps might come with output filters preinstalled for audio applications; although in the case of both transformers and speakers, the load is inductive and hence serves to smooth out the pulses coming from the Class D amp (which alternately shorts the output to Vcc and GND; once you add the inductive load, it's basically a buck converter). The OP wants 30W, the class D amp will output, say, 12V, that's 2.5A output, or an impedance of 12V / 2.5A = 4.8 ohms, which is pretty close to the mark for a typical speaker.
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I thought Class-D amps were created to give audiophiles something to gripe about.. :-DD so they are useful!
Pardon my doubt, but isn't the class-D audio output "tuned" for the impedance (damping, etc..) of a speaker? Wouldn't a transformer wired for step-up and just inches away, present a very different load? or require more output filter? Although they show 200-watts, it's likely only trustworthy for 50-watts in this application (and pardon the suspicion, somehow those nice Nichicon caps may end-up being CapXcon's by the time it arrives).
If you think the distance of a load (inches vs meters) is relevant in the audio band, then I'm afraid you might be the audiophool here!
Class D amps might come with output filters preinstalled for audio applications; although in the case of both transformers and speakers, the load is inductive and hence serves to smooth out the pulses coming from the Class D amp (which alternately shorts the output to Vcc and GND; once you add the inductive load, it's basically a buck converter). The OP wants 30W, the class D amp will output, say, 12V, that's 2.5A output, or an impedance of 12V / 2.5A = 4.8 ohms, which is pretty close to the mark for a typical speaker.
That was in jest. I find alternate use of cheap ebay modules interesting and honestly thought there would be a disparity with the loads.
Yes, I have humorous debate with an audio-fool family member about his Threshold "Stasis 500" amplifier and monster cables etc..
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...don't have the ability to easily switch between 50/60 hz
whats the point?50 and 60 dont have much difference...
and don't have the ability to set current limits like one might want to for a "power supply".
to current limit a 120/240V mains system means at one point your psu is going to lower that 120/240V which is not going to happen in real life... so to simulate that system on a offline smps is pointless imho... current limit in most offline/ac smps i've seen at least is happening in the step down (smps) transformer, thats where you need to look at imho, ymmv..
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...don't have the ability to easily switch between 50/60 hz
whats the point?50 and 60 dont have much difference...
and don't have the ability to set current limits like one might want to for a "power supply".
to current limit a 120/240V mains system means at one point your psu is going to lower that 120/240V which is not going to happen in real life... so to simulate that system on a offline smps is pointless imho... current limit in most offline/ac smps i've seen at least is happening in the step down (smps) transformer, thats where you need to look at imho, ymmv..
I understand that. It's more of a safety feature to prevent me from blowing up my AC/DC switching converters that I plan on testing with this. The same reason that you have CC modes on DC power supplies....