Work Package 1 Flashcards
what are mechanical switches?
hand operated components used for making or breaking the flow of electrical current in a circuit
What does SPST stand for?
single pole single throw
what is a single pole single throw? (SPST)
the simplest type of switch, it only has one pole and one contact. It can be thrown into only one contact position.
what is the SPST available as? (2)
- Push to make switch (PTMS)
2. Push to break switch (PTBS)
what does SPDT stand for?
single pole double throw
what is a single pole double throw? (SPDT)
has one pole and two contacts and can be thrown into either of two contact positions
what does DPDT stand for?
double pole double throw
what is double pole double throw? (DPDT)
has two poles and four contacts and is the same as having two single pole double throw switches in one package.
what is the same as having two single pole double throw switches (SPDT)?
a double pole double throw
what can a DPDT be used as? (2)
- can be used for connecting two circuits at the same time
2. for reversing the polarity of electric motors
what are batteries? (2)
- safe, self-contained energy sources that convert chemical energy into electrical energy
- are available in several sizes and voltages, which have different internal properties that make them suitable for particular uses
what are the four things to consider when selecting a battery?
- the power requirements of your circuit
- its voltage and type
- the physical size of the battery
- how much you’re willing to spend
what are 5 battery types?
- zinc carbon
- alkaline
- silver oxide
- lithium (non-rechargeable)
- nickel cadmium (rechargeable)
what are resistors?
common non-polar components in electronic circuits. They are used to limit the amount of current flowing in the circuit and to set the voltage levels in certain parts of the circuit.
what is an ohm?
a unit of measurement for resistance
what do the four bands of colour on a resistor show?
their resistance value
how do you read the resistor value?
hold the resistor with the single gold or silver tolerance band on the right.
what does a silver band on the resistor indicate?
tolerance of plus/minus 10%
what does a gold band on the resistor indicate?
tolerance of plus/minus 5%
resistors with a silver tolerance band of plus/minus 10% belong in which series?
the E12 series
resistors with a gold tolerance band of plus/minus 5% belong in which series?
the E24 series
where is the maximum resistance value found?
on the variable resistor’s body
how is the resistance value of potentiometers (potential dividers) or variable resistors changed?
by moving the wiper along the resistance track
what does a current limiting resistor do?
limits the current and prevents components from being damaged.
