Instructables
Picture of Power your breadboard with USB
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I am writing this Instructable because I´ve got a lot of questions about my little USB-powersupply for my breadboard and a lot of request to write an instructable about it. I needed a new one anyway because my old one died because of a cat with sharp teeth.

I think that it is safe to say that most of the people who make (big or small) electronics-projects have a pc or laptop in theire hobbycorner and a lot of projects need 5V for IC's or microcontrollers. So using power from a USB cable isn't that farfetched and lets face it: a lot of devices around us use a USB-connection to get their power or to charge their batteries.
 
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Step 1: About USB-connectors and -power

Picture of About USB-connectors and -power

For this Instructable you can use any USB-connector you like (or you can even cut the cable and solder the wires) but I will use a B-type. The pins always have the same function for all types of connectors.

 

Pin# Color Cable Function
1 Red Vcc (5V)
2 White Data-
3 Green Data+
4 Black Ground

Voltage = 5V
max Current = 500mA

 


Step 2: What do you need?

Picture of What do you need?
In this Instructable we will make a very simple power supply with only the USB-connector and a power-on led. But you can add whatever you fancy such as a power on/off switch or or a regulator to get 3,3V (fused or not) or........

So for this Instructable we need:
  • USB B connector
  • Some headerpins
  • An LED
  • A 150Ohm resistor
  • Something to hold the lot together
  • soldering iron and solder
Please be careful when soldering. Children should always work under adult supervision!


Step 3: Leds get our hands dirty

Picture of Leds get our hands dirty
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Soldering everything together is actually very easy.

  • Connect the led with pin1 (Vcc) of the USB-connector and then connect it to pin4 (ground)  with the resistor inbetween.
  • Connect pin 1 with one pin of the headerpins and pin 4 with the other.
  • I soldered another pair of pins to the board but they are not connected. They just give some extra stability when connected to the breadboard.

     

haiwuxing1 year ago
Good! Thank you, this is what I need.
Kante Tech3 years ago
Nice this was very easy to make instead of the other complex ones. I feel like this would work for people who are kinda of in a rush and is looking for good quality.
Now if i was to add a 8 pin push switch it would be between the resistor and the Led right?
janw (author)  Kante Tech3 years ago
It should be between pin 1 of the USB connector and where the LED is
MarkTBSc4 years ago
Unfortunately with this design you don't have access to 500mA. You only have 100mA maximum. The USB specification will supply 100mA to anything on the bus, but it's designed to only supply its maximum 500mA once the hardware in the device has introduced itself and sent a higher power request. Without using a USB controller/interface chip in the power supply circuit you're limited to 100mA.

There are rumours of Apple building high-power USB ports into their newest computers that will supply between 1 and 2 amps. That's so you can speed-charge an iPhone4 or an iPad without using a mains charger.
Just an idea, could you not run your breadboard from 4 X 1.2 volt nicads, and then charge the nicads via a schottky diode? i quickly hooked up such an arrangement, and measured between 13 an 19ma charge.

This would give you the instant current when demanded and still be trickle charging at the same time.

Saying that, i have a 4 X AA cell nicad charger, and looking inside that, all 4 cells are connected directly to the 5v USB bus!
janw (author)  MarkTBSc4 years ago
You are 100% right. I forgot toput it tat way in the instructable indeed.

I made this quickly to do some testing while using the 5V from my laptop. I did not need more than 100mA and it still works fine for most of the smaller projects I do. For all the rest of the testing I use a regular power supply.

I'm using a resettable fuse in mine. here it is: http://www.sparkfun.com/commerce/product_info.php?products_id=8357
janw (author)  djshortstuff4 years ago
good idea indeed
BjornR4 years ago
Perhaps you should've added a current limiter. There are always people (yes i'm referring to me) who try to get x Ampéres out of a breadboard power supply.
Even the best make short circuits.

This instructable however was very interesting, it does come in handy !
janw (author)  BjornR4 years ago
There is a currentlimiter. If blue smoke comes out of you pc then the current will be limited to 0 Amps ;)

but I guess you are right.
 i did something like this but with the usb cable 
thgame4 years ago
Cool :)