аааааааа Simple 5V power supply for digital
circuits
Summary of
circuit features
Brief
description of operation: Gives out well regulated +5V output, output
аcurrent capability of 100 mA
Circuit
protection: Built-in overheating protection shuts
аdown output when regulator IC gets too hot
Circuit
complexity: Very simple and easy to build
Circuit
performance: Very stable +5V output voltage, reliable operation
Availability
of components: Easy to get, uses only very common basic
аcomponents
Design
testing: Based on datasheet example circuit, I have used this circuit
аsuccesfully as part of many electronics
projects
Applications:
Part of electronics devices, small laboratory power supply
Power
supply voltage: Unreglated DC 8-18V power supply
Power
supply current: Needed output current + 5 mA
Component
costs: Few dollars for the electronics components + the input
аtransformer cost
Circuit
description
This
circuit is a small +5V power supply, which is useful when experimenting
with
digital electronics. Small inexpensive wall tranformers with variable output
voltage are
available from any electronics shop and supermarket. Those transformers
are easily
available, but usually their voltage regulation is very poor, which makes then
not very usable
for digital circuit experimenter unless a better regulation can be
achieved in
some way. The following circuit is the answer to the problem.
This
circuit can give +5V output at about 150 mA current, but it can be increased
to 1 A when
good cooling is added to 7805 regulator chip. The circuit has over
overload
and therminal protection.
The
capacitors must have enough high voltage rating to safely handle the input
voltage
feed to circuit. The circuit is very easy to build for example into a piece of
veroboard.
1.
Unregulated voltage in
2. Ground
3.
Regulated voltage out
Component
list
7805
regulator IC
100 uF
electrolytic capacitor, at least 25V voltage rating
10 uF
electrolytic capacitor, at least 6V voltage rating
100 nF
ceramic or polyester capacitor
Modification
ideas
More output
current
If you need
more than 150 mA of output current, you can update the output current
up to 1A
doing the following modifications:
Change the
transformer from where you take the power to the circuit to a model
аwhich can give as much current as you need
from output
Put a
heatsink to the 7805 regulator (so big that it does not overheat because
аof the extra losses in the regulator)
Other
output voltages
If you need
other voltages than +5V, you can modify the circuit by replacing the
7805 chips
with another regulator with different output voltage from regulator 78xx
chip
family. The last numbers in the the chip code tells the output voltage. Remember
that the
input voltage muts be at least 3V greater than regulator output voltage ot
otherwise
the regulator does not work well.
