Portable 5V Regulator

Contest Winner
I made this 5V Portable Voltage regulator to be part of my Palm Arduino Kit.

I placed the circuit right on the 9V Battery holder with double sided foam tape.
The circuit was one side circuit.

I placed the components on the solder side of PCB board, because I wanted to use the component side of the PCB to stick to the foam tape and place it right on the top of the 9V battery holder.

The 5V Portable Voltage regulator consists of

Slide switch
1N4001 Diode
100uF Electrolytic capacitor
10uF Electrolytic capacitor
78L05 Voltage Regulator with TO-92 package
and 2-pin Female socket with hookup wire
PCB about 5/8" wide x 1" long.

The schematic of this 5V Voltage regulator is from my notebook when I started to learn embedded electronics.  As when I first learned why the diode was added. Because it blocks current from flowing in the opposite direction. And it will block current from flowing backward and damaging the system if you accidentally hook up the power supply the wrong direction.

To built this Portable 5V Regulator is quite easy.
Just solder the components according to the schematics.
And be careful about the polarity of the the diode, and capacitors.
For the 78L05 IC also need to be careful on the pins connectivity.

I used 2-pin female socket as the power connector.

NOTE: Thanks to bamfieldjames for an excellent question regarding the LED indicator. So I revised the schematic (as shown), by adding a LED indicator. The dotted connection near 5V output is an option if it is not feasible make a connection at the switch.

Thank you so much for this instructable. I went to my local electronic hardware store, picked up the components, even got a simple multimeter for 8€ and soldered everything together. My measurement was 5.00V, it worked great.

Thank you so much for your circuit diagram, never saw something so simple and well explaining. I just connected everything the way you drawed.

I will use this to power my Arduino Nano with a 9V battery.

Thanks for sharing.

sath02 (author)  WalterBeiteryesterday

Thanks for the kind words!

It would be nice, if you could click the "I made it!" button! :)

And please check you PM mail box.

Jolonar1 year ago
So I made this cool little device, and it charges my phone just fine. I used the same parts as described in the parts list, however, when I test it with my hobby multimeter from Radio Shack, it reads 4.95 volts. As I'm using this primarily to power up my usb stick for an usb otg (0n the go) cable for my phone, I think it needs approx. just over 5v to power up the usb. That I'm uncertain of. Any advice?
maxxion1 year ago
Can that diode be replaced with anything? I have everything BUT 4001
sath02 (author)  maxxion1 year ago
Yes, you can use 4004 or 4007.
The PIV voltage for a 1N4007 is 1000V, and 50V for a 1N4001.
maxxion1 year ago
(removed by author or community request)
Whoops, was going to re-type this one along along with the other message above as one comment, but you replied to it pretty quick :P
sath02 (author)  maxxion1 year ago
That should be OK.
Looking forward to see the result on instructables.

maxxion1 year ago
Had just a couple questions about this. I'm trying to build up a DS charger (I, in a sense, inherited my late fiance's when we were young minus a charger), and it said I needed a 5v voltage regulator. Yours looks super easy and fun to build, so my questions are thus:
Is the switch just for turning the power on/off, or does it have some less obvious purpose?
Could the 9v battery be replaced with something like an old phone charge to step (I belive they are around 12v) down?
sath02 (author)  maxxion1 year ago
Hi maxxion,

>>Is the switch just for turning the power on/off, or does it have some less obvious purpose?
Yes, it's On/Off switch.

On the second question.
>> Could the 9v battery be replaced with something like an old phone charge to step (I belive they are around 12v) down?

Frankly, I never use this Regulator connects to the Power more that 9V battery.
Since it was designed specifically for 9V battery.

Anyhow here is a data sheet for the regulator IC (LM780L5)
It said the max. voltage input is up to 30V. With the current output of 100mA.
You can try it (AT YOUR OWN RISK!)

If I were you I would look into something like this
5V 1A (1000mA) USB port power supply. (
It has USB port with it. And find USB to DS (power port) converter cable.
Or if you could modify the USB cable to suit the DS power port yourself too.

Hope this help!
sath02 (author) 1 year ago
Thanks to all the voters!
I do really appreaciated!!
sath02 (author) 1 year ago
The award has arrived.
Here's what I got!

ynze1 year ago
Pretty drawings of the schematics! Nice and very useful project, thanks!
sath02 (author)  ynze1 year ago
vricsi941 year ago
On the label of my charger it says its maximum output is 700mA. But this regulator's max output is only 100mA. Is this going to be a problem? What could I do to increase the max output?
sath02 (author)  vricsi941 year ago
You charger get the power from the AC line?
This regulated power supply is from 9V DC battery power!
I use this regulator with my palm-sized arduino to do some small experimentatio project while I'm traveling.
And I tried this with my XBee project, with no prblem.
But when I am working on the project, for example, use arduino to control motors, etc. I will provide separate power to the motors.

For the question:
What could I do to increase the max output?
This is a question that I would like to know also. Are there any taker?
Thanks for your quick reply! Yes, it gets the power from the AC line. And yeah, I know there's only a 9V battery, I was just wondering if it could be done. Oh, and I forgot to mention that I wanted to charge my phone with it, sorry for that. I'll keep on searching for a solution, and if I find something, I will post it here.
sath02 (author)  vricsi941 year ago
Something like this
Might work well for you, better than 9V., it used only two 1.5V battery.
I use it to power my Arduino too.
Take a look.
Thank you so much! I think this one will be perfect for me:D
I'll start gathering the components for it:D
DoctorWoo1 year ago
I just finished making one of these, and I have a problem: mine appears tio be putting out 7.44v, not 5. I've gone over my circuit about six times now, and verified all the leads are going where they need to go, but I'm still getting that 7v. The LED and switch do work, however.
sath02 (author)  DoctorWoo1 year ago
What kind of Voltage Regulator you're using?
Could you provide a link to your Voltage Regulator?
Or could you post a picture of your circuit?
The regulator I'm using happens to be a 78L05. I can;t locate the link to the actually regulator, and I'm unsure if it has the TO-92 pack to it. I'm sure it does, as I did search for the 78L05 with a To-92 package.

Here are the pics for the board I have
sath02 (author)  DoctorWoo1 year ago
Thanks for the pictures.
It helps a lot.
I doubted that there are two spots that doesn't seem right to me from the pictures.

First, under the regulator, left and right pins of the 78L05 seem to be connected! It's not supposed to.

Second, the position of the switch.

Look at the comments in the attached photo.

Hope this help!
Well, I feel silly now. That connection at the regulator was what did it. I'm getting 4.97 now.

Thanks for point that out!
sath02 (author)  DoctorWoo1 year ago
I did that before too! So, your are not the only one.

Glad the problem solved! :)

DoctorWoo1 year ago
I'm looking to make one of these for a portable breadboard PSU, and was there anyway to hook up an LED as an indicator light? I know there is a way, however...I'm not too grand with eletronics of this nature, and needed a bit of a poke in the right direction. Any help would be grand!
sath02 (author)  DoctorWoo1 year ago
Thank you very much for an excellent question regarding an indicator LED.
See the second schematic above for the placement of the indicator LED.
Revanchist1 year ago
Could you regulate it to be more precise? maybe 5.00 Volts stable? If so does anyone know how I could achieve this? I'm looking to build one of these but I need a stable 5.00 Volt supply.

sath02 (author)  Revanchist1 year ago
Hi Ravanchist,
Technically, I don't know how to achieve more precise 5V. I am just an artist!
And the circuit I used came from what I learned from the expert, and I recorded on my notebook sometime ago.
But I found this (project) website providing great detail regarding the power supply,

and might be useful to you.

Hey! Thanks a lot this is gold! but what I meant more was something like what Apple has in their chargers... if you check with a voltmeter the voltage generated by an Apple charger vs the rest of the world (just kidding) you'll see that Apple's is one of the most accurate and stable...

Anyway thanks a lot and great job on the 'ible!
sath02 (author)  Revanchist1 year ago
I'm glad that help! And thanks for kind words.
This is simple yet brilliant, I've got tons of those 9V Battery holders laying around and this has given me something to use them for...

One possible criticism I could suggest, is to prevent shorting out (for one reason or another) is cover the PCB (Minus mechanical moving parts... e.g; the switch) in Hot glue?

When I give it ago myself I'll be covering it in hot glue to make sure it's secure and non-conductive lol
sath02 (author)  Dominion-Network1 year ago
Hot glue tip is great! I'll keep that in mind.
mh76dk1 year ago
Nice and tiny, my only complaint (if you can call it that - ill pretend its constructive criticism :) is that it could use a housing of sorts around the pcb (or possibly around the battery/pcb as a whole)
mh76dk mh76dk1 year ago
I just saw the previous related instructable and noticed it needs to fit inside the box, that might invalidate my suggestion for this project (or at least complicate it a bit, due to size-constraints)

sath02 (author)  mh76dk1 year ago
Thanks for the comments.

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