Handy Power Supply

If you find my design interesting, you could make a small donation:
http://paypal.me/RegisHsu

This is a small size power supply with low cost and easy to make that only taking about 5 more hours. I was very happy with it and would share with you.

Power Supply Specifications

Input: 5v-16v/3A DC

Output: 1.3V - 15.5V/2 Amps

Step 1: Materials and Tools

Here is a list of materials and tools I used for this project.

MATERIALS:

2 x LM2596S DC-DC module link

2 x Voltage/Current DC0-100V LED meter link

2 x WXD3-13-2W-10K link

2 x D3-13-2W knob link

2 x 4MM banana jacks(Red + Black) link

2 x 4MM banana sockets(Red + Black) link

1 x switch 117S 8.5*13.5MM link

1 x Power Jack DC-022 DC 5.5mm 2.1mm link

1 x AMS1117-5V link

1 x 5V 30mm fan link

6 x 2.5mm/6mm screw

1 x DC adapter 16v / 3A, the voltage range between in 9v~16v would be better.

TOOLS：

3D printer with PLA withe & gray color

Soldering iron

Step 2: Make the Enclosure by 3D Printer

Download the STL file from here http://www.thingiverse.com/thing:1420193

And take about 2 hours to print them.

I have removed the USB slot which the 2 holes on the front panel, the new one will not be any hole on it.

Step 3: Modify the DC-DC Converter

take away the small one of potentiometer which is on the DC-DC module, and replace the big one of potentiometer which shown in the picture. The picture 1 is not correct, please follow the number 3-3, 2-2, 1-1 to connect together as picture 2.

Step 4: Schematic and Diagrams

Refer to the diagram to connect all of parts together

Step 5: Assembler

put all of parts into this enclosure, and use the tape to protect the boards and wires to prevent any short circuit.

Step 6: Testing

Plug in the 16V DC adapter , and switch on.

Tune the voltage and measure by multimeter to see the result.

That's all and have fun.

Step 7: Start Working

I use it with my Spider Robot control board to do some experiment about MQ-2/MQ-135 air sensors.

It works fine.

If you are interested more about my projects, here is my bolg http://regishsu.blogspot.tw/

Comments

[AroAro]

Warning !!!
I have very bad experience with these pots, and very high costs!
In the design, resistance wire is distributed on a 10 turns and a contact is constantly dragging across the wire. At some point the wire is interrupted and the potentiometer is defective.

That's just a very small problem. It is very expensive if the output is connected to a circuit that does not tolerate the full voltage!
The defective potentiometer causes the control is interrupted and the output is the full voltage.

The better solution: - Connect a normal potentiometer and just a second potentiometer (about 5 - 10% of the voltage regulator) in series.
You do not have to screw for a long time and still be able to adjust the tension very precisely.

[blubbblubb]

nice instructable, i would like to build it myself, but im not sure
if im able to reuse an old 12V 2A power supply i have laying around. It
is an unregulated power supply, does anyone know if the dc-dc module
works with unregulated power supplies as well as with regulated ones?

[UNSEPARABLE TECHSCIENTIFICS]

NICE PROJECT MY COLLEAGUE!!!!

[RegisHsu]

thanks.

[magkopian]

Nice idea on using those multi turn potentiometers, that is going to help with setting your output very precisely without the need of having two separate course and fine adjustment knobs. The end result also looks pretty good!

The only thing that I'm concerned about are those cheap switching regulators. I'm pretty sure their performance is not going to be that good and the ripple and noise are going to be quite high. Obviously, that's not your fault since you aren't the one who build them or designed them. Anyway, the thing is that this can lead to problems if you are trying to power sensitive circuit like amplifiers for example, so you need to be aware of that. By the way, I'd love to see some ripple and noise measurements if you can.

Since you are not powering the power supply from batteries it might be a better choose to use linear regulators instead. If you mostly work with low power electronics their efficiency is not going to be an issue.

[RegisHsu]

I am using this project just for arduino and ESP8266 modules study. It might not good enough, however it helps me the dual power source requirement.

It would be happy/appreciate that if someone who can modify or improve this project.

[magkopian]

I was thinking about a more custom solution using a linear regulator
instead of a switching regulator module. If you're mostly working with
low power electronics like microcontrollers for example, a dual channel
power supply with a 0V to 15V voltage range and 800mA maximum current on
each channel should be more than enough.

From a quick search and
I found a very nice one, the LT3042 from Linear Technology. It has
ultra low noise capabilities and a very high power supply rejection
ration. It has a voltage range from 0V to 15V, not many linear
regulators can go down to 0V. The popular LM317 for example can go only
down to 1.25V. It has a programmable Power Good function which is a nice
bonus. It has a maximum of 200mA output current but it is parallelable,
which means you can put 4 of them in parallel to achieve an output
current of 800mA. There is even an application example circuit on page
25 of the datasheet. Putting many regulators in parallel also decreases
the noise even further. And finally it has a dropout voltage of only
350mV.

And about powering the regulators, you can use a
15V-0V-15V mains transformer combined with two full wave bridge
rectifiers and two big 2200uF capacitors. This will give you two DC
voltages of about 20V which is more than enough to power each channel.
And in case you wonder how you get 20V from 15V it's very simple. The
15V are AC, so after the rectification you will get a DC voltage equals
to 15VAC * sqrt(2) - 0.7V - 0.7V = 19.81VDC. The two -0.7V are the
voltage drops from the diodes.

The only thing that might be a
problem to you it is that it's only available on an SMD package, so if
you are not familiar with SMD soldering that might be an issue. Also,
the chip is a little expensive, I found it for $2.73 on LT's website and
for a dual channel PSU you need 8 of them. But that was just an
example, there are thousands of linear regulators out there, I only
searched for a couple of minutes and found this. If you do some research
yourself I'm sure you can find many alternatives. Any linear regulator
is going to be better than a switching one for your particular
application, even an LM137 will do the job if you don't care about the
dropout voltage and the voltage range that only goes down to 1.25V.

[RegisHsu]

wow, you are expert on the power. I will study it, thanks so much for providing the valuable information.

[magkopian]

Just noticed I made a small mistake on my previous comment, I meant to write 15V-0V-0V-15V transformer not 15V-0V-15V. Sorry about that, I hope I didn't confused you. I've also drawn a quick schematic to help you understand the concept better.

A power supply based to two isolated rails is very flexible. You can use it to power two different circuits while keeping them completely isolated. Or, you can connect the two rails in series and get a positive and a negative voltage, this can be quite handy for powering op amps. Or, you can just connect them in series to get a larger maximum voltage.

[keyyman2]

If you stick with the single polarity mode, might be a good idea to keep the ground terminal post on the left of the two variable outputs. That way the user cannot assume that you can stack/chain these as per a split design (typical used for powering analog opamp circuits etc.)

Another important point, if your source supply has a earth ground, it may feed through to the output, in which case you have to be careful that what you connect doesn't somehow cause a short in case it also has an earth ground that somehow ends up getting connected to the positive terminal.

[magkopian]

If the two rails are electrically isolated like in the schematic I posted, you can chain them to achieve a reverse and a positive polarity, there is absolutely no issue with that. It's like stacking together two 9V batteries to get +9V and -9V. Basically, what you have is two separate power supplies in the form of one. You could even use two different transformers instead of a dual one if you wanted, it's exactly the same.

As for your second point, the best thing you could do is to connect the mains earth to the chassis and make it available via a separate fifth connector. That way the user can decide whether or not he wishes to mains earth reference his power supply output and where to connect the mains earth.

[keyyman2]

Absolutely, I do this myself...

[efahrenholz]

Unfortunately that won't work with this. This is a plastic chassis.

[magkopian]

Indeed, I wasn't talking though specifically about this particular project. It was more of a general discussion about how to design a good dual rail power supply. Of course you need a metal chassis because you want it to act as an EMI shield too.

[keyyman2]

No issues with your recommendation, I was actually commenting on the original design.

[surya raju]

Hmm,thats a good one!do u have any specific ideas to build the supply?right now i can definitely use a low noise low power supply

[magkopian]

As I said previously, if you want low noise the best solution is to go for a linear design, use a transformer to drop the high voltage to a usable level (e.g 12V), rectify it using a diode bridge, smooth it using a huge cap (its size is going to depend on your maximum current that you decided to design it for) and a linear regulator at the end. Regarding the regulator LT has a huge collection of them, one of my favorites is LT3080 as it has the ability to go down to 0V, but there are many options to choose from.

The disadvantaged of a linear design is obviously the lower efficiency compared to a switching one, since a linear regulator basically acts as a resistor, but for a lab power supply this should not be a problem. It's a piece of test equipment and efficiency is last thing that you care about.

If you want to build a dual rail PSU checkout the schematic I posted on my previous comments, that should be a good starting point. The only thing that is missing from it are the linear regulators and their passives, and that's because as I said there are tons of them to choose from.

[surya raju]

regarding the multi turn pots,yes they are a good idea but the problem with chinese ones is that they are not linear always but have few jumps during the rotation.
(not saying that they are not good,we studentys have to make dowith it,but the cheaper option is definately better than paying lots for tyhe ones fromBourn)

Regarding the Switch supplies,(harmonics and noise issues)the best example is HamRadio,one of my elmer mistakenly carried a converted ATX to a field day!lets just say he had more of a bad day than a field day :)

[Cekpi7]

I made similar thing to change my LM350 with 2.5A 16V transformer and when i wanted to draw 2A from it it changed voltage from 10-12v and it wasnt really stable

Now im back to LM350

[richms]

Problem I have had with those panel meters doing something similar in the past, is they put the shunt in the negative line, so your 2 ground terminals are now not quite at the same voltage, putting the 2 grounds together will end up with the current readings being inaccurate.