Basic Electronics
ELECTRONIC BASICS
Persons new to electronics can have difficulties with the component values and
descriptions. Here are some guidelines for resolving these problems.
a) Basics
b) Resistors
c) Capacitors
d) Diodes
e)Transistors
f) IC's
Basics
The most often used terms in electronics are voltage and current
To give you a metaphor for this you can think of a river.
The voltage is the length of the river and the current can be seen the current of the river.
This current is due the difference in height between the start and end of the river.
One law you have to remember is law of Ohm. (See OHM’S LAW). It is a simple law.
Voltage = Current * Resistance
or U = I * R
Where voltage is in voltage [V], current in Ampere [A] and the resistance in
Ohm.
To make it easier for you to make conversions I will provide you [literally] a
rule of thumb.
Voltage [V]
-------------------------------
Current [i] * Resistance [Ohm]
Now just place your thumb over the unknown value and you will see what you have
to do to find the value. For example. If you want the know the resistance then
you have to divide the voltage by the current.
Numbers can become quiet large in electronics. To prevent writing many zero's
they use often different names. The following names are used.
Value, milli-, micro-, nano- and pico-
Example: Farad [capacitor] Farad, milli Farad [mF], micro Farad [uF], nano Farad
[nF], pico Farad [pF]
Every step is 1000 smaller like 1 Kg is 1000 Grams.
Resistors
Symbol
---/\/\/\/\----
or
------
---| |-----
------
A resistor can be seen as a dam in a river. Water will have more difficulties to
pass this dam. In a resistor this will result in the generation of heat.
Resistors come in standard values to choose from. The value of a resistor can be
found with the help of a colour table. The resistor has a set of coloured rings
that will tell you its value.
First ring : First number
Second ring : Second number
Third ring : Number of zeros to add
Fourth ring : Tolerance [quality of the resistor. Mostly 5%]
1 Brown Examples:
2 Red 4700 Ohm 1 000 000 Ohm
3 Orange Yellow Purple Red Brown Black Green
4 Yellow
5 Green
6 Blue
7 Purple Brown Black Brown Red Red Red
8 Grey 100 Ohm 2200 Ohm
9 'White'
0 Black
Values are often written as 10K, 1M or 4K7. This means in this case 10.000,
1.000.000 and 4700 Ohm. The 'K' just stands for Kilo and tells you that there is
a factor 1000 there. The 'M' stands for mega and adds another factor 1000
Capacitors
\
Symbol
||
---||---
||
A capacitor can have more functions but one of them is to store some energy in
them. They act like a bucket. You can fill them with energy and drop the
contents back when you need it.
Values are often written as 10N or 2N2. This means in this case 10.000 and 2200
nano Farad. The 'N' just stands for nano. Small capacitors can have only numbers
on them like 104. The first two digits is a number and the third digit tells you
how many zeros you must add. In this case its four. The correct value of this
component is 100 000 pF. [note: 100 nF or 0.1uF is also correct]
Diode
Symbol
|\ |
___| \|___
| /|
|/ |
Diodes are the passive one-way locks in the river. Water can flow through them
only in one direction. And only when there is enough difference in height
[voltage].
Knowing this you may notice that a diode needs to have a direction to function.
To show this there is a small mark at the casing. Normally this is a ring. For
LED this isn't the case. You have to look inside and see the small plates. The
one with the largest plate is the side where the 'ring' would be.
Transistor
Symbol
| /c c = collector
___|/ b = basis
b |\ e = emitter
| \e
These are the active locks in the river. They have a lock gate that can control
the flow through them. They can also act like a switch. With a little current
they can be opened and let a strong current pass. In the symbol there is also a
arrow that will tell you the direction of flow. There are two basic transistor
types namely; PNP and NPN. They are named to differentiate between different internal designs. A PNP has a symbol with the arrow pointing inwards and a NPN
transistor has a arrow pointing outwards.
IC (Intergrated Circuit)
Symbol
An IC doesn't have a universal symbol.
It all depends on its use. A few
examples are shown here.
|\ +---+
___| \___ -| & |
| / -| |-
|/ +---+
A little box that contains many small components as above. A complete circuit
can be inside the black plastic casing.
They have often 8, 14 or 16 pins.
They are used for many purposes. The casing has a small notch on top of it or carved
out of it.
If you look at this mark and holding the mark on top then the first
lead on the right side will be pin number one.
oldering Techniques How important is soldering?
Among the foremost of reasons an electronic project frequently fails to work
properly is due to "poor" soldering practices. This is usually caused by "dry
joints" when soldering. Here we discuss the correct procedures for soldering
electronic projects.
Dry joints when soldering
At first glance many solder joints appear to be quite "O.K." but on closer
examination many are in fact defective. The insidious problem with dry joints in
soldering is that the circuit frequently performs alright for a period of time,
even years before failure.
This problem even occurs with manufactured equipment. Ask any TV / Video repair/Cell Phone technician who has torn a lot of hair out over an elusive fault ultimately traced back to a dry joint.
Good soldering practices for your electronic project
The cause of dry joints in soldering is mostly the improper application of heat.
Both the component leg and the PCB need to be both heated simultaneously to the
correct temperature to allow the solder to flow freely between BOTH surfaces.
Obviously this requires practice and most newcomers inevitably get it wrong.
Improper heating while soldering and its consequences can be seen below.
Figure 1 - correct soldering procedures to avoid dry joints
Here in figure 1 entitled "correct soldering procedures to avoid dry joints" we
have three examples of soldering depicted.
The first example indicates the component lead was heated while the PCB wasn't heated.As a consequence the solder only flowed onto the component lead.
In the second example of soldering in figure 1 we find the PCB was correctly
heated while little or inadequate heat was applied to the component lead. This
is the most treachorous example because although I have made it very obvious in
the diagram, in practice it is not always particularly obvious.
Often this type of dry joint "just" allows the solder to "touch" the component lead while not actually being "soldered" to the lead. Of course it might work for a period of time depending upon environmental conditions of heat and cold.
In the final example of "correct soldering procedures to avoid dry joints" We
have depicted the solder bridging both the PCB and the component lead.
In this case the PCB and the component lead were both heated "simultaneously" AND the solder was applied to either the component lead or the PCB to "flow" freely from one to the other to provide a good "electrical" joint. Such a joint is always "bright and shiny", dull looking joints are often suspect.
You never apply the solder to the soldering iron "tip". Solder is always applied
to the "job", never the soldering iron. Allow the solder to "set" and cool
before proceeding to the next joint.
Other cases of soldering
We have discussed soldering components to a PCB yet this is not the only case of
soldering. Often we need to connect wires to switches and other components. A
common misconception is that soldering is designed to provide a good mechanical
joint. - It isn't!
Any connection should have it's own mechanical strength perhaps by twisting
wires together or twisting the wire around a binding post or through a hole
provided for the purpose.
The solder is only intended for a good "electrical" connection. Never provide a connection which can't stand mechanically on it's own merits.
What's soldering flux?
Modern quality electronics solders contain a "flux" resin within the solder.
This flux is designed to flow over the job and prevent contact with the
atmosphere.
Metals, particularly copper when heated tend to "oxidise" and prevent the alloying or good electrical bond between the copper and the solder.
Good solder containing the resin will have resin flowing over the leads and
prevent this oxidisation process and as the solder flows the resin is displaced
allowing the solder to form an "atomic" bonding with the items being soldered
together. A good resin helps to keep the surfaces clean.
Rules for good soldering
Of course some of these rules might seem very obvious but are worth repeating.
Use a reasonable quality iron of the correct wattage for the job.
Only use "electronic" resin cored solder of fine gauge.
Make sure all surfaces to be soldered are "bright, shiny" and thoroughly
clean.
If a mechanical joint, make sure it can "stand alone" before soldering.
Make sure the solder tip is clean, shiny and properly "wetted".
Remember the soldering iron tip is only to heat up the surfaces to be
soldered.
Apply the resin cored solder to the heated "job", not to the soldering iron
tip.
Remember to visually inspect ALL of your soldered joints, preferably with
magnifying glasses.
Consider using your multimeter to provide an "electrical continuity" check
between various parts of the circuit.
[Image][Image][Image][Image]
Persons new to electronics can have difficulties with the component values and
descriptions. Here are some guidelines for resolving these problems.
a) Basics
b) Resistors
c) Capacitors
d) Diodes
e)Transistors
f) IC's
Basics
The most often used terms in electronics are voltage and current
To give you a metaphor for this you can think of a river.
The voltage is the length of the river and the current can be seen the current of the river.
This current is due the difference in height between the start and end of the river.
One law you have to remember is law of Ohm. (See OHM’S LAW). It is a simple law.
Voltage = Current * Resistance
or U = I * R
Where voltage is in voltage [V], current in Ampere [A] and the resistance in
Ohm.
To make it easier for you to make conversions I will provide you [literally] a
rule of thumb.
Voltage [V]
-------------------------------
Current [i] * Resistance [Ohm]
Now just place your thumb over the unknown value and you will see what you have
to do to find the value. For example. If you want the know the resistance then
you have to divide the voltage by the current.
Numbers can become quiet large in electronics. To prevent writing many zero's
they use often different names. The following names are used.
Value, milli-, micro-, nano- and pico-
Example: Farad [capacitor] Farad, milli Farad [mF], micro Farad [uF], nano Farad
[nF], pico Farad [pF]
Every step is 1000 smaller like 1 Kg is 1000 Grams.
Resistors
Symbol
---/\/\/\/\----
or
------
---| |-----
------
A resistor can be seen as a dam in a river. Water will have more difficulties to
pass this dam. In a resistor this will result in the generation of heat.
Resistors come in standard values to choose from. The value of a resistor can be
found with the help of a colour table. The resistor has a set of coloured rings
that will tell you its value.
First ring : First number
Second ring : Second number
Third ring : Number of zeros to add
Fourth ring : Tolerance [quality of the resistor. Mostly 5%]
1 Brown Examples:
2 Red 4700 Ohm 1 000 000 Ohm
3 Orange Yellow Purple Red Brown Black Green
4 Yellow
5 Green
6 Blue
7 Purple Brown Black Brown Red Red Red
8 Grey 100 Ohm 2200 Ohm
9 'White'
0 Black
Values are often written as 10K, 1M or 4K7. This means in this case 10.000,
1.000.000 and 4700 Ohm. The 'K' just stands for Kilo and tells you that there is
a factor 1000 there. The 'M' stands for mega and adds another factor 1000
Capacitors
\
Symbol
||
---||---
||
A capacitor can have more functions but one of them is to store some energy in
them. They act like a bucket. You can fill them with energy and drop the
contents back when you need it.
Values are often written as 10N or 2N2. This means in this case 10.000 and 2200
nano Farad. The 'N' just stands for nano. Small capacitors can have only numbers
on them like 104. The first two digits is a number and the third digit tells you
how many zeros you must add. In this case its four. The correct value of this
component is 100 000 pF. [note: 100 nF or 0.1uF is also correct]
Diode
Symbol
|\ |
___| \|___
| /|
|/ |
Diodes are the passive one-way locks in the river. Water can flow through them
only in one direction. And only when there is enough difference in height
[voltage].
Knowing this you may notice that a diode needs to have a direction to function.
To show this there is a small mark at the casing. Normally this is a ring. For
LED this isn't the case. You have to look inside and see the small plates. The
one with the largest plate is the side where the 'ring' would be.
Transistor
Symbol
| /c c = collector
___|/ b = basis
b |\ e = emitter
| \e
These are the active locks in the river. They have a lock gate that can control
the flow through them. They can also act like a switch. With a little current
they can be opened and let a strong current pass. In the symbol there is also a
arrow that will tell you the direction of flow. There are two basic transistor
types namely; PNP and NPN. They are named to differentiate between different internal designs. A PNP has a symbol with the arrow pointing inwards and a NPN
transistor has a arrow pointing outwards.
IC (Intergrated Circuit)
Symbol
An IC doesn't have a universal symbol.
It all depends on its use. A few
examples are shown here.
|\ +---+
___| \___ -| & |
| / -| |-
|/ +---+
A little box that contains many small components as above. A complete circuit
can be inside the black plastic casing.
They have often 8, 14 or 16 pins.
They are used for many purposes. The casing has a small notch on top of it or carved
out of it.
If you look at this mark and holding the mark on top then the first
lead on the right side will be pin number one.
Soldering Techniques
oldering Techniques How important is soldering?
Among the foremost of reasons an electronic project frequently fails to work
properly is due to "poor" soldering practices. This is usually caused by "dry
joints" when soldering. Here we discuss the correct procedures for soldering
electronic projects.
Dry joints when soldering
At first glance many solder joints appear to be quite "O.K." but on closer
examination many are in fact defective. The insidious problem with dry joints in
soldering is that the circuit frequently performs alright for a period of time,
even years before failure.
This problem even occurs with manufactured equipment. Ask any TV / Video repair/Cell Phone technician who has torn a lot of hair out over an elusive fault ultimately traced back to a dry joint.
Good soldering practices for your electronic project
The cause of dry joints in soldering is mostly the improper application of heat.
Both the component leg and the PCB need to be both heated simultaneously to the
correct temperature to allow the solder to flow freely between BOTH surfaces.
Obviously this requires practice and most newcomers inevitably get it wrong.
Improper heating while soldering and its consequences can be seen below.
Figure 1 - correct soldering procedures to avoid dry joints
Here in figure 1 entitled "correct soldering procedures to avoid dry joints" we
have three examples of soldering depicted.
The first example indicates the component lead was heated while the PCB wasn't heated.As a consequence the solder only flowed onto the component lead.
In the second example of soldering in figure 1 we find the PCB was correctly
heated while little or inadequate heat was applied to the component lead. This
is the most treachorous example because although I have made it very obvious in
the diagram, in practice it is not always particularly obvious.
Often this type of dry joint "just" allows the solder to "touch" the component lead while not actually being "soldered" to the lead. Of course it might work for a period of time depending upon environmental conditions of heat and cold.
In the final example of "correct soldering procedures to avoid dry joints" We
have depicted the solder bridging both the PCB and the component lead.
In this case the PCB and the component lead were both heated "simultaneously" AND the solder was applied to either the component lead or the PCB to "flow" freely from one to the other to provide a good "electrical" joint. Such a joint is always "bright and shiny", dull looking joints are often suspect.
You never apply the solder to the soldering iron "tip". Solder is always applied
to the "job", never the soldering iron. Allow the solder to "set" and cool
before proceeding to the next joint.
Other cases of soldering
We have discussed soldering components to a PCB yet this is not the only case of
soldering. Often we need to connect wires to switches and other components. A
common misconception is that soldering is designed to provide a good mechanical
joint. - It isn't!
Any connection should have it's own mechanical strength perhaps by twisting
wires together or twisting the wire around a binding post or through a hole
provided for the purpose.
The solder is only intended for a good "electrical" connection. Never provide a connection which can't stand mechanically on it's own merits.
What's soldering flux?
Modern quality electronics solders contain a "flux" resin within the solder.
This flux is designed to flow over the job and prevent contact with the
atmosphere.
Metals, particularly copper when heated tend to "oxidise" and prevent the alloying or good electrical bond between the copper and the solder.
Good solder containing the resin will have resin flowing over the leads and
prevent this oxidisation process and as the solder flows the resin is displaced
allowing the solder to form an "atomic" bonding with the items being soldered
together. A good resin helps to keep the surfaces clean.
Rules for good soldering
Of course some of these rules might seem very obvious but are worth repeating.
Use a reasonable quality iron of the correct wattage for the job.
Only use "electronic" resin cored solder of fine gauge.
Make sure all surfaces to be soldered are "bright, shiny" and thoroughly
clean.
If a mechanical joint, make sure it can "stand alone" before soldering.
Make sure the solder tip is clean, shiny and properly "wetted".
Remember the soldering iron tip is only to heat up the surfaces to be
soldered.
Apply the resin cored solder to the heated "job", not to the soldering iron
tip.
Remember to visually inspect ALL of your soldered joints, preferably with
magnifying glasses.
Consider using your multimeter to provide an "electrical continuity" check
between various parts of the circuit.
[Image][Image][Image][Image]
