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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.

 About USB-connectors and power

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For this tutorial 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

What do you need?

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In this tutorial 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

Lets 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.