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We have a device that uses an 18v adapter/power brick, unfortunately the adapter broke. As a replacement, we are considering an adapter that has a "18v ~ 20v" rating printed on its back. There is no switch whatsoever on the power brick to adjust the output voltage. The person selling the item says that the voltage will basically adjust itself based on the device being powered.

Question: Can I use a power brick labeled "18v ~ 20v" for a device that originally had an 18v adapter? Or will this be harmful to my device? Could the self adjusting voltage statement be true?

I understand that for voltages, it is necessary to look for an exact match, while for the amps, we just need to match the minimum. It's just that it's the first time I saw a "~" in the voltage indicator of a power brick. I'm really hoping to be able to use this, since other available options are 19v.

EDIT:

About the device being powered: This is the machine meant to be powered by the adapter: https://cricut.com/en_us/machines/cricut-explore-air-2.html

A video of it in action: https://www.youtube.com/watch?v=LdkyoMDQ5Pw

As can be deduced, it has several stepper motors and several circuit boards.

Image of what the main board with the DC input looks like

Another image of the main board

A photo of one of the motors

A troubleshooting video showing the DC board among other parts: https://youtu.be/aNqq-6n_vqs?t=836

A teardown video: https://www.youtube.com/watch?v=ergcvPaaVwk

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    \$\begingroup\$ It depends on the device, what is it? \$\endgroup\$
    – JaySabir
    Aug 11 '20 at 7:48
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    \$\begingroup\$ The person selling the item says that the voltage will basically adjust itself based on the device being powered That is a dubious statement in my opinion. In my opinion, whoever said this has no clue. If the 18 ~20 V adapter is OK for your device depends on the device, realize that trying while the device cannot handle this voltage, can damage the device. I would simply get an 18 V, 2.5 A (or more than 2.5 A) adapter, pay attention to the polarity and use that. I would not use the 18 ~20 V adapter, to me it looks like a very cheap, poor quality adapter. \$\endgroup\$ Aug 11 '20 at 7:53
  • \$\begingroup\$ @JaySabir The device is a desktop cutting machine (like a printer, but cuts instead of prints). Here's a link: cricut.com/en_us/machines/cricut-explore-air-2.html \$\endgroup\$
    – B B
    Aug 11 '20 at 7:56
  • \$\begingroup\$ @Bimpelrekkie I would have preferred an 18V brick as well, but to be honest, that's the best looking one I found. the others are basically iterations of this adapter from aliexpress costing less than 10 USD aliexpress.com/i/32992033664.html \$\endgroup\$
    – B B
    Aug 11 '20 at 7:57
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    \$\begingroup\$ So I guess the 18V~20V is basically a bug, not a feature. That makes more sense. And yes, I think the seller may have said that "auto-adjust" statement out of lack of knowledge. \$\endgroup\$
    – B B
    Aug 11 '20 at 8:02
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The power supply cannot adjust itself automatically to what the device expects. It can adjust the output voltage to try to compensate for the voltage drop on the wires based on current draw though, but the original is only rated 2.5A and the replacement is rated up to 4A. Get a proper 18V replacement, with 2.5A or more current rating.

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  • \$\begingroup\$ I agree on getting a better suitable adapter. \$\endgroup\$ Aug 11 '20 at 7:54
  • \$\begingroup\$ Unfortunately, current options are limited to that one I posted or aliexpress "universal adapters" aliexpress.com/i/32992033664.html which look much flimsier. I would probably have a replacement shipped from the manufacturer, but that would take too long. \$\endgroup\$
    – B B
    Aug 11 '20 at 8:00
  • \$\begingroup\$ It can adjust the output voltage to try to compensate for the voltage drop on the wires based on current draw though i'm trying to parse what this means. Does this mean that voltage can increase based on the amount of electricity the device is using? \$\endgroup\$
    – B B
    Aug 11 '20 at 8:10
  • \$\begingroup\$ It is possible. But you don't have a datasheet that tells you how it works. Don't buy anything unless you know how it works. If the old adapter has a 3 prong grounded mains input and the output is also grounded, do not buy an ungrounded power supply. You risk damaging something if the device has any external connections to computers or other devices. \$\endgroup\$
    – Justme
    Aug 11 '20 at 8:13
  • \$\begingroup\$ Apart from checking a data sheet, is there any other way to check output voltage? Would it be best to just purchase a multimeter to test, if that's what's necessary? Or would it still be unsafe? I'm sure they can let me test the adapter while plugged before purchasing. \$\endgroup\$
    – B B
    Aug 11 '20 at 8:20

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