Power adapters

[Thorn_veritas]

As some of you might know I recently hotwired my 1500w hotplate to run full power all the time but on a spiriy run I think its a bit high. I was thinking if I but 1 of those power adapters to swap it to a american style plug ie 110v would that halve my watts? Im just a little curious thats all


Thanks for any help.

[rad14701]

The simplest way to halve the current flow to your hot plate would be to use a properly rated diode... When used in combination with a bypass switch you would have two power settings, 100% and 50% mains power... You'd have 50% when running through the diode and 100% when running through the bypass switch... Again, all components would need to be properly rated...

[Dnderhead]

if you cut the voltag in half that lowers the wattage by 4. so if using a 240 v ,1500w hot plate.
on 240 you have 1500w on 120v you will have 375w.

[rad14701]

The debate over whether the power gets halved or quartered is a common one... Dnderhead's post caused me to go look into this yet again... It seems that even the electronics forums cannot agree on this one, nor can my electronics calculation spreadsheet... But here is the logic...

When using a rectifier diode in an AC circuit you are only blocking one half of the AC sine wave... This remaining half is still operating at 100% voltage and 100% amperage, just for half as many pulses in a given period of time... So the circuit is putting out 1/2 of what it would without the diode, in full wave operation... Well, actually within .6V of half because of the power consumption of the diode... We still have full mains voltage... We still have the same resistance... So we still have the same amperage... Which means the same wattage per pulse... But we only get it 60 times per second instead of 120 times per second for 60 Hz AC, or 50 instead of 100 for 50 Hz AC... The AC sine wave goes from zero to 100% in each direction, not from zero to 50% in each direction... Hence, 1/2 the wattage from half as many pulses...

I have a love/hate relationship with electronics...

[Dnderhead]

I'm not an expert on electrical. but using a diode .you block 1/2 of the wave,say everything
above 0. with ac you have 1/2 above and 1/2 below 0. so (say with 120v)
you have 60v positive and 60v negative.now when using a diode you are using just 1/2
(the peaks above or below 0) there for you are using just 1/2 or 60v..
now with some of the controllers you "chop" the first part of the wave (depending on how it is set)
there for you still can have 120v but less current.this happens because the peeks can still be there.other controllers "chop" the tops of peeks off,there by limiting the voltage.

[rad14701]

Dnderhead, read this topic and this topic for more information... Read them from start to finish... Like I said, even those who dabble in electronics more than I do have a hard time agreeing on this...

[rad14701]

Just to help clarify, without beating this into the ground, I just did a quick test during a TV commercial break...

I used an extension cord, a diode and, a multimeter to do a test a 120V circuit... Using the multimeter leads, in one direction I got ~117V AC and in the other I got ~8.6V AC... So using a diode I was still getting full mains voltage, not half... Therefore, with a given resistance I would get a predicted amperage, based on Ohms Law... However, I should only expect to get just over half the wattage compared to the same circuit sans diode...

This statement, from allaboutcircuits.com, in the review section, almost says it all...

A diode is an electrical component acting as a one-way valve for current.

Notice that it states "current", not "voltage"...

Now, after all of this, we still need to remember that there could be some EMI/RFI issues when using a single diode under the extreme loads of a heating element...

[maheel]

As some of you might know I recently hotwired my 1500w hotplate to run full power all the time but on a spiriy run I think its a bit high. I was thinking if I but 1 of those power adapters to swap it to a american style plug ie 110v would that halve my watts? Im just a little curious thats all


Thanks for any help.

Hey T-V you dont mean one of those plugs you buy at the airport to change the "pin" shape on the plug do you ???

thats not going to work....

even a step down transformer will need the right watts - amps rating to handle the juice you want

build a PSR-25 buddy, you will not look back i reckon