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Forum Index : Electronics : Another Inverter Build
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KeepIS Guru  Joined: 13/10/2014 Location: AustraliaPosts: 1840 |
In the "Nano Hex and Menu.PDF" Select "Various NANO board Modifications" from the Index. It's the 2nd image titled "Board 2 with a CH340 USB controller" Nothing in the Inverter SPWM code or timing has changed, and of course it's silent in both the Test inverter and the Beast. But as you mentioned, there are so, so, so, so many variables in these DIY builds, I could list a dozen right off, any one of which could influence the Toroid AC generation noise levels. I went through that phase after a high current incident, there was a buzz in the Toroid at idle all the time. I used the Same Toroid in another build, and it was silent  It was not your settings, I have the margin set quite high when checking the running status.  Edited 2025-04-30 08:46 by KeepIS NANO Inverter: Full download - Only Hex Ver 8.1Ks |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2434 |
Re the reset capacitor, probing a Nano the reset pin is connected to the small one bottom right in your pic. Close to the header pins and also connected to the 1kΩ (102). The other end of the cap. goes to pin 12 of the CH340G. |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1124 |
Yeah, I see it on the picture of board 2 the little cap is in the same place but the track looked to go under the CH340 on the one I have, and the 662K 3.3v sot23 voltage regulator (top left) made me look at the last nano in the list.  So if its the same its easy to knock off that little cap. Ok thanks Phil, I should get the probes and check. Edited 2025-04-30 09:30 by Revlac Cheers Aaron Off The Grid |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1124 |
Finally got around to making an enclosure for the current meter, Designed and 3D printed for the PZEM-051 and others etc, fits ok with some little file work and trimming. The only other change in the meter reads 16w now, it was reading 12 watts, whats up with that....nothing. Intend to make one out of better material, this is PLA just for a test fit.  Cheers Aaron Off The Grid |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1840 |
Still a very nice job on that housing. Have you tested the accuracy of the DC current readings in those meters? I'm finding that some similar units are out a bit, and I like the simpler display on yours. Edited 2025-05-06 07:17 by KeepIS NANO Inverter: Full download - Only Hex Ver 8.1Ks |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1124 |
I have quite a few of these meters and most of them have a cut or two in the shunt when they were initially calibrated, I doubt it was done to perfection. This one seems to be quite good at higher power levels, but I will have to check the lower idle power it measures on the inverter, next time its shut down I can check on this with the current limited power supply.  The printed case works well and I made it with some room inside so the wires fit in easily, had second thoughts on the design of the lugs holding the case to the cabinet. Cheers Aaron Off The Grid |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1124 |
Inverter has been running well, voltage is set to 230vac and it holds it very well, just a small deviation of +/- 1volt, Though I found a significant voltage drop under load the other day. I was using the heatgun on High, through a speed controller, "AC 220V 10000W SCR Speed Control" and the inverter output voltage dropped down to 217vac on one occasion that I noticed, Decided to have a look at the signewave with the little scope to see if it was bad or something to worry about, as it turns out, it was mostly the peak of the wave that was getting chopped with the SCR switching, when running at higher power the voltage wile rise back up again. I don't think it is a problem on its own but weather it will be while running the house, don't know yet, haven't noticed any noise from the inverter as the heatgun is so noisy anyway and I can't be in 2 places at once (tried it) will try something later, the inverter seems to survive it just fine.  I have been using this heatgun with speed controller for years on the HF inverters and haven't seen as much voltage drop. Now when I switch the heatgun to low and use the speed controller, I think everyone knows and has seen the single diode effect on the signewave, and is the reason I don't use low speed anymore.  Cheers Aaron Off The Grid |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1840 |
Hi Aaron, hopefully those little meters are true RMS meters and also allow for highly reactive and highly distorted AC waveforms when calculating output. Inverter feedback loops are not usually true RMS detectors so there can be more voltage variation with highly distorted loads. The Inverter will make some noise when a load starts pulling current from only ONE half of the AC cycle. However it does not seem to bother the Inverter in any way, you will find that with more inverter loading, especially resistive, that the heat gun noise will be lower, our Hot water system at nearly 3kW will swamp the effect of the Hair dryer that my wife occasionally uses. Apart from the visible spike in the AC waveform, there will be all kinds of ripples and wobbles from high Harmonic distortion created by these bad load. I don't really see much change in voltage with the Dual Toroids now, but that's just one of the many nice effects of having a really Big stack of Toroids handling these loads, actually the Hairdryer (diode in AC on low) is the only load that is slightly audible. BTW: I had a really good look at Input currents under these loads, and there is really nothing much at all to see, it appears a case of its bark is worse than its bite, even with a Diode on low setting in the Hair dryer.  . Edited 2025-05-14 08:46 by KeepIS NANO Inverter: Full download - Only Hex Ver 8.1Ks |
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wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1203 |
Dex had a similar fault when inverter noise was upsetting the voltage control, under higher loads the output voltage reduced. Try putting a 10n ceramic capacitor as per the picture (white circle either 0.2 or 0.3 pitch) and then re-test to see if it is improved. (This "cure"? assumes a metal standoff to the chassis below for the screw on that corner)  Edited 2025-05-14 12:57 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1124 |
I wasn't sure if the meters were giving me the full picture, the one on the wall at the switchboard was the first one I noticed the voltage drop, to further check what was going on I used another meter and located that near where I was using the heatgun and could get the picture and short video of the the voltage drop, this was also at the end of a 20 meter lead which shouldn't make much difference. Using the little DSO there was a drop in the signwave amplitude could also see it in the video clip, even more with the heatgun on low, played it a few times to be sure. Later today I used the phone sound recorder to see if the transformer makes any different sound, (mounted about less than half a meter from the transformer) could barley pick up any sound at idle, then with the heatgun running at half speed/power 10 meters away, there was just a small buzz sound recorded but not very loud, interestingly Tried it again and walked back to the inverter and there was no voltage drop on the inverter Display, still reading 230v....that was interesting and a few things to consider. I posted a photo of the output filter that I hadn't finished connecting properly, there is a fuse left in place from the original inverter, the output relay is after that, the the VFB gets its feed before the fuse, I should probably annihilate that fuse.  I had been thinking about that, I forgot to post a picture of what I had done  Made up an aluminium shield under the controller PCB and wired that to the ground pin on the PCB, not sure if it was best way to do it but the voltage has been very stable with all other loads I have thrown at it. It might still be stable at the VFB, I will have to check the voltage at either end of the filter and that fuse. Cheers Aaron Off The Grid |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1203 |
The fact that the meter on the inverter shows the correct (incorrect?) voltage although other meters downstream show a reduced voltage (the real voltage) I think is more proof that inverter noise is corrupting the regulating feedback signal to the Meter and Nano. The corrupted feedback signal may have noise riding on top of the feedback sinewave and once the feedback + noise equals the Nanos target voltage it happily regulates to what it sees and the meter also displays what it sees, hence the error. Killing the noise lets them both see the true feedback voltage. The AC feedback is best close to the external output ie after filters etc (but before any fuses or relays) as that would cause the output to go to maximum if the relay or fuse opened as there is no feedback then. Edited 2025-05-14 21:17 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1124 |
Ok thanks, thats how I have it setup, I might try something else later, it doesn't seem to be a problem and will check it again after adding another toroid etc. I mostly use the heatgun up the shed, haven't checked for voltage drop etc on that inverter. Cheers Aaron Off The Grid |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1840 |
That can induce more noise, remove lead and place with a cap (as per wiseguy) on the PCB, the internal PCB ground plane is connected to the PCB mounting hole, which is the connection point to the aluminum plate that the PCB is mounted on. Actually you can easily drop a few volts across 20m of extension with a 1kW heat gun. NANO Inverter: Full download - Only Hex Ver 8.1Ks |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1203 |
KeepIS, I did not see the yellow wire that Revlac was grounding the PCB plane to the chassis, thanks for commenting. However I also want to clarify that the PCB ground plane is not physically connected to the screw on that corner of the board. If you insert a capacitor into the provided pads/holes then the ground plane is connected RF/noise wise to the screw and thus the chassis. If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1840 |
NANO Inverter: Full download - Only Hex Ver 8.1Ks |
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