Question about power - volts, amps, watts

[Duer 157099]

I want to finally, once and for all, understand this. It has to do with figuring out which power supply (as in AC transformer) to use for various electronics.

For example, I have an LCD monitor that seems to have a bad transformer. Since I'm going to have to spend $15-20 for a replacement, I figure I want to get the most flexible one, a universal, so that if I need to, I could use it for other things.

This particular monitor power specs are: 18v 3.33a (59.94W).

So... if I find a universal that has an 18v option, but the amperage is 3.5, is that ok or will I blow something? (I only know that basic of basics about such things)

Or, can I go with any combo as long as the output wattage is equivalent? Which is the critical number, the volts? If I can't get exactly what I need, which side do I err on?

Also, in the meantime, what happens if I try to power it on using another transformer I have from another device, but which is either higher or lower? If lower, is the only risk that it just won't work, but higher I might blow some components?

Any simple explanations, so I don't burn the house down?

[madokie]

1. Higher voltage or lower voltage is a no no

Voltage is what you want to match. The amps or watts the monitor uses is determined by that device so your power source needs to have at least that amount. So you need a power source for that particular monitor that is rated at 18 volts and at least 59.94 watts, a higher wattage rating is of no concern. If the transformer is rated for more watts or amps that is no problem as the monitor will only draw whatever it uses. The specs on the transformer is only what it is capable of providing.
Hope that makes sense to you. The voltage is real important to match

[Duer 157099]

2. Thank you! Yes, it makes sense

So as long as I get one that has an 18V option, the amperage doesn't really matter, as long as it's more than 3.33... so that the wattage is at least 60watts.

That really helps! I have sooooo many orphaned transformers that I never know if I can use for other things unless they're an exact match. Now I know!

Really appreciate it! :thumbsup: :toast:

[MyNameGoesHere]

3. Also make sure the center pin polarity is correct.

They usually say center pin positive or negative.

[Duer 157099]

4. Yes, thanks n/t