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stupid newb question RE: capacitors

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kevinnku20

New Member
Hi all,

I'm going to preface first that I am fairly certain that I understand that this won't work but am more intrested in the "why" than I am the fact that it won't work. Anyway here goes...

I just purchased a laser printer, it causes the lights to flicker when firing up and printing... I know the real solution to the problem is to run a new circuit, however in my house (new construction < 1 yr and heavily insulated walls everywhere) and the desierd location of the print, its just not feasable to run a new line.

Enter my curiosty and my just enough knowledge of electronics to set something on fire... Why isn't there an inline device on the market that is simply a bank of capacitors that stores enough energy for that initial draw such that it won't draw so heavily on the line. Surely I'm over simplifying this, and thats why I'm asking teh experts.

Whats the fundamental flaw with this idea? Is simply an incorrect use of capacitors or are there no cost effective capacitors on the market that would hold the voltage needed for this appiation?

Thanks in advance

Kevin
 

kchriste

New Member
Forum Supporter
Capacitors would work if your wall socket supplied DC, but it doesn't. A large electrolytic capacitor across the AC line would go BANG! :D
 

Bob Scott

New Member
Hi all,
I just purchased a laser printer, it causes the lights to flicker when firing up and printing... I know the real solution to the problem is to run a new circuit, however in my house (new construction < 1 yr and heavily insulated walls everywhere) and the desierd location of the print, its just not feasable to run a new line.
Kevin
There is something very wrong with the power wiring in your house if the lights flicker from variations of current draw from your computer printer.

I hope your house has a new home warranty. What country?

Bob
 

Diver300

Well-Known Member
Most Helpful Member
Look at the power supply voltage rating of the laser printer.

If it is something like 100 - 240 V AC, 50 - 60 Hz, then the power supply will almost certainly be a switch mode power supply. Then you can run it on DC without any problems.

You can rectify the mains and put a large capacitor across the output, and run a switch mode power supply from it. You would probably want something to limit the turn-on surge when you first charge the capacitor.
 

whiz115

Member
Why isn't there an inline device on the market that is simply a bank of capacitors that stores enough energy for that initial draw such that it won't draw so heavily on the line.
also have in mind a large bank of capacitors could also initally draw huge enough amount of current and it will be like short circuit for your mains...

i'm saying this in case you come up with the idea of using bipolar capacitors to overcome the obstacle kchriste said... :)
 

Diver300

Well-Known Member
Most Helpful Member
You can limit the turn on surge with a resistor that is shorted out when the capacitors are charged. Alternatively, there are thermistors that start off at a high resistance to limit the current, then warm up and their resistance lowers.

Either method can also be used on AC, for devices like transformers that can trip breakers when they turn on.
 

Pommie

Well-Known Member
Most Helpful Member
No way should a printer cause your lights to dim. I would get your wiring checked.

Mike.
 

School

New Member
If it's not too big of a printer, plug it into various receptacles throughout the house.
If it does the same thing on every outlet, chances are the printer has issues.
 

audioguru

Well-Known Member
Most Helpful Member
Maybe the wiring from the street to the home has a resistance that is too high.
 

RCinFLA

Well-Known Member
I have seen this effect on flourescent lights on same extention cord as laser printer. I think it is caused by surge pulses from the HV electro-static generator.
 

phoenox

New Member
I had the same problem trying to use a laser printer and a desktop comuter at the same time. Running off a small generator, every time I tried to print something the computer would reset.

I used a battery backup(12 V battery + inverter) from radio shack to fix it. You may be able to find one that can handle the laser printer current.
 

smanches

New Member
I agree that it should not be dimming the lights. How many devices do you have on that same circuit? Why are the lights also on a receptacle circuit in a new house?

Something is wrong with your wiring.
 

crutschow

Well-Known Member
Most Helpful Member
The momentary high current is for the toner fusing heater. It heats up the paper to fuse the toner on the paper. That's why the paper is warm as it comes out of the printer.
 

AlainB

Member
In my old laserjet III printer, it is what look like an halogen lamp (600 watts, more or less) that provide the heating for the toner fusing unit. It goes on and off as needed but at least a few seconds in each state.

If Kevin's lights are dimming while printing, I would guess that this particular circuit is overloaded. But if they are flickering a few times a second it could indicate a bad connexion arcking somewhere.

Would be nice to know the location when talking about main voltage.
 
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