Quick 18A @ 2 volt power supply needed
Hulk
Posts: 68
I could design this power supply with a 2n3055 if it could handle the current, but I'm seeing 15 amps as a max and that's at a die temp of 25 degrees C (which will never happen). I have a bunch of hexfets (IRFZ42) and an ATX power supply.· The ATX can supply around 20 Amps on its 3.3 volt (orange) line and 25 amps on its 5 Volt line.
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My problem is my lack of knowledge of FET power supplies.
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I·have a friend that teaches jewelry design and needs a power supply where you set the voltage somewhere between .5 and·2 volts and immerse a nonconductive thing like a flower seed pod in a solution of some copper compound and the copper builds a thick layer on the object and it looks really cool.· The key·to the process is a proven method of depositing a sprayed silver conductive layer on the, otherwise, nonconductive nature thing.
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So, my stamp friends, can you show me how to use wiz bang hex FETs to design a voltage-controlled power supply using my 3.3 or 5.0 outputs from ATX power supply that will supply a max current of 18 amps·to a plating solution?
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BTW, I've gotten past the tricks to keeping the computer supply active so I don't need that help.
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I will be grateful for any help you can provide.
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My problem is my lack of knowledge of FET power supplies.
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I·have a friend that teaches jewelry design and needs a power supply where you set the voltage somewhere between .5 and·2 volts and immerse a nonconductive thing like a flower seed pod in a solution of some copper compound and the copper builds a thick layer on the object and it looks really cool.· The key·to the process is a proven method of depositing a sprayed silver conductive layer on the, otherwise, nonconductive nature thing.
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So, my stamp friends, can you show me how to use wiz bang hex FETs to design a voltage-controlled power supply using my 3.3 or 5.0 outputs from ATX power supply that will supply a max current of 18 amps·to a plating solution?
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BTW, I've gotten past the tricks to keeping the computer supply active so I don't need that help.
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I will be grateful for any help you can provide.
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Comments
I know that's the best and most efficient electronic solution, but the bulk of that function is handled by a single chip dedicated to that function on the input to the high frequency transformer. I'm looking for a simpler series regulator circuit to be added after the stable circuit that's already there. I'm basing my request on a circuit like an emitter follower where you supply a variable voltage to the base of a power transustor like the 3055 and you see that voltage (minus about .6) at the emitter. I'm sure there's a simple hex fet solution, but I havent found it yet.
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That sure looks like a source follower. I didn't know it was so similar to the emitter follower that I was familiar with.
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BTW most industrial electroplating I have seen is done with a constant current source to control the current per unit area of the item to be plated so a couple of 3055's in parallel with .01 ohm emitter resistors might have been a better way to go.
The lady that wants to do this gave me an article from a trade publication. It states some empirical study is necessary to get good results and bases their control on the source voltage rather than the current/area. I, like you, would have expected controlling the current at a constant level based on square inches covered, but that's not the way the article is written.
I've done some platting and some anodizing so could be considered as "experienced" (certainly not an expert), but I will stick with her source until I can demonstrate that current control works better.
Thanks for your help and advice.
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at different voltages...there are plans on the web, just google.
I did it once to get 13.8v from the 12v line...it involved rewinding the
small transformer inside and took about an hour.
Perhaps a similar project could drop the 5v line down to 2v?
will drop the voltage closer to 2 volts. It is probably easier to find a high current bridge rectifier than diodes rated
over 20 Amps.
I have one of those cheap panel meters that reads 0 to 2 volts and thought I would read the drop across the ground lead using a second (Kelvin) lead on the ground supply lead; this to measure current. I'm shooting for .001 ohm which should yield .020 on the el cheapo meter (@20 amps) and I can wire it to put the decimal point in the right place. Given .00118 ohms per foot of 10ga wire, i figure I can use a pair of parallel leads 20.3 inches long (and a third Kelvin lead) to read th IR drop to get the current. Does that sound like a good plan?
Naturally, I can switch the + meter lead to the + power supply lead to get the supplied voltage (and move the decimal point at the same time).
BTW, this is a different kind of plating process than usual (for me anyway). You can plate an object like a flower pod by first spraying it with a conductive paint. Then the copper in the solution plates itself onto the seed pod. I've seen some successful results from equipment that costs about 800 bucks so this will be a good deal for her jewelery school if she/we can pull it off. When the part is fully covered, you heat it and burn out the original organic material and this leaves a very sturdy hunk of copper.
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