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Electrolytic Rust Removal Power Supply

Discussion in 'Power Electronics' started by David LaPierre, Oct 16, 2010.

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  1. David LaPierre

    David LaPierre

    Oct 16, 2010
    Hi everyone, I have a little project I've been working on and I could use some help as far as the electrical aspects of it.

    The idea is electrolytic rust removal, and the basic setup is this: A bin of water/washing soda with a rusty object submerged inside. The negative lead of a battery charger is attached to the object and the positive lead is attached to a piece of iron, in this case a rebar rod, which is also submerged in the water. This supposedly will de-rust the object without harming the unrusted metal.

    One little problem, I don't have a battery charger. (Before I continue, please don't just tell me to buy a charger, I'm broke and want to try this anyway :)

    Doing a little research, this is the plan I have come up with for a power supply:

    Convert the standard wall outlet AC to DC using a bridge rectifier. I have four three-amp, 300V silicon diodes to make it with.
    I also considered using a single diode to cause a sort of half-wave rectification, creating a pulsing effect to aid in rust removal; does this idea have any merit?
    Now, I don't know what kind of current I want for this project. Should I try to salvage a transformer to lower the voltage going in to the rectifier?
    I also heard that I could put a simple light bulb in the circuit, in between the diode(s) and one of the wall outlet plugs. This would supposedly act as a current limiter.

    How does this plan sound?
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    At the moment your plan sounds very dangerous.

    You need to use a transformer to reduce the mains voltage down to something safe.

    Then you rectify it.

    You will have to employ a circuit to limit current to a safe value (may be as simple as a resistor), or use a transformer that is designed to limit the current.

    Yes, placing a lamp in series with the mains side of the transformer will very effectively limit the current. It also has the advantage that it won't overheat, and that you can simply change bulbs to change the current.

    I make no guarantee that this will work to de-rust anything.
  3. Militoy


    Aug 24, 2010
    Definitely use a transformer to lower the voltage, and isolate your project from the mains. I have used the bulb trick in the past to limit current - but I used a 120V bulb in series in the low-voltage side of the circuit. It worked just fine. This kind of system has been used successfully for many years by antique engine restorers to strip rust off of old iron parts.
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