## Introduction: 5V Breadboard Mini PSU

Micro PSU to power a breadboard with 5 volts.
Connect to 9V battery, 12V or any other DC powersource from 8 to 18 volts.

## Step 1: Components

To build this you need:

• Some electronics skills. Soldering, knowing how to follow a circuit diagram etc..
• 1 voltage regulator LM 7805
• 1 10uF capacitor
• 1 1000uF capacitor (you can use any big electrolyt capacitor here, doesn't have to be exactly 1000uF)
• 1 100nF capacitor
• 1 LED for power on indication
• 1 resistor to to take the voltage down from 5V to whatever your LED runs at
• 1 screw terminal for the input voltage
• 1 switch for input voltage on/off
• 1 perfboard, the type with copper eyes, not stripes
• 1 2-pin connector to plug the unit into the breadboard

Resistor calculation

R = ohm of resistor
V = voltage for the LED (You can find this in the datasheet for your LED)
I = current for the LED (can also be found in the datasheet)

R = (5-V) / I
Then round up to the nearest resistor value you can find.

## Step 2: Minimize

Place all the components on a perfboard to see how tiny you can make it.
I won't give any detailed instructions here, as the size and layout of the parts you use may vary from mine.

Put the components in as tight as you can, while verifying that you can in fact complete the circuit on the underside of the board without adding any wires.

When you've found your minimum size, cut out the piece you need.

## Step 3: Solder

when you have figured out a way to squeeze your components together, it's time to solder.

Check the pictures to see how I did it.

## Step 4: Enjoy

Anyone know what the ceramic cap is for? I don't have 100 pF so can I use a 500pF or 1000pF cap? Thanks

The 100 pF capacitor reduces noise. It will work without the capacitors. But to be on the safe side, and provide a stable power source, we add capacitors. The 500pF will work just fine :)

will the 1uF work?

Hi, it that a 100pF capacitor or a 100nF capacitor? In the photo you show 100nF.
Thanks!

oh sorry I didn't see it at first.

I know how all this works but can you post a schematic? I have a large breadboard and I can just plug all the stuff in a little corner somewhere

how did you solder like that? whenever i do it, the solder all clumps together onto one pad.

Usually when you bridge solder two joints, you ball up both pins, then get a little solder on the iron and start applying between the points. If there is enough solder on the iron or the 2 pins or all 3, then the bridge will automatically join together. But do it quickly because you do not want to burn the electronics. If it does not work the first time, add a little more solder until they join.

ok, well i figured it out anyway. thanks. i like this way of soldering, even though it uses a lot of solder.

Why don't u use staples?

try using flux in addition to the flux your solder might bear in soldering... works wonders...

i have to take soldering lessons from u seriously my soldering sucks so much. i burn half of my projects.

Why don't u use staples?

Tip: Dont use an arc welder.     :D

you are most likely not using the right watt for the project you are own... sometimes it is better to use higher watt irons because they allow you to work more quickly... although your project's sensitivity will depend on the proximity to heat sensitive circuits... a good soldering station might be worth the investment so that you can play with many wattages and figure out which one is correct for the type of work you will be doing...

is it safe to skip 100nF capacitor?

Mine has a modular power connector.

Hi,

Thanks for this clean, clear and small tutorial !
Although something is unclear to me, about the resistance for the led. (the most simple part of your tutorial) I understand it's depending on the Vin voltage, it's Ohm's law...

but:

How can I choose the resistance value, if the input voltage is not fixed?

As you say input from 9V to 18V, (I guess that's the 7805 spec.)

Is there another electronic trickery I can use to prevent my led to blow up at 18V, and still be lit at around 9V ?!
(I feel stupid asking this, I lack general electronic knowledge, sorry for that)

Cheers!

Xained, hes putting the led on the output so its always powered from 5V regardless of the input. Note that he placed the LED in backwards in his schematic too. Also, an LED can light up even with very large resistors and low currents. Whether you use a 220 ohm or 20kOhm it will still light up, albeit much dimmer with the 20k resistor. The key is just dont go over 20mA current through the LED.
~Gabriel
www.ElectricRCAircraftGuy.com

Cool!

I made a layout for it. :)

Here's another pic.

Just a note to let you know I have added this ( a year ago ) to the instructable:

Comprehensive Guide to Electronic Breadboards: A Meta Instructable

Take a look at a bunch of project involving breadboards.

good project,i need 12v dc 1000amp

I think you mean 1000milliamp 1000 amps is 100 times what most household outlets put out

so outlets are like 10 amps?

yea most household outlets are 10 amps but there are some that are occasionally 15 amps

my shed had 3 20 amp 3 prong outlets and one 100 amp outlet for an AC arc welder

ok i havent seen a 20 amp outlet personally but that doesnt mean they dont exist and the 100 amp outlet is proabaly 3 phase

not really. All outlets in your kitchen and your bathroom are 20amp look in your panel. Also there is no such thing as a 3 phase service for a residential house. His 100 amp outlet for a welder is very normal. And all the rest of the outlets in your house are all 15amp. Have any of you reset a breaker in the garage when the lights go out. Electrition for 8 years.

you are generalizing a bit too much i think. I have no 20 Amp outlets anywhere. 16 is my max

15amp outlets are very common in newer housing (most of mine at home are) a 20Amp circuit in residential is pretty rare unless its for a specific appliance like a microwave or something or in a workshop.

interesting...

actually 66.66666666666666666666666666666666666666666666666666666666666666666666666666666666 times

lol you trying to liquefy flesh?

Nice build,going to have a go at making this since have all the required parts,the nice and clear schematics and pictures will speed up my build also.

why do you use a 1000uF and 10uF CAPACITORS. instead from the data sheet of the LM 7508 it is 0.33uf and 0.1uF. can you please explain that to me.Also how do you come about using those values. is there any calculation behind it? thanks in advance.

What are all of the capacitors for,and would it work without them?

I beleive the large cap is just to smooth out the power output so you dont get droops as badly. The other small ones I think are important though but I cant see the schematic from this post page so I can't confirm :)

soo...would this work to use a 12v wall wart with this to power the 8*8*8 led cube

As long as you dont exceed the operational voltage and amperage of the 7805 you could use just about anything as a source. Just keep in mind the greater the difference between source voltage and the 5v out the more heat you must dissipate off the 7805. For 12V source you will probably want a small heatsink on it.

how do you cut the circuit board? mine keeps cracking and like, messing up!

For the perfboards I generally use the scoring method. Score a line across where you want to cut it with some sort of blade then snap it quickly. Usually works :) if its a big piece I use a fine-toothed saw or dremel.

dremel with straight edge adapter... or a jigsaw works great but can leave crazy lines if you are doing it freehand... some people drill a line of holes close to each other and then snap it like a sheer line... a vise works great for this method...

you could try using cable cutters

i use a coping saw. but i dont use that type of board. i get fiberclass strip board and use a circuit breaker to cut the tracks that are need to make a pcb type of thing. you get the boards at www.maplin.co.uk

Thanks!

ive got a question being an electrical noob. What is gained by the parallel caps? I understand having a single cap to "even out" the flow vaiations on the 5v side, but how are the calculations done for what sizes to use? How does having the particular variety that you are showing: 1000uF then 10uF then 100uF? Thanks!

Switchless power supply, intended for the 8x8x8 LED Cube. The Cube already has a switch.... :)

Will this work to convert 12v auto to 5v usb?

yes it will, but i would reccommend putting a heatsink on the 7805 because it can get really hot from regulating that much voltage.