Electrical Flashcards
What are copper losses
How to show them
Power loss due to reisstance in windings + leakage of inductance in windings
Series resistor Inductor (draw diagram)
What are iron losses
Losses due to hysterics , eddy currents, and loss in flux
Parallels inductor and resistor
How to measure copper loss
How to measure iron loss
Shirt circuit test, impedance federal and the. Use the rated current and powers (disregard the iron loss )
Open circuit test , (disregards copper loss) and use rated voltage along with power
Why cmos better than nmos 2 points
Only consumes power when switching stats
But only transistors, no need to use any resistors so much smaller
thevinin theroem
as far as load is concerened, a linear circuit may be represented by an ideal voltage source Vth in series with a resistor Rth,
where VTh is Voc and RTH is Voc/ Isc
norton theroem
as far as load is concerned, a linear circuit can be replaced by an ideal current source IN in parallel with a resistor RN
where IN is given by Isc and RN Voc/ Isc
no load = not possible + can do thev / norton to the entire circuit at once
ideal opamp assumptions (3)
- infinite open loop gain A
- infinite input impedance
- 0 output impedance
why is it assumed for metallic conductors that there any net charge is distributed on the surface only
by gauss law, if there were any charge inside the conductor there would be an electric field, which would casue such charges to surface of the conductor , such that the internal net electric field would become zero
self inductance defined
fluz linked of cicuit / current
method for capacitance
1) make inner circle a +q, and +v, outer -q and ground, then its really easy
purpose of source follower
high input impedance low output impedance and drives high current, so expect r2 to be much smaller
assumptions for flux conservation
no fringing effects , distance too small
virtual work derivation
in order to maintain electrostatic equilibroum a force is acted on the two charged objects
moving a charged object
- attractive force F is balanced by restoring force -F which we want to find.
- this does mech work -Fdx
- requires work from battery v dq ( use voltage equation is w/q)
- and results in a change of electrostatic energy 0.5 VQ (area under qv grah)
- equate and differntiate
why does virtual work show that only the force depends on mutual inductance
this becasue the self inductance terms are definitely constant, so it must depend on the Mi1i2 term only
the only change in energy as vf is dw/dx is due to M which changes with x
max power output transfer thereom for amplifiers
is v out sqaured/ rL, or better I sqaured RLdifferentiate wrt to Rl set to 0, happens when RL= R total output impedance
what are coupling and bypass caps used for in amplifiers
c1 coupling prevents the dc component of the output from the preivous circuit from entering so it doesnt mess up the dc biasing and c2 blocks its own dc
cs is a bypass capacitor that tries to increase the gain which is limited by vs, but vs is needed to bias the circuit. at dc f is low so open circuit but when ac f is high then short
how does tuning work
one frequency is chosen to be amplified whilst the rest attenuated. hence capacitance and inducantce chosen so that at specific f it will go to resosnance cancelling these terms leaving resisitive only an dgain hella high
so at tuning selected f is resonance
What does 2s complement mean
Us a coding of binary number that allows representation of negative numbers for an 8 bit word
0-127 are the positive range = which is the same as unsigned
-128 to -1 is the negative range
- the negative numbers are converted to 2s complement by inverting snd adding 1
Significance of 2s complement
Normal binary arithmetic csn be used , no separate CIRCUITD are needed to add negative numbers
What’s in jk nit in sr ( 3 things and state their advantages)
-Jk is master slave with clock , which means clock must switch from los to high for input of master to affect output of slave
- a clock common to both master and slave avoids the propagation of delays
- s=r=1 is forbidden now, and j=k=1 is a toggle
- also preset and clear bar allows for output to be changed irrespective of inputs, being active low
Why better to have more gates
- breaks down circuit into smaller manageable chunks to test and debug
- can add more functions
So does Tristan’s allow microprocessor to read and write data i
If Trista tell on or off due to if chip select / read or write on or off, it will either activate the date out or data in
Explain difference between file register instructions and literal instructions
Literal = instructions operate on constant data embodied directly within thr isntruction itself
FILE REGISTER instructions = operating e on data located in the file register of the pic microprocessor memory, their argument is in the address of the file register where the data is stored
When is there dc
When 1+1 occurs in 3rd bit
What is standard DAC and it’s drawback
KPa p ideal so temrknak virtual
Voltages at each point contribute currents that make up final voltages
- not ideal because resistors different values different materials TEMPERTAURE variation
Accuracy is crazy
Needs a lot of resistors
How to do day voltsge
Whatever number they give that’s the max voltsge
Find currents and multiply
Check the rail of opamp, it will, be that sign
How to do max range q for memory chip
3 lines means 4 bits at the front to give 8 locations
Start that from 0 to 7 to give 8
Then for each chip the min is 0 for the rest and 1 for all
Then represent in he’s
