hello,

i have just started a distance learning hnd electronics course through a learning provider. i have to complete some coursework using microcap simulator. i have never used this simulator before and haven't looked at electronics for about a year. i have started studying again and some of it is coming back to me. i have a question which i have completed and would like some one to possibly check it for me, not do it for me but maybe point out where i went wrong. before this though, i am having a problem with micro cap.
i have tried looking at the manual but i think it would be better to get an answer to this question first. the circuit is a series RLC circuit. i have to use complex notation to find the answers, converting to polar form and so on. when the answers are found i have to make a simulation to prove it. i have a sine source component that has the values. Vs = 10sin(2000t). i dont know how to set the sine source to this value. i am happy to research it but i am having trouble finding out what it is. sin would suggest something to do with trigonometry. this probably sounds daft to you but i have havent looked at this stuff for some time and im drawing a blank.


the answers that i got for the above questions are:
a/ z = 485.41 < -87.639(degrees) //the carrot (<) is supposed to be that funny looking side ways V
b/ 20.6mA < 87.639(degrees)
c/ Vr = 0.412v < 87.639(degrees)
Vl = 0.309v < 177.639(degrees)
Vc = 9.991v < 2.361(degrees)
d/ 918.881Hz
e/ 4.33
f/ 212Hz

not sure if any of this is correct, been a while like i say.
any advice would be great!!!
many thanks
Simon

 

Well, Vs = 10sin(2000t) means that you have a sine wave that has a amplitude equal to 10V (peak) and the frequency f = ω/2Π = 2000/6.28 = 318.309Hz

Xc1 = 1/(jω * C1) = -250Ω and XL = 30Ω ---->Xtot = -220Ω

|Ztot| = 220.907Ω, θ = -84.8°

 

is there somewhere on this site that explains the 10sin(2000t) bit. also, it seems my results are way out. i followed the course work example to get my results and used an online calculator. http://www.kusashi.com/polar-polar.php

 

is there somewhere on this site that explains the 10sin(2000t) bit.

But what is there to explain?
10sin(2000t) = A sin(ωt + φ) = 10V (sin 2000t + 0°)
10 - the amplitude in Volts
2000 - the angular frequency (omega ω) in radians per second
https://en.wikipedia.org/wiki/Sine_wave

 

Hello,

im not to sure what i am doing wrong. i used an online calculator to find the polar values. i used the worked example with the calculator and got the results written in the coursework. i followed the worked example with the values from the assignment. could anyone hint where i went wrong please. i havent studied electronics for about a year and math is not my strong point. i do struggle with it. i am using an online web site, math is fun, to learn about complex numbers and that is helping.

any help or advice (not sarcy comments) would be great!!!
thanks

simon

 

Show us your work.

 

Hello

here is my working, i have tried to recreate the circuit on multisim to show the values but cant get it working properly so i think there must be something wrong with my working out. otherwise i have to go and learn multisim.
any hints, tips or advice would be great!

thanks

simon

 

What results were you getting in Multisim?

 

If you have problem wit the complex maths try using this site
http://www.wolframalpha.com/input/?i=10/(20+-+220+i)
The total current 10/(20 - j220) = 0.00409836 + j0.045082 in polar 45.2679mA < 84.8°.
Additional your modulus/magnitude for a voltage drops looks good. But you messed up with the phase for VR1, Xc, XL.
Also keep in mind that those values (results) are the peak values not RMS as you might seen in Multisim

 

i tried in multisim to do an ac analysis and got the resonant frequency and the bandwidth. so i did something right there. not sure about the phase angle with the vr vc vl, i will have to go and look at that.

thanks for your help

simon