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New inverter solves credit card processing problems!? — Parallax Forums

New inverter solves credit card processing problems!?

W9GFOW9GFO Posts: 4,010
edited 2010-04-01 16:20 in General Discussion
Okay, it was hard to think of an appropriate subject line for this.

My parents run a mobile tool business - like Snap-On. They have recently invested in mobile broadband and a card reader so that they can process credit cards without having to use their old standalone wireless unit.

In the literature that they were provided by the franchise they were told that they may need a new inverter (pure sine wave) to be able to use the system effectively. They currently have a modified sine wave inverter which the laptop and receipt printer is plugged into.

The only way this made any sense to me is if the new credit card reader used a power supply that could not tolerate the modified sine wave.

As it turns out, the credit card reader is USB powered.

Why on earth would a new inverter be required? My parents are the type that would have just spent the extra money, plus someone to install it, if I hadn't suggested that they just wait and see. So far everything is working fine.

Rich H

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Post Edited (W9GFO) : 3/29/2010 6:43:05 PM GMT

Comments

  • Erik FriesenErik Friesen Posts: 1,071
    edited 2010-03-29 17:58
    Sounds like a disconnect between the engineer and the manual writer.
  • W9GFOW9GFO Posts: 4,010
    edited 2010-03-29 18:30
    I attached linked to the flyer in the original post, it's not like the information was buried in a manual...

    Rich H

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    Post Edited (W9GFO) : 3/29/2010 6:43:56 PM GMT
  • IRobot2IRobot2 Posts: 164
    edited 2010-03-29 18:50
    My guess is they either wanted to sell you something you didn't need or you don't have the particular machine that requires it. I don't really understand why you would need it if it is currently running off of usb.

    I think Erik was trying to say is that some one misunderstood what the true requirements needed to be and they ran with it.

    Not to mention, if you *make* one customer buy a special gizmo and not the other one... some one is going to be very unhappy if they ever find out. Some times companies blindly lie to you because they are in to deep and won't admit that you probably didn't need it. If only every company was as trustworthy as Parallax...

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  • W9GFOW9GFO Posts: 4,010
    edited 2010-03-29 19:06
    IRobot2 said...
    I think Erik was trying to say is that some one misunderstood what the true requirements needed to be and they ran with it.

    I didn't mean to discount what he said - I agree. I just wanted to emphasize that the suggestion to upgrade the inverter was very prominent. It was sent in a full page email, it almost seems mandatory. Especially so when you consider that the target of the ad is non computer savvy people who need to avoid processing problems at all costs.

    Apparently, some peoples' problems were solved by the upgrade, that's the story anyway...

    Rich H

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  • IRobot2IRobot2 Posts: 164
    edited 2010-03-29 19:28
    Ah, I get you now. Sorry for the confusion.

    Well I did a little googleing because I am curious why they would go to all this trouble. Sorry if you said this already, but I think it may be that the end devices were overheating with only a modified sine wave inverter. This is because it squares off the wave without rounded corners. This would explain why it would work for you, but it is basically a dice roll or special circumstance that would start to blow fuses or overheat your equipment. Apparently this is happening to others so thats my guess. If you are powering it through a laptop you are probably getting some extra protection through that device (As long as your laptop can take it).

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  • W9GFOW9GFO Posts: 4,010
    edited 2010-03-29 20:00
    A quick Google searched showed only USB powered card readers. All of the mobile tool dealers already have laptops in their trucks. It would seem that if the laptops were okay with the modified sine wave inverters then the USB powered card reader would not change anything at all.

    Rich H

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  • icepuckicepuck Posts: 466
    edited 2010-03-30 23:23
    I've done business with four different snap-on dealers over the years and I asked a dealer one time why they used all the same hardware/software, it was because of snap-on's tech support not wanting to deal with different hardware setups.So one possibility is because of tech support.

    I recently replaced a cheap 400w inverter because the inverter would shutdown any time I would plug in the power supply for my Dell Mini. My new not so cheap 400w inverter runs the Mini just fine.
    -dan

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  • W9GFOW9GFO Posts: 4,010
    edited 2010-03-31 03:42
    Well, today he had problems with the card reader. His laptop has to be plugged in all the time because the batteries are shot. Maybe the modified sine wave is making it's way to the USB ports???

    I have rigged up a USB port that is powered separately from a 4 cell battery pack. We'll see if that makes any difference.

    Rich H

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  • Erik FriesenErik Friesen Posts: 1,071
    edited 2010-03-31 12:19
    I am highly skeptical that it is inverter related. Before he buys one, he needs to leave everything as is, run an extension cord from ac line power, and try it, in exactly the same location as where he has problems,if possible, or something to ensure that he is not throwing away money.
  • kwinnkwinn Posts: 8,697
    edited 2010-03-31 13:51
    To me this sounds more like the electrical noise from the inverter is interfering with the card reader or mobile connection. Try moving the inverter as far from the laptop and card reader as possible.
  • W9GFOW9GFO Posts: 4,010
    edited 2010-03-31 14:21
    kwinn said...
    To me this sounds more like the electrical noise from the inverter is interfering with the card reader or mobile connection. Try moving the inverter as far from the laptop and card reader as possible.
    They are 15 to 20 feet apart. The mobile connection (broadband) does not come into play until after the card has been swiped. The problem is that the card is not being read when swiped.

    Rich H

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  • W9GFOW9GFO Posts: 4,010
    edited 2010-03-31 19:15
    Erik Friesen said...
    I am highly skeptical that it is inverter related. Before he buys one, he needs to leave everything as is, run an extension cord from ac line power, and try it, in exactly the same location as where he has problems,if possible, or something to ensure that he is not throwing away money.
    I was too but it is looking more like a reality. My hacked USB port is not making any difference - it makes it so the card reader is powered by a regulated 5v off of a battery pack. It was tested at home but does not work on the road.

    We will try the extension cord thing this evening...

    Rich h

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  • kwinnkwinn Posts: 8,697
    edited 2010-03-31 21:19
    This is the kind of fascinating problem that I would often spend an inordinate amount of time and effort to figure out. Good thing it is not near by and someone I know. Apparently some interference or noise pickup from the inverter, but is it electrical, magnetic, or RF, and how is it being picked up.
  • W9GFOW9GFO Posts: 4,010
    edited 2010-04-01 01:17
    Here is what I have learned;

    The laptop and receipt printer are plugged into the wall outlet, which is supplied by the inverter.
    The receipt printer is connected to the laptop via USB and of course the card reader is connected by a USB cable.

    With the laptop plugged into the house via an extension cord and the receipt printer plugged into the inverter - the card reader doesn't work. Unplug the receipt printer (either the USB cable or the power), then it does work.
    With the laptop plugged into nothing and the receipt printer plugged into the inverter - the card reader doesn't work.

    Essentially, if there is any connection at all to the inverter then the card reader won't work.

    The solution for now is that whenever he needs to swipe a card he has to unplug both the laptop and the printer from the outlet, swipe the card, then plug them back in. I tried using a power strip so that he could just switch the power off and back on but that doesn't work - probably because there is still a path connecting the inverter to the card reader.

    I guess he really does need a new inverter. eyes.gif

    Rich H

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  • kwinnkwinn Posts: 8,697
    edited 2010-04-01 04:41
    You might want to try a DC-DC inverter to go directly from the car 12V system to the 18-21V input the laptop requires. I use one and have provided several others with them. So far they have worked without problems but I do not think anyone uses them for mobile POS equipment.

    Going from 12VDC to 120VAC then back to 18 to 21V DC just seems like such a roundabout way of powering a laptop.

    Post Edited (kwinn) : 4/1/2010 4:46:11 AM GMT
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2010-04-01 12:04
    Well, that is interesting. I suppose the rf noise is coming through the lines?
    Kwinn said...
    You might want to try a DC-DC inverter to go directly from the car 12V system to the 18-21V input the laptop requires. I use one and have provided several others with them. So far they have worked without problems but I do not think anyone uses them for mobile POS equipment.

    Do I understand that the printer is asking for 120V? How is that W9GFO?

    I don't know too much about internal workings on inverters, but would it work to clean up the edges with a combination of chokes and caps? Do you suppose that the sharp edges are what is causing the problems, or does it really have to be a sine wave?
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-04-01 14:29
    Going from 12VDC to 120VAC then back to 18 to 21V DC just seems like such a roundabout way of powering a laptop.


    I agree..

    Inverters back to a brick ..is bulky RF Noisy and Inefficient ..

    IMPO I would make my own DC-DC SMPS for each Device custom

    Or hack the Auto/Air DC-DC for the PSU ... most If you look carfully are easy to find the V divider so you can tweak the V Out a tad to any thing you want.

    As for your printer . its most likely taht the PSU is inside ..

    Making a DC-DC for it might need 3.3 5 and 12 and 24 V or so to run ..




    KG6LSE

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  • John R.John R. Posts: 1,376
    edited 2010-04-01 16:20
    Given that you're running a swtiching power supply with a switched power source, I could see a number of unobvious potential problems.

    * With a square(ish) wave, does the downstream equipment have a tough time seeing the zero crossing point?
    * Are we potentially looking at circutits designed to "flatten" a sine wave having issues "flattening" the square wave? (Does it require a a slightly different RCL circuit because of the longer time at full voltage, and shorter time in transition.)
    * Is there potentially more power to dissapate (and hence more heat) because of the wave form of the incomming power?
    * Are there unseen/unnoticed spikes at the corners of the square wave?

    Without putting a 'scope on a few points, there could be plenty of questions.

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