# Electronic Voltage drop without transformer



## jaxmwana (Nov 29, 2009)

Alright guys... I'm a little new to this forum so happy to join all of you 
I'm currently building an emergency lighting system and need a little help. I would like to use a circuit that would drop the mains power supply from 230V to about 7V. Only problem is I do not want to use a transformer, so would like to use some kind of voltage regulator. Any ideas how I could do this? I would appreciate it if I received some feedback. thanx


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## AussieApprentice (Aug 16, 2008)

What size load?
Do you want AC or DC?


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## Bob Badger (Apr 19, 2009)

Can I ask why you would want to drop to seven volts?

Voltage drop is going to make that a costly choice.

Your conductor sizes will end up very large to distribute 7 volts to lighting fixtures.


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## Speedskater (Oct 2, 2009)

First, have you covered all the safety issues and rules about having your unit connected directly to 230V ?

If your unit draws a constant current, you can use a resistive voltage dividing network.


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## jaxmwana (Nov 29, 2009)

thank you for all the replies.... 
output voltage is DC. I was thinking I would smooth this and regulate it further to give a more steady output. To put it this way, I would like to drop the mains to about 30-40 V by some kind of electronic ballast. And then use a switching regulator, but I have no idea how to construct the ballast. It was just an idea. Lets say, if money wasn't a factor, how would I go about this?


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## Speedskater (Oct 2, 2009)

_Lets say, if money wasn't a factor, how would I go about this?

_*This is a very dangerous project!* It will require UL approval to do it safely. (and UL approval is not cheap)

But the circuit only needs a handful of resistors, capacitors a bridge rectifier and maybe a zener diode and voltage regulator.


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## John (Jan 22, 2007)

jaxmwana said:


> thank you for all the replies....
> output voltage is DC. I was thinking I would smooth this and regulate it further to give a more steady output. To put it this way, I would like to drop the mains to about 30-40 V by some kind of electronic ballast. And then use a switching regulator, but I have no idea how to construct the ballast. It was just an idea. Lets say, if money wasn't a factor, how would I go about this?


No use reinventing the wheel. :blink:

How about a 36 VDC battery charger for $299.99. With a bit of electronic tinkering you get 36 VDC.:thumbup:

http://www.hgrindustrialsurplus.com...SC=&pageSize=50&currentPageIndex=0&searchNAP=


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## Joshua (May 13, 2009)

*Electronic voltage drop*

**EDIT: I just read that you were already dropping it to an intermediate voltage. Again, I would still recommend a switch mode power supply or some sort of bucking arrangement with inductors. What kind of current does this draw?

I agree with some of the other poster's on this, why 7v? Will you be distributing this to a wide area circuit or is this an individual device? If this is for many devices, each one should probably have it's own supply, or you should at least supply them with a larger voltage (12-36VAC) and regulate in the device. 

I am guessing you do not want a transformer because of it's size? The only thing that comes to mind is a voltage divider with resistors, or some mix of diodes and resistors. Other than that, you could use a switch mode power supply (though those do have either small transformers or inductors).

Honestly, if you are installing this in a building, I would look for a pre-made, UL (or other regulatory agency, I believe you're from the UK) item to do this; it is probably cheaper and much safer. Having been an electrician and now nearly done with my electrical engineering degree, I would just buy it...sure I could design a power supply for a device, but when push comes to shove, it is much easier and usually cheaper to just buy a pre-made unit.

Any details you can give about this project of yours I'm sure would help discussion.


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## jaxmwana (Nov 29, 2009)

Yeah, the reason I do not want to you use a transformer is for its size and power consumption. this is a download link to the circuit I am building

http://rapidshare.com/files/314801945/Circuit.jpg.html

The main aim is to reduce the power consumption of the circuit. The fluorescent tube uses about 8W of power and the circuit about 7W. I have already decided to use a different light source using LED's but Would like to improve it further by getting rid of the transformer. Maybe this post will help? cheers


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## Wobbly Head (Nov 7, 2009)

There's a big difference between electrics and electronics one you try to stay grounded to prevent damaging equipment the other you don't want to be grounded to prevent damaging yourself. Go for a off the shelf emergency light system it will be safer.

Also half the circuit in your download is a rectifier circiut feeding both a flourecent fixture and a battery charger all changing from a flourecant light to a LED system will save around 6W-7W but you will still have 7W for a battery charger and actual line losses in a transformers are very little especialy on a low power application.

It would be helpfull to know the actual application 7V seems a odd voltage I have never encountered 7V systems in both working in electronics and being a Electrician.


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## energysmartin (Dec 8, 2009)

ESI Led lighting system for savings money and energy.


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