# CC/CV Power Supply

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#### royce

##### New Member
Hi, all!
New to the firum and happy to have found it!

I am a hobby machinist and I am starting to add ALuminum Annodizing to my home hobby shop. The method I will be using requires a controlled current power supply for best results, but they are fairly expensive. ($3-400) My requirements (ideally) are a 0-15V, 0-3A CC unit. Most units like this also seem to have Variable/controlled Voltage, but that is not a necesity for this dedicated power supply. I need to maintain a controled current density and let the power supply vary the voltage as the annodic material varies its resistance [as coating is deposited]. Whe the resitance peaks and the voltage starts downward....voila! She is done! For this part, a meter would be nice. I guess an built-in curent meter would be nice, too. ALthough both could be digital to keep costs down. I can construct almost anything so if anyone has a schematic for such a power supply I woud greatly appreciate a look at it. #### Johnson777717 ##### New Member hmm...controlled current. Well, here is a link to a site with a bunch of power supply circuits. I'm not sure if any are what you need, but the circuits may come in handy. Good luck! https://www.commlinx.com.au/schematics.htm #### k7elp60 ##### Active Member Constant current power supply I suggest using an LM338, as it is a 5 amp regulator. It can be configured as a constant current source that is adjustable in current. I don't think it will go down to 0 current however. If you can give me a figure for minimum current I see I can provide you a schematic with parts list. I suggest that you consider a fixed supply about 20 volts and let the current regulator provide the adjustable current, thus the load voltage will be the 20 volts minus what is dropped across the regulator. #### Optikon ##### New Member royce said: Hi, all! New to the firum and happy to have found it! I am a hobby machinist and I am starting to add ALuminum Annodizing to my home hobby shop. The method I will be using requires a controlled current power supply for best results, but they are fairly expensive. ($3-400)
My requirements (ideally) are a 0-15V, 0-3A CC unit. Most units like this also seem to have Variable/controlled Voltage, but that is not a necesity for this dedicated power supply. I need to maintain a controled current density and let the power supply vary the voltage as the annodic material varies its resistance [as coating is deposited].
Whe the resitance peaks and the voltage starts downward....voila! She is done! For this part, a meter would be nice. I guess an built-in curent meter would be nice, too. ALthough both could be digital to keep costs down.

I can construct almost anything so if anyone has a schematic for such a power supply I woud greatly appreciate a look at it.

Good luck

#### royce

##### New Member
Excellent, and thank you again!

I will go with a regulated 20VDC power supply just to keep things under better control. Is a 5 Amp transforer enough or should I go higher than the 338 is designed to handle, say 7 or 8 AC 5 Amp rating
Full wave Bridge Rectifier
I'll need a votage regulator to produce 20 VDC
I shouldn't need current limiting as the Constant Current control will govern the current draw...Correct?

#### k7elp60

##### Active Member
CV/CC power supply

Royce,
I didn't address the 20 volt power supply, as there are a lot of variables that I do not know. One is the duty cycle. In other words if for example you are supplying lets say 3 amps to the tank, how long will the 3 amps
need to be supplied, and what percentage of ripple will the tank stand?
For linear power supplies like you described, a transformer, a bridge rectifier, a filter and a regulator you may want to read a previous post that I made on 12/28/03 in the general electronics chat. Here is the url"
It would be possible to use a LM338 as a voltage regulator also.
Course what you read on that post is my opinion and the results of a some

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#### royce

##### New Member
Duty Cycle: @3Amps, which will probably be the highest current that will be used in this set-up (current is calculated by the surface area of the work piece) the system might run for as long as 90 minutes.

As for PSU specs...let's just say that I would like it as good as is practical for a beginner like me to build (with high hopes & ambitions!). I don't have the knowledge to discuss ripple & long term stability. I do know that I have seen specs based on a 15V 0-1 Amp system from others doing this setup and they mentioned things like:
Current Regulation: +/- .01% from 0-1 Amp
Absolute Accuracy: +/- .5%from 0-1 Amp
Long Term Stability: Better than .1% over a 3 hr. period
This current control system was powered by an HP Printer 15V/800mA power cube. Only small test pieces were done with this system.

I hop this helps.

#### royce

##### New Member
I just read through the post you sent me to...very interesting. Funny how the values seem to closely match those of my experiment.

From what I gathered, I would want to use larger caps to have a lower ripple, or possibly more than one cap. Again, I suppose since I am building it, I might as well build the best that I can [within reason of cost & design].

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