Introduction to Electronics:
Current: A flow of electrical charge through a conductor. Measured in Amperes or
AMPS. The term AMP is used to measure the flow rate of a charge through a circuit.
The word Ampere is derived from the name of the person that first invented a means of
measuring electricity Andre Marie Ampere (@1825). Current is represented in electrical
calculations by the letter I.
Direct Current or DC is when the current always flows in the same direction.
Examples of DC Power is anything that uses a battery to operate.
Alternating Current or AC is current that changes in capacity and direction of
flow. The change is caused by the constant change in polarity at the voltage
source. Examples of AC Current is the plugs, lights, appliances, etc at your
home or office.
The change of the AC Wave is called FREQUENCY, and it is measured in cycles
per second, or Hertz. In North America, our power alternates at 60 Cycles per
second or 60 Hertz (Hz). You might also hear The terms Kilo Hertz (KHz), Mega
Hertz (MHz) or Giga Hertz (GHz). The term Hertz is derived from the name of
the person that developed the first system of measuring frequency, Heinrich
1000 Hz = 1KHz
1000 KHz = 1MHz
1000 MHz = 1GHz
Voltage: The force needed to move an electrical charge (current) through a circuit.
Voltage is measured in Volts AC or Volts DC. The term voltage is derived from the
name of the person that invented the first battery Alessandro Volta (@1800). Voltage is
represented in electrical calculations by the letter E.
Like water, voltage always takes the past of least resistance, so it always flows
toward the spot with the least number of electrons. This is also why it is possible
for a person to get electrocuted.
Voltage is created by Generators, Batteries, Electro-Static Force, Heat, Photo
Cells, or Mechanical Energy.
Power is the rate of electricity working, and it is measure in WATTS. Power is
represented in electrical calculations by the letter P. To calculate Power, we multiply the
Voltage (E) x Current (I) and we get Power or WATTS (P).
At this point, we now know that:
I = Current (Amps) = FLOW
E = Voltage (Volts) = PRESSURE
P = Power (Watts) = HEAT
R = Resistance (Ohms) = Friction
Now, how do they all relate to each other ???????
The Power Equation:
E = P/I I= P/E P= E x
Any force which limits the flow of electric current in a circuit. Resistance is measured in
Ohms. The term OHM’s is derived from the person who first recognized the relationship
between Voltage, Current, and Resistance (know more commonly as OHM’s LAW),
Gerg Simon Ohm.
OHM’s Law States:
E=IR R=E/I I=E/R P=EI P=E2/R P=I2R
HEAT is the major enemy of an electronic circuit. Power and Resistance generate heat.
Put a bunch of components together, and you have one serious heater. Almost every
component you come in contact with will have Storage and Running temperature
guidelines and limits. Much of an electronics engineer’s time is spent designing in
components to remove the heat from a piece of equipment.
Up to this point, we have discussed electricity in it’s most basic state. This is not all
inclusive, but for the purposes of sales, will more than equip you for daily calls. This
does not have to be committed to memory. We cover this information so that you will be
exposed to it, and if you happen to hear any of it referenced while speaking to a
customer, it will not be completely foreign to you.
All of your factories have trained engineers to help us and our customers with technical
issues, and they can be called upon to do this at any time.
Electronic Components are all around us. When we watch TV, use a Microwave Oven,
Set the Thermostat in our house, Drive our cars, there are thousands of electronic
components working to make each device operate.
Most of the components AtCom sells are known as either PASSIVE or ELECTO-
MECHANICAL. Capacitors, Resistors, Thermistors, Fuses, and Thermal Fuses are all
Passive Components. Snap Action or Bi-Metal Switches, Power Switches, Circuit
Breakers, and Heatsinks are all considered Electo-Mechanical. Products from a line like
Powerex are considered to be ACTIVE because IGBT’s, Diodes, Thyristors, Rectifiers,
SCR’s are all silicon or Semiconductor based. Some other types of components are: ,
Electromagnetic, like Inductors, Transformers and Electro-optical like LEDs, and IR
All electronic components are basically made to alter, control or produce electricity and
when working together, perform some type of function.
Capacitors: Store Electrical Energy
Resistors/Thermistors: Limits the flow of current in a circuit
Transformers: Increase or Decrease the amount of electricity
Fuses/Circuit Protection: Prevent runaway electricity
Switches & Relays: Turn electrical current on or off
Diodes & Transistors: Control the flow of electricity
Power Supplies: Convert, Regulate, or invert electricity
Displays & Lamps: Change electricity into visible information
Optoelectronics I/R or Visible: Light Something, detect the presence or
strength of light, the position of something, or to transmit a signal
IC’s are in essence a combination of two or more of the above devices
Batteries: Produce electricity
Most of the components we sell are mounted on Printed Circuit Boards (PCBs).
A PCB is basically a piece of non-conductive material, like fiberglass (usually called a
substrate) that has strips of conductors printed on it, which connect electronic
components, creating a circuit. Although the PCB only has two sides, top & bottom, it is
possible to print many layers of circuits in between the different layers of substrate. The
process of printing the conductor strips onto the substrate is very similar to the process
used to screen print images onto T-Shirts. There are holes or pads that are also printed
on the PCB that serve as the termination point for components. PCB’s are used instead
of wiring components together, and greatly increase the efficiency of a circuit, while at
the same time decreasing it’s cost and size. Most low voltage circuits, and some high
voltage circuits are laid out on PCB’s.
Some of the components we sell go into higher voltage applications, and as a result, are
not intended for use on PCB’s. In most cases, circuits running at higher voltage are still
terminated using wires or laminated buss bars. Using wires as interconnects is basically
the same principal as wiring in your home. Buss bars are basically strips of metal that
are laminated together, and then bolted between components as a means of connection.
The two most popular methods of attaching components to a circuit board are:
Through Hole or Thru-Hole: Components are mounted through plated holes in
the substrate, on the top or bottom of the PCB and soldered into place.
AXIAL: Leads come out of the component on opposite ends.
RADIAL: Leads come out of the component on the same end.
Surface Mount or SMT or SMD: Components are mounted on solder pads either
on the top or bottom sides of the PCB and soldered into place. You will hear all
kinds of abbreviations describing surface mount parts (SOP, SOIC, SOJ, TSOP,
SSOP, QFP) but mostly in the semiconductor world. In our business, the most
common types of SMT are:
CHIP: Flat square or rectangular package with solder pads on two sides
Gull Wing / J – Lead: Is very similar to a Thru-Hole packager, but the
leads are bent or altered to create an SMT part.
MELF: A round, barrel like package with solder pads printed around the
outer most edges.
Other Helpful Information:
Unit of Measure Prefixes:
When dealing with Capacitors, Resistors, Thermistors, Induductors, and almost every
other component, you will hear the following prefixes used in conjunction with their
respective unit of measure. This is done to simplify the system. For example Giga
Ohm, Giga Hertz, Mico Farad, etc.
Instead of printing 2,000,000 ohms – it is abbreviated to 2M
Prefix Symbol Actual Digits Scientific Form
Tera T One Trillion times 1,000,000,000,000 10
Giga G One Billion times 1,000,000,000 10
Mega M One Million times 1,000,000 10
Kilo k One Thousand times 1,000 10
Milli m One Thousandth .001 10
Micro u or µ One millionth 0.000001 10
Nano n One billionth 0.000000001 10
Pico p One trillionth 0.000000000001 10
Most electronic components have a tolerance spec. This is the allowed variation from a
specified value that the part can have, and still be considered within the specifications.
Often times you will see +/- before the tolerance, and sometimes it is expressed as a
number with the percent sign after it.
In addition, there are also standard industry codes that are used to represent the
tolerance. F=1%, G=2%, J=5%, K=10%, M=20%. There are others, but those are the
A Metal Film Resistor that is called out as a 2.5K ohm will have a resistance tolerance of
1%. That means that the part can actually read between 2475 and 2525 ohms, and still
be within spec. A general rule of thumb – the tighter or lower the tolerance is, the more
expensive the component will be.
Lead spacing is another term that runs across many different component types. This
basically is a measurement, usually expressed in millimeters, from the centerline of one
lead to the centerline of another lead. The industry has done a lot to create standard
lead spacing on many components, but there are some exceptions.
Packing or Packaging Type:
Electronic components are packaged in many different ways. The most common
BULK or BULK PACK: Parts are packed loose in boxes.
Tape & Reel*: Parts are packed by attaching the leads together with tape,
and then spooling them around a reel.
Ammo Pack*: Same as Tape & Reel, but instead of spooling around a
reel, the tape is folded end to end and put into a box.
Tube*: Parts are packed into plastic tubes.
* These methods are used to feed electronic components automatically into a pick and
place machine. A pick and place machine places components on a circuit board
Tape & Reel and Ammo Pack packaging will have something called a LEADER STRIP
on the leading edge of the package. This allows the machine to spool up the reel.