Microcontroller Beginner Kit -
Building a 5 Volt Power Supply
Most digital logic
circuits and processors need a 5 volt power supply.
To use these parts we need to build a regulated 5
volt source. Usually you start with an unregulated
power supply ranging from 9 volts to 24 volts DC (A
12 volt power supply is included with the
Beginner Kit and the
Microcontroller Beginner Kit.). To make a 5 volt
power supply, we use a LM7805 voltage regulator IC
(Integrated Circuit). The IC is shown below.
The LM7805 is simple to use. You
simply connect the positive lead of your unregulated
DC power supply (anything from 9VDC to 24VDC) to the
Input pin, connect the negative lead to the Common
pin and then when you turn on the power, you get a 5
volt supply from the Output pin. The breadboarded
circuit is shown below.
The 5 Volt output
is connected to the red power supply line of the
breadboard. The ground from the input is connected
to the blue ground line of the breadboard and a
jumper wire is used to connect ground from there to
the common (ground) pin of the 7805.
Sometimes the
input supply line may be noisy. To help smooth out
this noise and get a better 5 volt output, a
capacitor is usually added to the circuit, going
between the 5 volt output and ground (GND). We use a
220 uF capacitor.
You can order the
parts for this kit. It includes:
