# Modified microwave transformer- rneed advice for rectifiers and wire ratings.

1. Mar 31, 2012

### Cu_extractor

Modified microwave transformer- need advice for rectifiers and wire ratings.

Hello everyone. I've been doing a lot of research as to how to go about purifying copper. There are two approaches I'm considering. Electrolysis and Smelting. The electrolysis method requires I have a DC output of low voltage and high amperage.

I'm in need of the high amperage as amps relates to coulombs, as coulombs relates to the amount of moles of electrons I can get. I've calculated I can get around 18.65 moles of electrons per KWh from 500 Amps. Here's my calculations for my electrolysis procedure,

(500 Amps (Coulombs)) * (6.24 E18 electrons) * (3600 seconds) / (6.02 E23 particles) = 18.65 moles of electrons per kilowatt hour.

So, by modifying the secondary coil of a microwave transformer rated somewhere around 1000 Watts, I should be able to produce 2-3volts at 500amps. This transformer is being fed from a regular residential outlet, (120V 20A). My problem arises when I've converted over to 500 Amps, it's still in AC current when I need DC current to correctly carry out electrolysis. I'm not sure where to find a cheap rectifier that can handle something like this, and, would I need something to protect the overall device from overheating?

As for smelting of the copper, I like the design this person came up with in this youtube video: http://www.youtube.com/watch?v=zw_SrGU2iYs&feature=relmfu

All I need is some furnace cement and some kind of wire that could handle the temperatures needed to melt copper. My modified transformer's output can just stay in AC, and I'm basically using an induction heating coil. If I were to go to a junkyard, could I expect to find the type of wire used in this video within a certain device?

Thanks, any help is appreciated!

Last edited: Mar 31, 2012
2. Apr 6, 2012

### Kurinn

Well, just at a glance your math looks okay.

About the rest of your idea, I'm not so sure. Working with wet, conductive stuff, and hundreds(!) of Amperes of AC is not my ideal afternoon. I really hope you have some notional understanding of what I'm talking about when I say that this would be Bad News Bears as far as safety is concerned. I'm not even sure if using a GFCI outlet would help you if you messed this up, but I know very well that such current could easily kill someone.

If this is your first attempt at electrorefining, I really think you should start out smaller and work your way up incrementally. That way you can get a good grasp of your electrolyte balance and electrode setup without the consequences of making a mistake being so deadly. You can buy power supplies pre-made that can be adapted to provide a decent amount of current at as low a voltage as you want. Starting out with a jury-rigged microwave transformer pushing 500 Amps isn't a good idea. Don't do it, unless you have an electrician and a paramedic team standing behind you and a solid piece of plexiglas.

Also the inductive heating thing isn't so simple either. They run at high frequencies (think kilohertz), and usually require a lot more circuitry than a transformer and a rectifier. Also not a good starting point.

3. Apr 6, 2012

### Bobbywhy

Cu extractor, Welcome to Physics Forums!

You posted that you want to purify copper by two methods, one of them is the "electrolysis method requires I have a DC output of low voltage and high amperage." Transformers do not produce DC outputs. Rectifiers capable of producing 500 amps are not cheap.

As Kurinn warned you above, this kind of amperage can be DEADLY! Whenever anyone asks about a dangerous activity here on Physics Forums it is prohibited. This is because folks like you who do not know what they are doing sometimes injure themselves and or die. PF will not be party to any of this. Read the Rules and posting guidlines.

As for the smelting part using induction heating (as in the youtube video) you could not use that microwave transformer to power an induction heater. Kurinn above reminds you that induction heaters operate in the kilohertz region. How does one obtain that kind of frequency and power? You will need to learn the details of induction heating first.

4. Apr 7, 2012

### vk6kro

As Kurinn warned you above, this kind of amperage can be DEADLY! Whenever anyone asks about a dangerous activity here on Physics Forums it is prohibited. This is because folks like you who do not know what they are doing sometimes injure themselves and or die. PF will not be party to any of this. Read the Rules and posting guidlines.

There is no problem with a transformer capable of 500 amps, unless its voltage is more than 40 volts or so.
This poster mentions 2 or 3 volts.

It would be capable of a lot of heat generation but it is the voltage across you that will cause electric shocks.

The only real problem would be with the mains connection to the primary, which we have to assume has already been done safely. Once the high voltage winding has been removed it should be safe enough.

Some microwave oven transformers tend to overheat due to low primary winding inductance. So, they should not be used for prolonged periods.

5. Apr 7, 2012

### Staff: Mentor

Re: Modified microwave transformer- need advice for rectifiers and wire ratings.

Cu_extractor, I'm curious to know why you are wanting to purify copper in quantity. Experimenting with a small amount I can understand, to prove you can make it work, but why apparently large amounts?

6. Apr 7, 2012

### jim hardy

A propane smelter migh be easier to build. If you have copper salts dissolved in water that get into local groundwater you might be asking for trouble.

Search on "Babbington Burner " , works great on used motor oil.