# Ideas on building a rectifier / transformer



## SilverNitrate (Jan 31, 2009)

Any ideas on building a home-made power rectifier out of easily obtainable sources for powering electro-refining setups. 

Parts from an old microwave oven, computers, copy machines or spare cell phone chargers could possibly be used. 
Stepping down and rewiring transformers to required voltage and amps for stripping metals etc.


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## Anonymous (Jan 31, 2009)

SilverNitrate said:


> Any ideas on building a home-made power rectifier out of easily obtainable sources for powering electro-refining setups.
> 
> Parts from an old microwave oven, computers, copy machines or spare cell phone chargers could possibly be used.
> Stepping down and rewiring transformers to required voltage and amps for stripping metals etc.


Help yourself (256,600) google hits on modifying old computer power supply's.

http://tinyurl.com/ae6d6j

You may also want to read my previous post on multi linking PSU's
http://tinyurl.com/cffmaq


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## SilverFox (Feb 1, 2009)

A rectifier is just four diodes, to change AC to DC.

they are easy enough to make.

Although, I find your standard battery charger with variable amps is all the Juice your going to need.

if your using any motors, 12 volts is pretty standard, plus you may just end up spending the 50bux in modifying a power supply.


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## SilverNitrate (Feb 1, 2009)

I'd like to see pictures posted too. I know to electrically purify copper you need a power of less than .5 volt with high amps. I think there is a way to do it using old transformers, but what sizes and how to wire them to get low volts with high amps from a 120/240 volt AC source.


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## butcher (Feb 1, 2009)

ok you asked for it now here I go:
first you need to decide what you need and how fancy. 
you can use just battery,s and maybe a charger for them, or lets get fancyier.
we need current according to the size of cathode (current density) depending on the size of your cell and cathode area, these will need to be decided and caculated, also consider if plating or electrowinning and if you are going to use a single, series, or parralel plating setup, your voltage will usually be low DC voltage.
the better the regulation of voltage and current(AMPS) the better our results will be.
so we need a transformer to step down the voltage these are alternating current we need low voltage direct current and regulated.regulating voltage and current.
lets look at options we can control the primary of transformer to lower the secondary voltage output, this can be done with taps in winding turns of primary and a switch, or better a variac ( varible transformer)also called(varible autotransformer) they usually look like a large doughnut wound coil with a carbon brush on a knob to dial up how much voltate it outputs, this will give our main transformer selected voltage and then it will give a secondary output accordingly.
another way to do this and more complicated but better regulation is with SCR's silicone controlled resistors , they have three terminals, a gate-anode and cathod , the current on gate controlls the anode to cathode current, wich in turn controlls our transformer which controls the output, the SCR will need a circuit for controlling of gate usuall with a feedback circuit.
so if you got this far lets keep going now we have a controll of voltage AC output what about current? well size of transformer and its wire can limit that, or maybe we want better control, we could use SCR's here again with another circuit to regulate current (SCR's also are like diodes current only goes through it from anode to cathode so that takes care of DC here). but this is getting a little more complicated so lets look at other options of controlling current, ok how about light bulbs them things put in series with our output will limit current, and with less waste than large resistors burning up our power as heat and the light bulb can be an indicator of our cell current showing us if our electrolyte is low on metals (ressistance of electrolyte, or we can use transistor circuits but there we go getting complicated lets just make this thing work ,
so now we have a regulated voltage and a regulated current (unless we went with SCR) we need direct current, to change alternating current to direct current we can use diodes, also called rectifiers, a single diode, but thats not good we cannot plate well, two diodes still not good enough, FOUR diodes, ahhh yes a bridge rectifier, this will give us more power and a smoother output, Ripple alot less. what you want it smooth well a large capacitor will do that so throw one of them on there, oh this is sounding easier its just a common power supply found in almost any piece of electronic equiptment but not in these new fangled computers they use switching power supplies, well we could use one of them but plating doesn't need to be that smooth, and we would not have the controll that we would with our homebuilt power supply and it probably would not hold up to plating for long,

so we now need specifications and ranges, for voltage current once we have decided on those we use OHMs law and a few other bits of math and caculate our parts sizes , we want this to last for along time getting our metals moved in our electrolytes, then we can search our junk bins for them parts and with a little solder and some old parts and slap one together put it in a box and some type of cooling circuit or heck just use those computer fans to get rid of the heat this thing disipates.
so lets start on a versitile supply for electroplating.
voltage range current range? cell sizes we want to use it on????
decisions decisions :roll:


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## peter i (Feb 1, 2009)

I just built one yesterday:


According to this neat little tutorial:
http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

It will deliver 3,3V/14 amps and 5V/22A, that's quite nice for a "costing next to nothing"-PSU.

I moved the blower to the outside, added some binding posts and a handle (and a blue LED to light the interior . 8) )

Best advise: RTFM! There are some constructional funnies about computer PSUs that you have to deal with. Ignore them and it will not work.


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## Anonymous (Feb 1, 2009)

Hi Peter
Thanks for that wiki link. Fix myself one up today, surprising simple.

Thanks
Jim


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## butcher (Feb 1, 2009)

ok going with a computer power supply? this only gives us a fixed smooth voltages and only two to choose from, and we have no current regulation either. well we still need to be able to change our plating or electrowinning voltage to desired output,( or just use 12 or 5 volt and live with results.
and we still need to be able to adjust or current for proper current density, and we have no regulation of current, (or use it as is and live with results,
and if we are able to adjust these as we plate or our solutions or our cell configuration change then we will have a versitile power supply.
well since we arent getting fancy you can use light bulbs to limit current, and voltage deviders to devide the voltage, 
or build a couple of electronic circuits to regulate voltage (to desired level & adjustable . and another portion of circuit to regulate the current to desired output. :?


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## butcher (Feb 1, 2009)

not a powersupply but some more technogarble on building tools, 
here's a couple of links on a simple induction coil heating furnace:

http://images.google.com/imgres?imgurl=http://webpages.charter.net/dawill/tmoranwms/Elec_SG3524Driver.gif&imgrefurl=http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat4.html&usg=__UJ34ggeQuCucMiwES_QyBlTPp-8=&h=240&w=446&sz=4&hl=en&start=15&um=1&tbnid=0xMwUNLCfMZMRM:&tbnh=68&tbnw=127&prev=/images%3Fq%3Dinduction%2Bfurnace%2Bschematic%26um%3D1%26hl%3Den%26sa%3DG

http://hackedgadgets.com/2008/11/25/diy-induction-heater/
need help understandin just ask questions there are enough of us here to help.


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## Anonymous (Feb 1, 2009)

My power supply has 12v, 5v, 3.3v, -12v, and -5v. You can make a few different voltages by combining these.
I do not think the - voltages are worth much since their combine amperage is limited to 1.2 amp.

As far as amperage limit you can use the plating area, electrolyte concentration, distances between electrodes to limit amperage.

Voltage can be set by using cells in series, ie 2 cells will half the voltage in each cell, 3 will be 1/3 of total voltage per cell, etc.

Jim


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## butcher (Feb 1, 2009)

you can run multiple cells and put them in series to lower voltage(the voltage devides and current the same).
you can have cellls in parralell to lower current(the current devides the voltage is the same).
or use a combination of both of these.
your cell size of cathode area will determine current needed (current density)
the plating metals and solutions can determine voltage neede.
as I said you can get by with this if you want to,
or with a little more effort build a regulated power supply. and more effort a SCR regulated supply that the modern plating industry are using.
or for that matter your battery charger a few light bulbs. its really up to what you decide.


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## Sylar (Feb 2, 2009)

butcher said:


> you can run multiple cells and put them in series to lower voltage(the voltage devides and current the same).
> you can have cellls in parralell to lower current(the current devides the voltage is the same).
> or use a combination of both of these.



This is only true if the electrical resistance of each individual cell is exactly the same. As soon as one of the cells deviate more then a few % it will cool down or heat up more rapidly because of higher/lower power input and change it's resistance even more in the wrong direction! Same goes for concentration of ions which also defines electrical resistance.

The only thing you can be sure of is when you put cells in series, that the exact same current goes trough each single cell, yielding equal deposition of silver.


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## butcher (Feb 3, 2009)

that is exactly why regulation and solutions are so important, thing change as it progresses and your power supply should also be able to change ,it really depends on your pupose for this power supply, and what kind of results you expect from it. personally if I build one would first go with variac, large transformer rewound secondary with switable taps, large diode bridge rectifier,large filter capacitors, and inductor filter, of coarse fuseing ,grounding and switch's....,. this will make it simple to build and versitile.


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## ki6ltp (Feb 5, 2009)

I use an astron 12 volt 15 amp variable voltage variable current power supply. You can buy one new for about 100 dollars. It works perfect for my cell plus there are benefits to using a power supply with variable voltage/current.


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## peter i (Feb 5, 2009)

ki6ltp said:


> I use an astron 12 volt 15 amp variable voltage variable current power supply. You can buy one new for about 100 dollars. It works perfect for my cell plus there are benefits to using a power supply with variable voltage/current.



Welcome aboard!

(Nice ingots you have there!)

And you are quite right. I have a restored lab. supply myself, and it is the one I use if control is needed.

Building the computer PSU is because it is cheap and fun, and will do some jobs just nice.


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