dimmer
- Thread starter aliasghar
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- Location
- Massachusetts
Re: dimmer
Any new dimmer will save you money as it does cut down the power consumed.
I believe that old rheostat type dimmers did not save energy, they dimmed the lamp by converting some of the power to heat.
Any new dimmer will save you money as it does cut down the power consumed.
I believe that old rheostat type dimmers did not save energy, they dimmed the lamp by converting some of the power to heat.
- Location
- Massachusetts
Re: dimmer
A 100 watt, 120 volt lamp at the end of a very long circuit, the long run reduces the voltage at the lamp to 75 volts.
The reduced voltage reduces the power consumed by the lamp.
Does the circuit draw less energy through the cash register?
Let me ask this.
A 100 watt, 120 volt lamp at the end of a very long circuit, the long run reduces the voltage at the lamp to 75 volts.
The reduced voltage reduces the power consumed by the lamp.
Does the circuit draw less energy through the cash register?
physis
Senior Member
Re: dimmer
Let me use some easier numbers.
100 watt bulb. 120v. It's resistance is 144 Ohms.
With no series resistance it uses:
120/144=.833 amps. or 100 watts.
Add the resistance of one more light bulb in series. now the total resistance is 288 Ohms.
120/288=.416 amps or 50 watts
The power is reduced to half. And half of that is being wasted as heat in the 144 Ohm resistance. So you get 1/4 of the original power as light while using 1/2 the original power.
This ignores the filiment temperature of course.
Let me use some easier numbers.
100 watt bulb. 120v. It's resistance is 144 Ohms.
With no series resistance it uses:
120/144=.833 amps. or 100 watts.
Add the resistance of one more light bulb in series. now the total resistance is 288 Ohms.
120/288=.416 amps or 50 watts
The power is reduced to half. And half of that is being wasted as heat in the 144 Ohm resistance. So you get 1/4 of the original power as light while using 1/2 the original power.
This ignores the filiment temperature of course.
physis
Senior Member
Re: dimmer
Aliasghar,
I'm going to answer you new question here.
The way dimmers work now-a-days is by switching a semiconductor device on after a portion of the AC sine wave has passed. Essentially, it's a switch that is turned on and off so fast that you can't tell.
Editted spelling
[ February 08, 2005, 01:30 PM: Message edited by: physis ]
Aliasghar,
I'm going to answer you new question here.
The way dimmers work now-a-days is by switching a semiconductor device on after a portion of the AC sine wave has passed. Essentially, it's a switch that is turned on and off so fast that you can't tell.
Editted spelling
[ February 08, 2005, 01:30 PM: Message edited by: physis ]
- Location
- Massachusetts
Re: dimmer
It turns out there was no helping me I was just plain wrong.
Well I learned something.
Bob
OK you got me, I even asked around for some help on this one.
It turns out there was no helping me I was just plain wrong.
Well I learned something.
Bob
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: dimmer
If applied voltage stays constant and amps decrease you have lower watts
If applied voltage stays constant and amps decrease you have lower watts
Re: dimmer
A rheostat reduces the current, hence the power is less.
A duty cycle modulated circuit such as a modern light dimmer also reduces the current but in a more efficient, but noisy, way.
The lamp itself, running at a lower temperature, is less efficient. Sort of like using a bathroom heater for light which I have done in the middle of the night.
[ February 08, 2005, 09:39 PM: Message edited by: rattus ]
A rheostat reduces the current, hence the power is less.
A duty cycle modulated circuit such as a modern light dimmer also reduces the current but in a more efficient, but noisy, way.
The lamp itself, running at a lower temperature, is less efficient. Sort of like using a bathroom heater for light which I have done in the middle of the night.
[ February 08, 2005, 09:39 PM: Message edited by: rattus ]
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