Inverters--Pure Sine vs. Modified Sine Wave

Sluggo63

Sluggo63

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For her business, my wife wants to have access to a portable scanner in our car. Although it's a 2019, there aren't any 110V outlets anywhere. In the trunk there's a cigarette lighter outlet. I was going to run an inverter through that to power the scanner. I know there can be issues running electronics on a modified sine wave inverter vs. a pure sine wave inverter. My question is will it affect the scanner if the modified sine wave AC power runs though a DC transformer on the way to the equipment.

Car (12VDC) --> Modified Sine Wave Inverter (120 VAC) --> Transformer (24 VDC) --> Scanner

No problems with this set-up, right?
 
You might look into the amperage draw of the inverter to make sure it won't blow the fuse on the 12V receptacle.
 
Probably no way to guess the answer ahead of time. How expensive is the scanner? i.e. would anyone cry if it gets damaged by this experiment? I see a USB powered Epson ES-50 mobile scanner on sale at Best Buy for $99.99 today.

To the point above, I have an older Fujitsu ScanSnap S510M on my desk. It says 16V at 1.5A on the unit, and the power brick is rated to output up to 2.5A at 16V. Not sure what common fuse sizes 12V car outlets have. If the scanner transformer and inverter are each 80% efficient ( a guess), 1.5A at the scanner becomes about 2.35A at the 12V receptacle.
 
SoonerAviator said:
You might look into the amperage draw of the inverter to make sure it won't blow the fuse on the 12V receptacle.
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rpadula said:
Probably no way to guess the answer ahead of time. How expensive is the scanner? i.e. would anyone cry if it gets damaged by this experiment? I see a USB powered Epson ES-50 mobile scanner on sale at Best Buy for $99.99 today.

To the point above, I have an older Fujitsu ScanSnap S510M on my desk. It says 16V at 1.5A on the unit, and the power brick is rated to output up to 2.5A at 16V. Not sure what common fuse sizes 12V car outlets have. If the scanner transformer and inverter are each 80% efficient ( a guess), 1.5A at the scanner becomes about 2.35A at the 12V receptacle.
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Something like this inverter is what I'm looking at.

https://www.harborfreight.com/autom...-modified-sine-wave-power-inverter-56496.html

It's automotive, so I'm assuming it'll be able to run from the cigarette lighter.

This is what the DC transformer says. Looks like it’s pulling 120V at 1 amp.

4741CC40-E587-442B-A208-468A435FE775.jpeg
 
The more I think about this, the more I think I'm over-thinking this. DC is coming out of the transformer. DC is DC. I won't hurt the scanner. If anything gets damaged, it'd be the transformer, but since it accepts a wide range of Volts & Hertz, I'm pretty sure it can handle a modified dine wave.
 
What’s voltage can the scanner deal with? Might be able to run straight dc
 
Sluggo63 said:
The more I think about this, the more I think I'm over-thinking this. DC is coming out of the transformer. DC is DC. I won't hurt the scanner. If anything gets damaged, it'd be the transformer, but since it accepts a wide range of Volts & Hertz, I'm pretty sure it can handle a modified dine wave.
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If you were a geek you'd skip the inverter+power supply and just go get a 12v to 24v boost converter and an appropriate plug for the scanner.
 
chartbundle said:
If you were a geek you'd skip the inverter+power supply and just go get a 12v to 24v boost converter and an appropriate plug for the scanner.
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:yeahthat:

You don't even need to be a geek, universal computer power supplies that run on 12V are readily available. Much more efficient than an inverter.
 
As an EMC engineer of long standing, I would suggest that you go with a "real" sine wave, rather than a modified sine wave. There would be far less RF noise that would interfere with AM reception by the scanner. FM probably wouldn't care, but AM would.
 
OP, your set up should work just fine. Your "transformer" is actually a switching power supply that converts the 100-240V input to 24VDC. Small switching supplies will simply rectify the input to a high voltage DC, then convert it to the desired output voltage. Because the input gets rectified, it does not matter whether the input is a sine, square, modified sine, or even high voltage DC.
 
There are so many portable document scanners these days that I probably wouldn't even worry about vehicle power. I currently use an Epson DS-30 and DS-40. The current model equivalents are Epson ES-50 and ES-60W. the wireless feature was hit or miss for me on the 40 but YMMV.
 
Are we talking about a document scanner? Or a radio scanner? Or something else like bar code scanner?
Not that it makes much difference. I'm just curious.
 
Ghery said:
As an EMC engineer of long standing, I would suggest that you go with a "real" sine wave, rather than a modified sine wave. There would be far less RF noise that would interfere with AM reception by the scanner. FM probably wouldn't care, but AM would.
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JOhnH said:
Are we talking about a document scanner? Or a radio scanner? Or something else like bar code scanner?
Not that it makes much difference. I'm just curious.
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After reading @Ghery's post, I realized that it was ambiguous. I was talking about a document scanner, not a radio scanner.

I set it up like my first post: Auto->Inverter->Transformer->Scanner and it works.

Thanks all!
 
Sluggo63 said:
For her business, my wife wants to have access to a portable scanner in our car. Although it's a 2019, there aren't any 110V outlets anywhere. In the trunk there's a cigarette lighter outlet. I was going to run an inverter through that to power the scanner. I know there can be issues running electronics on a modified sine wave inverter vs. a pure sine wave inverter. My question is will it affect the scanner if the modified sine wave AC power runs though a DC transformer on the way to the equipment.

Car (12VDC) --> Modified Sine Wave Inverter (120 VAC) --> Transformer (24 VDC) --> Scanner

No problems with this set-up, right?
Click to expand...

First, referring to a transformer as a "DC transformer" confuses things. The conventional use of a transformer is in AC applications. What you are talking about is most likely a step-down transformer with a rectifier or a AC-DC converter. If big and heavy, it is likely to be the former; light and compact, the latter.

You are probably already using the "transformer" with the scanner - plug in the transformer into a wall socket which connects to the scanner. The scanner probably came with the transformer (called power supply).

What you described should work.
 
noahfong said:
First, referring to a transformer as a "DC transformer" confuses things. The conventional use of a transformer is in AC applications. What you are talking about is most likely a step-down transformer with a rectifier or a AC-DC converter. If big and heavy, it is likely to be the former; light and compact, the latter.

You are probably already using the "transformer" with the scanner - plug in the transformer into a wall socket which connects to the scanner. The scanner probably came with the transformer (called power supply).

What you described should work.
Click to expand...
Yes, thanks for the correction. I have the inverter plugged into the cigarette lighter jack in the car, turning 12VDC into 110 VAC. Then I plugged the power supply for the scanner into the inverter taking that 110 VAC and turning it back into 24VDC.
 
I'm late to the party, and don't have a lot of original comment to add, but I'll reinforce a few things.

  • Real Sine > Modified.
  • Whatever your choice, it's going to a transformer, then a full-wave rectifier before regulation. I doubt it'll make a difference in real life.
  • Inverters are traditionally inefficient, so check the current limits into the device.

Here's a sample of my thinking on the matter....

24 watts of power coming out, 50% efficient, means 48 watts going into the inverter.

48 watts at 12v is 4 amps. That's within the capacity of most cigarette-lighter plugs on cars, which, are usually protected with a ten-amp fuse.
 
chartbundle said:
Yea, that's gone to hell. I paid for it years ago now to use any feature I have to pay monthly.
Looks like there are plenty of other options now at least.
Click to expand...

Strange, I use it every week and don't pay anything. I have the full version which I paid once for long ago.
 
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