Square-waved question

[Per Walthinsen]

Since I'm in the process of being dragged into using a laptop (sort of against my will. I thought old guys on the far side of 65 were mercifully exempt from this) I might as well accept it and make use of it. The wife is eyeing some games, oh yikes.

Laptop, film scanner, external hard drive (and maybe a muffler-bearing analyzer): are there any possible harmful effects to these devices from running them with a small inverter of the garden-variety type, specifically since they produce square waveforms and not sine waves? I know, this is not camping, but when the winds howl and the rains pour it gives me another option and may keep my Photoshop skills from getting rusty (or maybe lets me do what I have to do in very pleasant surroundings).

Anyone have devices go south with these inverters?

[peterh]

Since I'm in the process of being dragged into using a laptop (sort of against my will. I thought old guys on the far side of 65 were mercifully exempt from this) I might as well accept it and make use of it. The wife is eyeing some games, oh yikes.

Laptop, film scanner, external hard drive (and maybe a muffler-bearing analyzer): are there any possible harmful effects to these devices from running them with a small inverter of the garden-variety type, specifically since they produce square waveforms and not sine waves? I know, this is not camping, but when the winds howl and the rains pour it gives me another option and may keep my Photoshop skills from getting rusty (or maybe lets me do what I have to do in very pleasant surroundings).

Anyone have devices go south with these inverters?

Genarally speaking laptops have fairly robust power supplies that can handle a wide range of input voltages and "dirty" (like cheap inverter) power, but this is not true of many peripherals like scanners and external hard drives.

[Per Walthinsen]

Thanks, Peter,
I checked both units I'll be using and the little Minolta 5400 scanner runs on 24v from a brick, the IOmega HD runs on 12v, also from a brick, both bricks are wall-type and the original ones supplied. Is it possible that since they are external bricks they will filter the corrupted AC sufficiently to be harmless? No problem with the laptop (hasn't arrived yet) but I can always use it on the battery if necessary. Yes, I know this is inefficient, but the trailer batteries are good sized, so it may work. Should I try it?

[Darwin Maring]

Laptops run on DC voltage. The first thing they do when you plug them in is to take the AC and change it to DC and they usually work on a wide range of AC 110 – 220 VAC at 50 to 60 hrz thus the square wave would be cleaned up to a good DC voltage.

The AC to DC power supply is usually outside the PC with the DC side plugged into the PC and the AC side plugged into the power so being that they run on DC inside the Laptop, you may be better off purchasing a DC to DC device and run the thing directly off your 12V DC receptacle in the vehicle.

When U use the inverter, U use more power than just using DC to begin with. You take DC, convert it to AC then convert it back to DC again. Just cut out the middle man and run directly off the 12VDC.

If U want to do WIFI, U will need a WIFI card that will plug into your laptop.

This way, while U R driving and refusing to stop to ask 4 directions, U can have your wife search the web for a length of flight line, a gallon of prop wash and a metric Crescent wrench 4 U.

U can also get GPS SFW for the laptop so she can yell in your ear when U make a wrong turn.

[Bonnie]

I have run my laptop on long road trips using a generic 100 watt inverter. It worked fine. I did have the brick between the computer and the power, so I didn't see any difference. We were using it to watch movies. It wasn't the best method; but it did work. I know Gina uses her lap top quite a bit and has some recommendations in her solar primer. It's linked in the document section.

I'm planning on using my laptop with or without power, so I have an interest in how others are managing this; short of shore power.

Bonnie

[Brian B-P]

There is quite a range of designs and quality levels in those "bricks", "cubes", "wall warts", and whatever else the AC-to-DC power supplies are called. The ones which handle 100 to 240 volts, 50 or 60 Hertz, etc. probably produce nice power with whatever inverter is used. Some of the others may not be so tolerant, but I can't give a concrete example of one which would have a problem.

The problem with just using the 12VDC directly is that many DC devices don't run on 12V - none of my laptops ever have. To avoid an inverter, a DC-to-DC supply usually intended for automotive and aircraft use is the solution. They're expensive enough and batteries last long enough that I haven't seen anyone use one for a while, but there are some slick looking designs available. The travel accessory stores at airports have lots, and mass market electronics places like Best Buy usually have some.

The Targus Mobile 70 Universal AC/DC Adapter is a newer version of an adapter I have, but mine works only with AC input, and this one takes AC or 12VDC, putting out whatever DC power you need. This would likely be more efficient than the double conversion (of inverter then AC-to-DC), would not suffer from square-wave power issues, and is a tidier travel solution. There are similar products of various brands.

[Brian B-P]

More directly answering the laptop-via-inverter question: we have used a couple of different laptops in the Boler. When the battery has needed charging, we have just used the normal AC-to-DC brick that came with it, sometimes from shore power, but also from a common inverter in the van, off the van battery; nothing got hurt. I never have wired up a 12V supply in the Boler to run anything not built-in.

[Larry&Carrie]

Ok so maybe I'm being a smart butt here, but when I'm in my scamp I'd rather have a good book. We have also found some real fun places because I REALLY don't know how to read a map. Never would have found these places with a gps..... Just me though.
Carrie

[Gina D.]

I have used different kinds of invertors to walwart to comp combinations. Cheapies and expensive sine wave ones. I have no issues with either.

The trick, for me, is to utilize the laptop battery as much as possible, then recharge it with the comp off, then go use the laptop again, battery only. This draws less then if you try to use the comp inverted, you don't have to have the power to light up screens, run processors etc. (Your laptop battery will do this later)

I have a small 9ah battery that can be charged directly (DC to DC) off my cars accessory port (Cigarette lighter for the old skool folks ) and I then charge the comp off of that, rather than the house battery.

Since the comp is not anywhere near a necessity, if I have no way of charging it, I am not going to die of withdrawal..

I have not had to go without with this system, however.

As far as WHY I take it with me... at night, I am not much of a reader, video or TV watcher, and the net provides my evenings entertainment. With a broadband access Rev A "Air Card", I have the net available almost anywhere, anytime. Finding Hot Spots is not a concern for me.

There are also often times (Quite frequently, actually) where on weekends, my choice is to work in my office, at home, or at least get something out of my saturday and work in the trailer while out having somewhat of a life. Spending saturday in my office, where I have been all week.. does not appeal, especially since my wallet gets no thicker from doing so.

[Gina D.]

(sort of against my will. I thought old guys on the far side of 65 were mercifully exempt from this)

Oh, Per... you will like it.

I no longer own any desktops, as a matter of fact, I set the 3 I had up on the street last weekend (Sans Hard Drives) and cleared MUCH space in my house. Mastering a touch pad is SOOOO liberating.. no clutter, no junk.. and it goes everywhere.

Fred is not real happy about it tho...

[Byron Kinnaman]

Without getting all technical on you, it won't be a problem. The transformer in the "brick" power supply for your laptop will make it sin wave is short order. Voltage and frequency are more important than wave shape of the AC power.

[Per Walthinsen]

Thanks y'all for the encouraging replies, and thanks, Byron. Gina, time will tell whether I can break away from the mousey thing, maybe a Bluetooth mouse is going to happen. I think I will approach it much like you do, enjoying doing what I have to do in pleasant surroundings right outside or inside the Burro.

Our older desktop set crawls with Photoshop and large scanned files, and this one will be much faster, but what set this off was that I've struggled with scanning software from a well-known German company for more than five years. Periodically I got fed up with its utter lack of reliability and predictability, despite expert tech support at home and indifferent support from the manufacturer. Son: "They are really lousy at writing code."

Suddenly something stirred deep in my consciousness: wasn't there some other kind of highly-touted software available for this. Hmmmm... Then I found it, downloaded it and voila! my scanners hummed, my tasks got done, and I stared progress straight in the eyes.

Software from a small company in Phoenix, but it works like a charm, is extremely capable and configurable and has a really good interface. I'm a happy scanner.

The only thing is, I must apparently learn to cope with the latest and the greatest thing from the laptop manufacturers: shiny, mirror-like screens. Whose "brilliant" idea was this anyway? Waxpaper, anyone? Steel wool?

[MyronL]

Per...why the heck do you need a scanner, anyway?? Don't tell me you are shooting and scanning slides or negative film, are you? Yah, you may be old but you can't be THAT old!

My laptop is an old NEC Pentium 3 with pathetic RAM but I got it (used on Ebay) specifically to process pictures on the road. It works fine. No scanner needed.

I shoot with an equally old Nikon D100 (with all my old --hell, ancient Nikon lenses) that takes a Compact Flash card. So I bought a SanDisk Compact Flash PC Card Adapter $14--? that plugs into the laptop LAN port (still with me, old timer?) and ANY picture software will read and transfer picture files onto the hard drive of the lapT. Or, just use Windows Explorer.

A variety of card readers for any camera are available. Got mine at Staples. Scanners?

Oh, wait, I get it. When you're out there deep the Oregon woods and you finish a roll of Velvia or Kodacolor 100 you just run over to the nearest drug store for processing, wait half an hour, then take your film back to the Burro so you can scan it. Ahhh-ha-ha-ha-hoo-hah!

[Donna D.]

A variety of card readers for any camera are available. Got mine at Staples. Scanners? Ahhh-ha-ha-ha-hoo-hah!

Often the assumption is made that people are using scanners to scan recently taken pictures...and maybe they are...or family snap shots from the 1950s perhaps for archiving or sharing across the web. But I have two scanners and use they both frequently...because I scan documents. If I can get the originial documents in their source files..then too I wouldn't need my scanner but most often everything I get is in printed form...sigh.

[Byron Kinnaman]

Thanks y'all for the encouraging replies, and thanks, Byron. Gina, time will tell whether I can break away from the mousey thing, maybe a Bluetooth mouse is going to happen. I think I will approach it much like you do, enjoying doing what I have to do in pleasant surroundings right outside or inside the Burro.


The only thing is, I must apparently learn to cope with the latest and the greatest thing from the laptop manufacturers: shiny, mirror-like screens. Whose "brilliant" idea was this anyway? Waxpaper, anyone? Steel wool?

I use an inexpensive Logitec wireless mouse with my laptop. It's smaller than a standard desktop mouse but larger than the itty bitty things.

You can get anti-glare filters, but aint cheap.

Sometimes I've had to move a bit avoid the glare. Wearing a dark colored shirt helps too.

Enjoy your new toy.

[Byron Kinnaman]

Per...[b]why the heck do you need a scanner, anyway?? Don't tell me you are shooting and scanning slides or negative film, are you? Yah, you may be old but you can't be THAT old!

Oh, wait, I get it. When you're out there deep the Oregon woods and you finish a roll of Velvia or Kodacolor 100 you just run over to the nearest drug store for processing, wait half an hour, then take your film back to the Burro so you can scan it. Ahhh-ha-ha-ha-hoo-hah!

You don't have to be very old to have a closet full of 35mm slides and a desk drawer full of prints. Some of us switched to digital soon as possible, but now what do we do with all those slides. Mine number close to 5,000.

When people make comments indicating the Oregon might be a bit behind the East Coast I have to remind them where Intel (Oregon) and Microsoft (Washington State) are. And there are places with names like Silicon Valley (California) and Silicon Forest (Oregon).

If you've ever been in Oregon you'd know that there are places where it's a long ways to the nearest drug store, and they wouldn't have 1 hour photo processor either.

[Herb P]

The issue with square wave vs sine wave vs modified sine wave inverters really comes up when using certain switching power supplies as well as inductive devices...

There are a couple of ways to convert high voltage AC to low voltage DC. One is to use a 'linear supply' which is basically a rectifier (2 diodes to convert the positive/negative swinging sine wave to a lumpy but all positive level), a transformer to squish the level down to where you want it, and capacitors to smooth things out. This sort of supply is relatively indifferent to a square wave.

The other way is to use a switching supply which is more complicated but more efficient and uses a lot less copper and easier to make tolerable of AC levels and frequencies (110-240 50-60hz for example). Modern laptop supplies use switchers. If your "wall wart" doesn't feel heavy, there's probably a switcher in it. Some poor quality switchers are highly intolerant of square wave AC. They will work but you'll hear an annoying and high pitched whine, the supply will get really hot, and could simply overheat and die. I'd be surprised if any current (last 2 to 3 years) laptops have switchers that are intolerant to cheap inverters... I think manufacturers understand that there are cheap inverters out there and that people are likely to use them.

The other problem with cheap square wave inverters is with an inductive load. Basically, anything with an AC motor (a drill, skil saw, blender, food processor, personal massager). The way these motors are wound, they pretty much require a nice true sine wave. With a square wave, they may turn slowly or lock up and hum loudly... They will get hot and in short order, you will probably smell magic smoke as the windings burn off their lacquer.

Probably more technical than people want, but I figured it was important to understand when you might want to invest more in an inverter.. A good dietary source of relatively decent quality inverters that people may not consider but has done me in good stead in the past, is old computer UPSes. People tend to throw these away when the batteries die but often, they can be coaxed to take 12V via another means. I have a 1kva inverter that takes 4 12v gel cells and which produces an absolutely beautiful sine wave. Sadly, it weighs 60lbs without batteries.

[Per Walthinsen]

Thanks, Herb.
They are the light-weight variety, but only the one for the HD is a 110-240 version. I mentioned this to my son, thinking he'd know nothing about it. Big mistake, wouldn't you know it. He agreed they both are switchers, but started talking about a water-bucket analogy, EU compliance markers, and PFC circuits. No EU marks on them, not a good thing.
I might search Waeco for possible replacements if needed, should be possible. Sine-wave inverters are spendy.

Myron: don't get me started. Byron and Donna have it: a lifetime of slides and negatives stashed away, and family pictures and negatives going back as far a 130 years. Before the software became completely impossible I rescued and digitized quite a few, fixing scratched, soiled and otherwise damaged items with Photoshop. Now it appears I'm back on track.
I, like Byron, may be a little sensitive about our deep woods environment here, but we try. Yes, I use a 8 pigamexel Canon DSLR and some Image Stabilizer lenses to keep my shaking hands from transferring to the images, but I hedge my bet with a Canon FTb system I've kept as insurance.
After scanning I send my files downstairs to a RAID system which unfortunately only has about 650 Gigabytes left in memory. Time for an upgrade. New Jersey!?

[Byron Kinnaman]

Herb,

Maybe you could explain what would cause a switching power supply to get hot when powered with a square wave, or dirty power source. After looking a couple schematics and thinking about it I can't think any reason for a large loss of efficiency.

I think the biggest objection to square wave or modified wave inverter output would be interference caused to radios and maybe some audio and video devices. Big old inductors, like motors will intergrate the square wave. Maybe a capacitive start motor could have trouble starting?

A switcher works the same way as a linear supply only the transformer and filtering elements can be much smaller because of the "switching". The linear part operates at a much higher frequency than a standard linear. The input still goes through an inductor which intergrates the square wave to some extent. Then into a bridge with filtering before the swiching circuit.

[MyronL]

Per, you're kidding, right? When my hands shake I upgrade to a tripod. When my dedicated slide scanner died I switched to an Epson 2450 flatbed to scan the 6 zillion-plus slides I have shot. Never thought to take that work with me to the woods, though. Maybe now, I will. (...Nah.)

Actually, Byron, I am familiar with Oregon. After breaking my heart my first love ran off to Klamath Falls with the other guy. Oh, and I saw Oregon on the horizon from 60 thousand feet, coming back over the Pacific, once.

Put down yer guns, fellas. Ain't no call for no defensive posturing. Be glad for the deep woods. To me, you are the envy of the world. Can’t go a hundred yards in some eastern parts of the "...cough...Garden State" without running into a gas station, drug store, paved parking lot, ek-setter-ah. Anybody shows you pictures of Jersey farmland... remain skeptical. Unlike in the great northwest, probably done with Photoshop.

You're AC with me, Herb. You're right, Donna. Never make assumptions because when you do, you.....