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Aluminium anodising power supply

ceefna

Sep 23, 2009
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Hi, my first post and wish for some expert advice as my circuit knowledge is limited to say the least. I have been messing with hobby aluminium anodising for a while now and wish to progress from using a battery charger I have no control over to a power supply that I can pre set a current then I can work out how long to anodise the part for. Please have a look at the circuit I am going to use. I need an ouput of up to 15 amps so I want to know if it is possible to hook up 3 of these in parallel to get the req current, but the biggest problem is can I control all 3 with just one pot for current control and one pot for voltage control. I have already got the LM338's and LM117's so if anybody has a better circuit Idea using these regulators all info will be greatly appreciated. Just a quick note please try to be as basic as you can!!! as I said I can build from plan but thats about it. So to round up I need a 0-15A/ 0-30V DC. Thanks for your time.
 

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Resqueline

Jul 31, 2009
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Yes, you can do it by simply triplicating the first LM338 & its 0.24 ohm resistor, and keeping just one R2 (feeding all 3 ADJ), LM117, & R3.
For the second LM338 you can triplicate it by adding a 0.1 ohm resistor in series with each output, before parallelling them. The 3 extra resistors will ensure they share equal currents. You keep just one R1 & R2, but you might want to increase R1 somewhat - to 220 ohms maybe.
Triplicate the capacitors as well to ensure stability.
I guess you know to use a substantial capacitor on the input of this circuit, after the rectifier, and a substantial heatsink for all 6 regulators.
 
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