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... where I was between 5 and 6.
Apparently "Kindergarten" was not an appropriate response.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Thanks - I needed that.
INTP
"Program testing can be used to show the presence of bugs, but never to show their absence." - Edsger Dijkstra
"I have never been lost, but I will admit to being confused for several weeks. " - Daniel Boone
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I am aware that it might be dangerous to power sensitive electronics from an inverter that outputs a modified sine wave as opposed to a pure sine wave.
Does anyone do this? Is it harmful in practice or only in theory?
I'm interested to ask because I only have a regular inverter, and I will need to power my laptop on the road soon.
The difficult we do right away...
...the impossible takes slightly longer.
modified 4-Jun-20 13:51pm.
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Are you ready for this discussion to go off on a tangent? 'Cos I think it will. 
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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That's just rhetorical hyperbole!
The difficult we do right away...
...the impossible takes slightly longer.
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Quick, someone fetch a cosh!
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Richard Andrew x64 wrote: Does anyone do this?
I've powered my laptops from a DC to AC converter that output a modified sine wave without any problems. Typically the inverters that you can get that plug into the lighter adapter of the car, but also I have a small solar battery charging system that I've used for a battery backup in the past, again, 12 VDC to 120 VAC and plug the laptop supply into that.
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Thanks for the report, Marc. I have also used the modified sine wave to power the laptop in the past and did not notice any problems. But I was just wondering.
The difficult we do right away...
...the impossible takes slightly longer.
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From what I researched when I was looking at UPS'es a few years ago, some PSU's don't like it at all: because the "modified sine wave" is actually a non-symmetric square wave (or worse a "chopped" square wave) I made sure I bought a true sine wave UPS. Which failed far too quickly: the sine wave was fine, the batteries were fine, but when it switched over the 5V / 3.5V / whatever for the processor failed and it turned itself off ... 
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Thank you, Mr. Griff.
I'm sorry to hear that.
The difficult we do right away...
...the impossible takes slightly longer.
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Chinese electronics ...
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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I've run into this as well. The real issue with modern power supplies (and any in the last decade or so) is the switchover time.
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A cheap inverter produce a square wave instead of a sine wave.
There are two problems with that.
A. A square wave produces harmonics really high up in frequency which, if badly filtered, can produce a high amount of interference with sensitive electronics. This can have very strange consequences.
2. In most switched power supplies, the input is first rectified and filtered through a capacitor to create a direct current
To produce the same power through a resistive load, the peak voltage of a sine wave is sqrt(2) higher than the peak voltage of a square wave. this means the voltage of the rectified direct current is 0.707 lower than the voltage from a square wave.
So for a switched power supply to create the same output voltage from a square wave as from a sine wave it uses 1.414 times higher current.
This is one reason brownouts break a lot of electric equipment.
So, I would take a good look at the power supply for how LOW voltage it accepts, if that is less than 0.707 of the nominal voltage of the inverter you don't need to worry to much I think, since switched power supplies are not very sensitive to higher harmonics.
Then there are some intermediate priced inverters producing something called modified sine wave, which is looking similar to a truncated triangle wave.
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Thank you, this was a very good post.
The power supply I'm using says it needs 100 to 240 volts. That would definitely fall out of the range you specified. If the inverter outputs 120 volts, then 120 * 0.707 = 84.84.
I think that's not too good, right?
The difficult we do right away...
...the impossible takes slightly longer.
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Not with an el cheapo inverter, but today there are switched inverters producing something like an acceptable waveform for not that much more money.
Or you can buy a 12V power supply for the laptop. Like for example this: Amazon.com: CAR Charger[^]
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I see. Thank you.
The difficult we do right away...
...the impossible takes slightly longer.
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Hi All,
I wanted to opions on slide to digital image conversion, I have the hardware and can convert them to jpgs, some of them are 'quite dark' to quote Mum, I was wondering if I captured them at a higher bit rate 96 instead of 24 and used a different save format I could them use some software (Paint.Net, Hypersnap or something else) to get more definition out of them? Just wondering... (also who thought Slides were a good idea?)
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Slides are awesome. Color negatives are Satan's own creation.
I can't really help you. I haven't scanned many of my slides. I mostly scan B+W negatives.
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Try the "Auto-Level" adjustment in Paint.net, it works quite well to fix the colour balance etc on old photos.
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I scanned ca. 6000 old color negatives with an Epson V500 photo scanner. And some slides. One of the things you can do is a reasonable color/contrast/etc. correction even prior to the scan.
In addition, you can use something like GIMP II (freeware equal to Photoshop) and really fix them up in any manner. What makes this a better route (if the images have any importance to you) is that you can operate on parts of the image, remove dust, scratches, and etc., as you so choose.
Where I work, for a while, I used to have an occasional call for employees to submit really old pictures of themselves which I would restore. The restored images were published in the company quarterly with a "Guess Who?" theme. Restoration can be a lot of fun. (More so, if you're paid for your time).
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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GIMP! I knew I was missing something... 
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Try GIMP[^], it's free and a good editor.
I'm not sure how many cookies it makes to be happy, but so far it's not 27.
JaxCoder.com
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Just as general advice, don't save them as JPG file - it's a "lossy" compression format, so you are throwing away detail to start with.
Save them as bitmap, or use a lossless compression format like GIF or PNG instead.
When you've adjusted them - and nearly every paint package can do that - then save the "release copies" as JPG to shrink the size, but keep the lossless originals in case of other work being needed.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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The only options with the el'Cheapo software was JPG & TIFF  ... BMP was my first thought.
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Can BMP handle 3*12 bits? I believe that TIFF has so many options that may be supported or unsupported, there is most likely a 12 bit option there. Question is if your software supports it.
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