Portable 5V Regulator

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Introduction: Portable 5V Regulator

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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.

3 People Made This Project!

  • I've been trying to ...-day26

    day26 made it!

  • Nice little power so...-kohellus

    kohellus made it!

  • I did one, no quite ...-lapenta

    lapenta made it!

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41 Comments

I've been looking to build a very similar circuit, but didn't realise it could be made so small!

Is there any chance you could post a diagram of the circuit board, as it's hard to tell exactly how you've built it!

what is the max amps this can do

I was wondering how long one 9v battery powered your arduino on this setup. I am looking to do something very similar.

can you explain to me, why you used the capacitors. In my circuit analysis programm they don't make a difference. I still get 5V

The capacitors are typically not needed if the input voltage is relatively stable (like from a battery), and if the load is not a greatly varying load. However, as a typical design practice, they are added to help smooth out the input and output voltages. For most of my projects, I don't use the capacitors, unless I truly see some issue with my circuit not working correctly. Since this project shows very short leads, there would not likely be any interference caused by outside electromagnetic fields. If the input or output wires are very long, then there is more chance they could be affected by nearby electrical or even changing magnetic fields (like a motor or other wires with higher current), they could act like antenna and pick up noise which would affect your output voltage.

Capacitors don't like to change their voltage very quickly, so if used, they will help reduce or eliminate any unwanted changes from these outside influences. The frequency and amount of voltage ripple reduction is determined by the values (Farads) of the capacitors, and depending on the resistance, you can calculate the RC time constant to understand how smooth the ripples can become. They also help to reduce any unwanted voltage spikes that may occur, depending on how complex the circuit actually is.

Hope that helps.

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.

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.

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?

Can that diode be replaced with anything? I have everything BUT 4001