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GAN109
5v Regulated Power
Source
By Michael
Simpson
Having suffered the
slings and arrows of projects powered by poor power supply designs,
I thought I would throw together a quick little application on
building one to use in your breadboard and microcontroller projects.
I'm basing the design
on a 7805 and 78L05 voltage regulator chips. They are easy to use and
require a minimal amount of components to put together a nice power supply
for a project or two.
I own several commercial
power supplies ranging from $15 to several hundred dollars. But they
all suffer from one problem. They take up to much valuable workbench
space.
I found by building some
very small 5v regulated supplies I could use several wall warts (AC
adapters) located under or behind the workbench. All I had to do is run
the DC side of the AC adapter to my current project.
Before I designed the
PCB for this project I came up with a few requirements for the power
supply.
-
2.1 mm coax power
input jack
-
.1uf
bypass capacitor
-
Pre and post
regulator capacitors
-
Led for power
indication
-
On/Off Switch
-
Integrated Reset
Switch for microcontrollers
-
Multiple contact
points for breadboard buss
-
Header connections
for non breadboard use
-
Ability to switch an
auxiliary power source
-
Mounting holes for
enclosure mounting.
Lets take a look at the
schematic that meets all the above criteria.
Let me talk a bit
about the minimum configuration for the above schematic.
-
7805 Regulator chip
-
.1uf Capacitor
-
100uf capacitor.
The 100uf will work on
the input or output side of the regulator chip so that leaves you some
room for a heat sink if you place the 100uf in the C4 position.
If you're not going to
use the LED then you don't need R1.
If the switch is not
used you will need to bypass it with a couple of jumpers.
The Aux power
connector was really meant for all those bots that require multiple power sources.
I got sick of forgetting to disconnect the batteries from the motor controllers.
If you decide to build
this regulator you have three choices. You
can breadboard it. Or you can use my custom
PCB.
Its only 1.2" x 1.9" I priced it at just over what I paid to
have the board done so others can build this project at a very reasonable
price.
The Parts
Complete Regulator
Kit
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