How to build a 110V voltage regulator?

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Thread Starter


Joined Oct 12, 2010
I need to create a device that will do the following:

It will accept an input of 110~120V AC

An appliance will be connected to it (TV, Fridge, VCR, DVD Etc)

When the device senses a drop in the input voltage, will cut power to the appliance, and wait a few minutes until the voltage stabilizes and then close the circuit again to allow the appliance to work.

I need to build something like this because I live in a country where power fluctuations are very normal and I want to protect my home appliances.

Please, I cant get a battery backup or a proffessional voltage regulator, I need to buid this myself and cut down on all cost.

I am not electronic inclined so be easy with the explanations, Please.

Thanks a lot for your help.


Joined Sep 21, 2010
Posted a picture of what you described, It is designed for 240V ac so you may be able to change it to 110V ac It was an electronic Kit here in AUS some years ago @ SILICON CHIP on lineBuild a brownout protector. Daryl



Joined Jul 17, 2007
I am sorry, but projects involving control of mains power directly by novices is an invitation to disaster.

I do appreciate and am sorry for your predicament. However, you have a great deal to learn before even considering such a project.

I don't know how much UPS supplies cost where you are, but here in the States they can be purchased for under $100 USD, which is a fraction of what a HD TV or computer costs. Such a UPS would be adequate for perhaps a TV and DVD, or a single computer. If you had the money to buy all of these devices, you must also have enough money to buy UPS'es to protect your purchases.

Refrigerators use a great deal of power; anywhere from 600 to 1500 Watts. It is not practical to operate such devices from uninterruptible power supplies, unless they are for medical purposes. However, if you are as novice as you claim, you would have to do a lot of reading before you could build an effective, efficient and safe circuit to protect your refrigerator.

Modern refrigerators do have some protections built-in; if the compressor stalls due to momentary interruptions in power, the motor will overheat and open a thermal breaker. The heating/breaker opening cycle will repeat a few times until the pressure has been bled off the high-pressure compressor out side; then it will again run normally and keep your food cool.
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