# Where can I have custom made a variable dc switching power supply?

1. ### Xtensity

104
What sort of company would I contact to have something like this made?

I am looking to have made a Variable DC power supply capable of outputting up to 300-400 amps and up to 30v(and as little as well below 1 into the decimal region). Preferably as small as possible. My only requirements for it are to have both ampherage and voltage adjustable by their own course and fine adjustment knobs, as well as digital screens displaying the current Voltage, Current, as well as the current resistance of the circuit. Output holes for anode, cathode, ground, etc. I need the device being capable of running without deterioration for up to 15-20 hours aday everyday.

I don't mean to advertise this here, but does anybody know where I can have something like this made? Money is not an object. Willing to pay $,$+. I was unable to find any freelance people in the area and I'm not sure what sort of company can do things like this. The idea seems plausible enough I just don't have enough EE knowledge on my own to build one reliably.

723
Where are you located? -- I work in this field, I do not build these but can direct you to potential suppliers.

I do not know what you mean by output holes for anode, cathode Ground..?

1dB? IN V that is like 12%, in power we do not use dB much - is this what you need? ( that is pretty low regulation)

Last edited: Dec 12, 2013

### Staff: Mentor

That's a pretty big power supply! You realize that it is more power than you can draw from a normal electrical circuit (in a home or small business)? You will need a specialized high-power AC Mains Breaker Panel installed to handle that level of power. Is your source AC Mains voltage 120Vrms or 240Vrms?

Here are some commercial power supplies that come close to doing what you want:

http://www.telonic.co.uk/products/categories/dcps/delta_sm-series.asp

Do any of them look like they could work? You could use Google to try to find similar power supply manufacturers to see if you can find an off-the-shelf power supply that will work for you.

Beyond that, I do have a very good power supply design consultant from here in Silicon Valley (California, USA) that we use at my company. I can PM you his contact info if you want. He normally works on more normal-size power supplies, though, but it might still be worth it for you to contact him to ask his advice.

4. ### Xtensity

104
I'm not an electrical engineer so I am not complete on point with the right terminology. Honestly the power supply might do fine with max 5-6 volts, probably even less. I think most of the time the system will need around 1-2 volts.

I've looked at welder power supplies that have far exceeded my requirements, and I know those can be plugged into a regular home outlet, the only issue with those is that I will not have a constant reading or control over the voltage/current.

Like I said I'm not an electrical engineer(yet :p). I just know I need to be able to direct as low as 100ma up to 400 amps of current through a circuit by connecting the anode and cathode wires from the power supply to the circuit. I hope this makes sense?

Part of the goal of my projects are to for instance send 1 - 15 Faradays through the circuit over the course of an hour, except run this for longer periods. So for instance, if hypothetically running at max 400a(which I'll probably never go that high), I would target to pass 225 Faraday's through the circuit over a 15 hour period.

The reason I need to control both voltage and current is because the current requirement will differ depending on the system/circuit set up, and the voltage will have to be varried because the system has a constantly changing resistance. This means I will need to maintain the wattage of the system and keep the current constant(by changing the voltage)

I hope this explains things better. I have no idea how the big these things scale up in terms of their voltage capacity and what not.

I found this online for instance:
http://www.newegg.com/Product/Produ...M2382&ef_id=UqpFRAAAAAUqeHYG:20131212232244:s

The set up looks perfect for what I need but it doesn't come anywhere close to meeting my current output requirement, and I won't really need a voltage output that high.

### Staff: Mentor

Farads are a unit of capacitance, so you do not "send" Farads through anything. You send current in Amps for some period of time like Amp * Hours, which is a measure of energy.

With a power supply, you will typically set the output voltage, and set a current limit. The actual current is determined by the load resistance (unless that would be above the current limit, in which case the output voltage drops to limit the output current).

The outputs of a power supply are typically just called Vout and Ground, or + and -. The terms anode & cathode do not apply to a power supply.

6. ### Xtensity

104
Thank you. When I speak of Faradays I speak in terms of the system I am sending the electricity through. The circuit will meet a certain [goal] requirement for instance only after 8 Faraday's, aka, 96,485 * 8 = 771,880 Coulombs have traveled through it. These are hypothetical numbers of course. A 20A power supply as linked above could only supply .75 faradays per hour [maxed out] when I am needing at least 7-8 Faradays per hour. For these particular circuits that I am sending the coulombs through to work properly the current must be maintained perfectly[give or take a few mA], in spite of the changing resistance.

The reasoning I was attempting for changing the voltage would be even though the resistance changes, the load from the system will not. So if the resistance increases, and the voltage stays the same, the only way to satisfy the power requirement would be to vary the voltage. I hope this makes sense. I just got something to eat and feel I was able to explain this better than previously.

The power supply I would just need to display the system voltage, current, and resistance, while giving the ability to set the current and voltage(like in the link above) and I can do the calculations myself. I am not really looking for a super fancy one that autocalculates and autoadjusts the voltage, just one that can set the voltage and amperage of the system and be able to meet the requirements I have.

8. ### Xtensity

104
Oh Thank you! I had completely missed that link! I will look into these devices.

I see the supply voltage on these is in AC. Will there be an issue plugging them into a normal wall outlet?

### Staff: Mentor

At the power levels you mentioned before, you will need to have a custom 100A panel (or higher) installed by a licensed electrician (and inspected by your local city officials).

10. ### the_emi_guy

593
You must be trying to electroplate something enormous! This would be about 1Kg of deposited metal per hour right?

723
12. ### Xtensity

104
Even at 2400 maximum watts? (6v * 400a)

I looked up some videos of these devices and it does seem that while they do have knobs for both voltage and current, setting the current to one thing will auto-adjust the voltage to maintain the current depending on the resistance of the system.

723
This is simply current control mode, a common feature. I was trying to clarify that you can not control both at the same time. The fact it has a knob to adjust the current does not mean much unless you can understand the product specification. Is it a limit or a set point? And does that setpoint have feedback "closed loop control".

You mention that is needs to respond to the load, well how fast. How much current ripple can can you accept. Do you need line isolation ( galvanic isolation), how is it grounded. Does it need to be UL - or other certification. As was pointed out earlier - this does look like a plating rectifier - have you looked into those?

Your spec is moving around - I suggest looking for a DC power supply that is a) Close enough, or b) close and you identify the features you need that it does not have - then ask the Mfr for a customization or approach a builder to make this.

To specify a custom system from scratch requires a lot of info that you do not seem to have yet, there are about 6 common ways to build something like this depending on ALL of the requirements. You will need to fully define the power supply - or describe the application and let someone determine the power supply needed.

I am assuming you only need one of these? ( http://en.wikipedia.org/wiki/Project_management_triangle )

14. ### Xtensity

104
I contacted a sales rep from the company that berkeman linked and they have pointed me in the right direction and explained what I would need to accomplish my goals. Thank you to everyone for the replies here!