Download Electricity for Amateur Radio

Electricity for Amateur Radio
How Much Electricity is Moving
Electricity is like punches
How many electrons are moving?
How many punches are thrown?
The number of electrons flowing is the current – more current more
Punches (T3A-03)
We have given you
“Ample” warning
Current is measured in “Amperes”
(T5A-01)
How Hard do You Punch?
We call it “Electromotive Force”
We Measure Electromotive Force in
Volts
(T5A-11)
When electricity punches hard
It will give you quite a “Volt”
Power
(Number of Punches X Force of the Punch)
More Punches – More Force
More Power
What term describes the rate at which electrical
Energy is used?
Power
(T5A-10)
We measure electric power in Watts
because
Lots of punches and lots of force
And you too will wonder
“Watt hit Me?”
(T5A-2)
Lets See If You Were Sleeping
(I’ve given you ample warning)
(This will give you a jolt)
Yup
(T5A-03)
(T5A-11)
(T5A-05)
One More
That’s Right
Electrical Power Leaves You Wondering “WATT” Hit Me.
The Power Pie
Power
(Watts)
If you have two pieces of the pie
You can always get the rest.
If you have two little pieces Multiply them
Together to get the big piece
Power = Voltage X Current
(T5C-08)
Voltage
Current
(Amperes)
What If I Have the Big Piece and a
Little Piece?
You divide the big piece by the little
Piece to get the other little piece.
Current = Power / Voltage
(T5C-11)
Now You Try It
(T5C-10)
Which part of the pie do we have?
Checking the Answer
Voltage X Current = Power
12
X 2.5
= 30
Another Try
(T5C-09)
What do we have?
13.8 X 10 = 138
Another Factor In Electricity Flow
How Much Resistance is Holding Current Back
Resistance Has Units of Ohms
“Ohm” My
How do I explain
Resistance?
Introducing the Ohm’s Law Pie
Voltage
Current
Resistance
Did Somebody Say Lawyer?
As before – if you have two pieces of the pie you can get the third
If I Have the Two Little Pieces I
Multiply to Get the Big Piece
(T5D-02)
If I Have a Big Piece and a Little
Piece I divide the Big Piece by the
Little
(T5D-01)
Lets Try You On It
(T5D-03)
Answer
We Can Do It With Numbers
90 / 3 = 30 Ohms
Your Turn
Answer
12 / 1.5 = 8 Ohms
And Another
120 / 80 = 1.5 amperes
Your Turn
Answer
200 / 100 = 2 amperes
Try It With Two Little Pieces
We multiply two little pieces to get the big piece
2 X 0.5 = 1 Volt
Your Turn
Answer
10 X 1 = 10 Volts
Can You Duplicate These
Answers?
(T5D-09)
Two Kinds of Electric Current
Typical for
Battery
Voltage is steady
And does not change
Current Flows
One Way
Called Direct Current (DC)
Voltage goes up and down
Like a wave
Current Changes direction each time
Called Alternating Current (AC)
Like the Outlet
in your house
Test Question
Did You Get It Right?
How About This One
Answer
The Voltage on Alternating Current
Looks Like a Wave
Every Time the Voltage Changes
Sign the Current Changes Direction
The number of times the current changes direction in a second is the frequency
(in the U.S. its 60 times per second)
Resisting Flow in an AC Circuit has
a Special Name
In a DC circuit we just
Call it Resistance
It has units of Ohms
“Ohm My”
In an AC circuit we call it “Impedance”
It still has units of “Ohms”
See If You Can Get This.
Most VHF / UHF Trancievers
Use Direct Current
That’s why you can hook them to
A battery or plug into a cigarette lighter
Most run on 12 volts
Connecting a Mobile
Powering Your Base Station Radio
Battery
Tender to
Keep your
Battery charged
Can also run your
Base station with
A plug in power
supply
Battery to Power
Your Radio
Plugs into your wall outlet
Puts out DC power for
Your radio.
Thoughts on Which Way to Go
• We favor the battery
– If the power goes out – so does your power
supply
• Some People like power supplies because
they fear children will get into batteries or
that battery charging will generate
hydrogen.
Slow charger with even
Remotely good ventilation
And I just can’t see the
Hydrogen issue.
A $7 to $10 battery box and some duct
Tape will keep most kids out.
What if My Battery Still Goes
Dead in an Emergency?
Power Supplies to Provide Nice
Even Power
A Bit About Power Supplies
Your household current is AC
But your Radio runs on DC
How does that happen?
A special type of circuit called a “rectifier”
More on the Power Supply Miracle
My household current is 120 volts
My radio needs 12 volts
How did that happen?
The power supply includes a regulator to control the output voltage
Features on Power Supply And
Other Places
Not All Power Supplies Are
Created Equal
I can buy this for $40 bucks – a battery and charger will cost me $95
Check the spec. – How many amperes will it put out?
A base station draws around 12 to 16 amps when you transmit
Houston – we have a problem!
Don’t Get Snookered
Oh Cool Man!
This one has 500 and is just
$50
It has 500 what?
Watts – a measure of power
Watts = Voltage * Amperage
This supply is for a computer – its output voltage is about 5 volts – not 12 volts
Some supplies will express output in watts – if they do you have to check output
Voltage and then calculate the amperes
Suggestion
Don’t buy anything less than a 20 amp power supply.
But I’m Going to Run a Baofeng
Handheld on Batteries.
Your radio is only good as long as the battery lasts
You can buy extra batteries
And the battery will fit in the
Charger without the radio.
Hey I Found this Extra Large
Battery on Amazon
Yes – but this bump means it won’t fit on most Baofeng Radios
You can whittle the offending bumps down with a dremel tool – U Tube
Videos are available – if you want the hassle.
Here is a Case I Can Put 6 AAA
batteries in
Not all batteries are rechargable!
Ni – Metal Hydride (Ni-MH)
Are rechargable
Lithium Ion are rechargable
(your cell phone and computers use
These)
The old carbon-zinc and alkaline
Batteries are not.
Try the Questions
(This is a fancy rechargeable for base stations)
Some Things Are Easier for
Electricity to Go Through
Things that let electricity go through
are called conductors.
Like the Copper
Wire in your
House
(most metals are conductors)
Some Things are Hard
Things that stop electric
Signals are insulators
(Things like plastic and
glass are insulators)
Basic Electric Components
The resistor – it resists the flow of electricity
One Use for a Resistor
Variable resistor is called a potentiometer. It can be used control volume
(Remember – the height of a wave or amplitude determines how much power is in the wave – resistors can control
Amplitude)
I Bet You Can Get This One
A potentiometer is a variable resistor - what do you think a potentiometer changes?
Another Component
Insulator
The Capacitor is two electrical plates
Separated by an insulator. (T6A-05)
It can accumulate charges on the
Plates and store energy in an
Electric field. (T6A-04)
The capacity to store energy in an
Electric field is called “Capacitance”
(T5C-01)
Two Plates Give You the
Capacitance for Advertizing
Capacitors
Capacitors are very fair devices
In fact their capacitance is only measure in “Fair Ads” (Farads)
The Basic Unit of Capacitance is the Farad (T5C-02)
Another Component
The Inductor
An Inductor is usually composed of a
Coil of wire. (T6A-07)
The ability to store energy in a magnetic
field is called “inductance” (T5C-03)
The type of component that stores
energy in a magnetic field is an inductor
They store energy in a magnetic field
(T6A-06)
What is the Name of the Duck?
Henry
Henry
The Basic Unit of Inductance
Is the Henry! (T5C-04)
Using Capacitors and Inductors
Together
Inductors and Capacitors
Work together to let you
Tune an electric circuit
To a particular frequency
Of Course No Circuit Would Be
Complete without This!
Do You Always Have to Flip
Switches by Hand?
You can actually flip a switch with an
electromagnet
A switch controlled with an electromagnet is
Called a relay (T6D-02)
Don’t Blow a Fuse
Fuses Protect other electrical components from current overload (T6A-09)
Changing the Voltage
120 volts is just too much
For your computer.
Transformers are used to increase or decrease voltage
The Semi-Conductor
A conductor will allow electricity
To go through
An insulator will not allow
Electricity to go through
A semiconductor will allow
Electricity to go through only under
Certain conditions.
An example is a diode that allows electricity to flow in only one
Direction.
Which Way?
You can flow positive to negative
But you have to use electron terms
Anode + Cathode –
(note they are in alphabetical order)
How Can You Tell Which End is
Which
They put a band or Stripe on the
Cathode Side
Checking to Make Sure Your
Awake!
Your Turn
(T6B-06)
Did You Get It?
Stripe on the Cowthode Side
The Amazing Transistor
It is made of 3 layers of semiconductor material
It can use the voltage or current in one circuit to control what it will let current in
Another circuit do.
What can I do with that?
I can use a transistor to amplify a signal
Or even turn it off all together.