I have a dehumidifying cabinet which requires 5V 900mA, and I have a universal adapter that is rated at 1000mA 12V, however the slider doesn't have a 5V marking, only 4.5 and 6V. Is it okay to point the slider to somewhere between 4.5 and 6 in hope of getting around 5V?

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    \$\begingroup\$ Can you give us a link to information about the adapter? \$\endgroup\$ – tyblu Dec 23 '10 at 1:50
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    \$\begingroup\$ Do you have a multimeter you can use to check the output? \$\endgroup\$ – myron-semack Dec 23 '10 at 3:01
  • \$\begingroup\$ I just realized that a user needs a certain minimum rep to be able to comment -- not sure if chuanose can even reply to us! So.. +1! \$\endgroup\$ – tyblu Dec 23 '10 at 16:05
  • \$\begingroup\$ Just thinking about this, what engineer on the planet earth would design a universal adapter that offers selections of 4.5, 6 and not 5!? I'm guessing it's a switch based unit and they switch in and out a small set of resistors in the regulator feedback where some combination gives 4.5 and 6, and God forbid they spend 3 cents on a separate resistor for 5. \$\endgroup\$ – bt2 Dec 28 '10 at 0:25
  • \$\begingroup\$ it's probably designed to replace an integral number of 1.5v cells \$\endgroup\$ – Chris Stratton Dec 28 '10 at 4:26

If the slider is a switch, then you won't be able to set the output to an intermediate value (5.0V). The only way that you would be able to get a 5.0V output is if the slider is a linear potentiometer, although I find that unlikely.

It's more likely to be a switch because switches are cheaper and don't require calibration for specific positions (4.5V, 6.0V, etc...). It may still work at the 4.5V setting, depending on the electronics since 4.5V is only -10% from the specified voltage.


NO, depending on the type of switch and the design of the circuit - the output could be either much lower, 4.5v, 6v or a lot higher.

There are different ways of controlling a regulator with a switch

and there are 4 possible answers... A) Both 4.5v and 6V Inputs are selected at once B) 4.5V Input Selected C) 6V Input Selected D) No Input Selected

B and C are harmless. - Just the same a normal use.

A and D cause problems - if both are selected or neither are selected - depending on the design this will cause either a higher or lower voltage - it is impossible to guess without more information... and could cause damage to the unit.


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