Electronics Flashcards
How many electrons are in the outer shell?
8
What are covalent bonds?
Chemical bond of sharing electron pairs between atoms
What are valence electrons?
Electrons in the outer shell that can be shared with other atoms to form covalent bonds
How many electrons do the best conductors have in their outer shell?
1-3
How many electrons do the best insulators have in their outer shell?
5-8
How many valence electrons do semi conductors have?
4
What is doping?
Process of adding small impurity to semiconductor to make N type or P type
What is an N type seni conductor?
Has a material with 5 valence electrons introduced to it, outer 4 valence electrons create covalent bond leaving one extra electron to move around freely. There is an excess of Negative electrons hence the N.
What is a P type semi conductor?
A material with 3 valence electrons is introduced to a semi conductor, the outer valence electrons create a covalent bond with the 3 valence electrons of the new material leaving one hole available. This makes this semi conductor more Positive, hence the P
What is negative temperature coefficient
As temperature increases, resistance decreases, current increases.
What is built into diodes to dissipate heat?
Heat sink fans
What is a diode made of?
A P type and an N type semiconductor
What is the name and polarity of the P type semi conductor?
Anode, positive.
What is the name and polarity of the N type semi conductor?
Cathode, negative
Voltage drop across reverse and forward bias diodes
Reverse: will read source, acts as an open
Forward: silicon: 0.7V, Germanium: 0.3V
Resistance of reverse and forward bias diodes
Reverse: infinite, will not conduct
Forward: zero, will conduct easily with very little voltage drop
What type of switch is a diode?
Solid state switch
When does breakdown voltage occur?
When PIV is surpassed
What is PIV?
Peak inverse voltage. Max voltage diode can safely block. If value is passed the diode will start to conduct very high current and destroy itself (breakdown voltage)
Forward Current Rating:
Max RMS current value that diode can safely handle without damage.
Zener diodes conduct in reverse or forward bias?
Forward.
Why are Zener diodes used as voltage regulators?
In reverse bias they are able to change their resistance to maintain constant voltage over a range of currents.
What are zener diodes rated in?
Watts
Term for turning AC into DC
Rectifier
Term for turning DC into AC
Inverter
Formula for finding Eavg on a half wave circuit
Epeak / pi
Formula for finding Eavg on a full wave
Epeak • 2 / pi