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How to reduce voltage from 277VAC to 120VAC with out using Transformers

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pkcharan

New Member
Hi,

I am new to Electronics Industry.

I had an application where I need to use 120V rated Incandescent bulb(50W) in 277 Volt supply.

Presently I am using a step down transformer to knock the volatgte down to 120V but the problem is its making humming noise.

So I was looking for Electronic Voltage Reducer that knocks voltage from 277VAC to 120VAC I tried searching through internet but I could not find any .

I have seen boards that reduce voltage from 120V to 24 V using resistors.

Can any one help me where I can find such products or information.


Thank you

Kalyan
 

tcmtech

Banned
Most Helpful Member
capacitive couple the bulb. Just put a specific size capacitor in series with the bulb. You will have near 100% efficiency and no noise.

TO power a 50 watt bulb at 50 Hz from a 277 volt source you would need a 8.4 uf AC capacitor. At 60 Hz you would need a 7 uf capacitor. A little less will just make the bulb a bit dimmer.

Standard power factor correction/motor run capacitors or a HV non polar capacitor like a mylar or poly type will work too. Just not an electrolytic!

Just make sure it has a 250 VAC rating or higher.
 

pkcharan

New Member
Thank you for the replies and information.

Do you know any company/ website that makes these boards or products using

capacitators/resistors to knock down the volatage.
 

tcmtech

Banned
Most Helpful Member
Any on line electronics supply company would have them. The capacitor method I mentioned would only cost a few dollars. Mouser, Digikey, Allied, and MSC. These are my most often used electronics and power equipment sources.

With out knowing where your located we cant say exactly what dealer is nearest to you or your region.
 

Hero999

Banned
A 120VDC universal input SMPS will work because it doesn't matter whether it's AC or DC.
 

pkcharan

New Member
Thanks for the response.
Do you know any one who makes the complete board/box with capacitors or any custom electronics that makes boards/ box to reduce volatges.
 

restavation

New Member
Variation on a theme

Hello all,

Found this thread looking for an answer to a similar question. I need to feed two historic ceiling fixtures designed to take medium based incandescent lamps and want to use the 277VAC night/emergency circuit. Would any of the solutions suggested also work for CFL's?

Thanks,
PTR
 
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