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Activity for MissMulan‭

Type On... Excerpt Status Date
Edit Post #287366 Initial revision over 1 year ago
Question BJT common emitter amplifier equivalent circuit (π hybrid model)
Im studying the equivalent model of a BJT common emitter amplifier at high frequencies.At university we tought that the BJT at high frequencies looks something like this: ![](https://electrical.codidact.com/uploads/MAzybbLAUC9WM7AGPwrHAGAo) However when designing a common emitter amplifier we h...
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over 1 year ago
Comment Post #287302 Andy hi. I was taught it in university yesterday and I didn't understand it.
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over 1 year ago
Edit Post #287302 Initial revision over 1 year ago
Question Thermal stability coefficient
The thermal stability coefficient is defined to be: $S = \frac{dI{C}}{dI{CBO}}$ where $I{CBO}$ is the reverse current of the BJT when voltage isnt applied to the base of the BJT. In case of a BJT biased with 2 sources $I{C} = \beta \cdot I{b}+(\beta +1)I{CBO}$ However my textbook says that \$...
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over 1 year ago
Edit Post #286859 Initial revision over 1 year ago
Question Circuit which create ac sine wave from dc pulsed signal
A full wave rectifier converts a sine wave to DC pulsed signal of double frequency. Is there a circuit which does the reverse process?
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over 1 year ago
Comment Post #286836 @Elliot Alderson Editted.
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over 1 year ago
Edit Post #286836 Post edited:
over 1 year ago
Edit Post #286836 Initial revision over 1 year ago
Question Need help design a digital circuit which divides two binary numbers
Before the circuit here are the digital blocks which have been already designed and exist as part of the division block 1 bit subtractor: ![](https://electrical.codidact.com/uploads/Lhdm5UMLtxwsGoArgB5D2KZ5) 2 bit subtractor(in the digital block diagram of the division block there is a 3 bit...
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over 1 year ago
Edit Post #286792 Initial revision almost 2 years ago
Question Op Amp Hartley oscillator
Im designing a Hartley oscillator this time with a opamp providing the open-loop gain.I have tried drawing the small-signal analysis of my circuit to use KVL and KCL to find the conditions of operation of my Hartley oscillator but now I am stuck. ![](https://electrical.codidact.com/uploads/Q9Mur5T...
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almost 2 years ago
Comment Post #286784 @a concerned citizen but arent they biasing resistors part of the input impedance of the circuit ?Why are we neglecting them?
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almost 2 years ago
Edit Post #286777 Initial revision almost 2 years ago
Question Results of analysis of Hartley oscillator dont make sense
I want to find the conditions of oscillation of the following Hartley oscillator.I have attached a load (ZL) to my Hartley oscillator Image alt text I have written KCL for nodes A,B: For node A: $$\frac{V{A}}{sL{1}} + \frac{V{A}}{Z{L}}+\frac{V{A}}{R{C}}-sC{1}(V{A}-V{B})+g{m}V{x} = 0 \righ... (more) almost 2 years ago Comment Post #286765 Why do I need the IV curve?I have approximated the tunnel diode to behave like a resistor$$ R_{d} = \frac{V_{T}}{I_{s}}$$from Vf to Vv and from 0 to Vp (more) almost 2 years ago Edit Post #286760 Post edited: almost 2 years ago Edit Post #286760 Post edited: almost 2 years ago Edit Post #286760 Initial revision almost 2 years ago Question Modelling tunnel diode relaxation oscillator I have been trying to model this oscillator ![](https://electrical.codidact.com/uploads/NzcDCkE2ExtPVQnusohTcBg4) I was wondering if we can somehow predict the frequency of the oscillations.For small currents inside a diode from the Shockley diode equation$$ e^{x}-1 = x$$->$$I{D} = \frac{x}{...
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almost 2 years ago
Edit Post #286745 Post edited:
almost 2 years ago
Edit Post #286745 Post edited:
almost 2 years ago
Comment Post #286745 @#36396 Editted.
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almost 2 years ago
Edit Post #286745 Post edited:
almost 2 years ago
Edit Post #286745 Initial revision almost 2 years ago
Question DC-DC converter using Hartley oscillator and transformer
Instead of using a buck or a boost converter can we use for DC-DC conversion the circuit Im going to describe in the next lines? First we begin with a Hartley oscillator whose output is fed into a transformer with N:1 turns ratio between primary and secondary windings. Then we rectify the voltage ...
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almost 2 years ago
Edit Post #286738 Post edited:
almost 2 years ago
Comment Post #286738 @#52987 you are correct a BJT doesnt have a CE junction I used too literally the small signal analysis of the BJT.
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almost 2 years ago
Edit Post #286738 Initial revision almost 2 years ago
Question Small signal analysis of BJT in saturation region
The small signal analysis of a BJT when the BJT is in amplification mode: ![](https://electrical.codidact.com/uploads/DcSpMK6kEuo6kbcs8dxBJJvc) is easy.However what happens when the BJT is in saturation mode? ![](https://electrical.codidact.com/uploads/dCDhn8omDKAvQ8DUsXjju1Ar) Can we rep...
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almost 2 years ago
Comment Post #286730 It is a exercise I made up to learn about filters.
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almost 2 years ago
Edit Post #286730 Post edited:
almost 2 years ago
Edit Post #286730 Initial revision almost 2 years ago
Question Design high -pass filter with 2 points of the bode plot
Im designing a high-pass filter which has a gain of -8dB at half of the roll-off frequency and I am stuck ,I dont know how to continue the design. In the bode plot of that filter we have 2 points:1 is at (fc,-3dB) and the other is at (fc/2,-8dB).What information must I extract to find the transfer...
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almost 2 years ago
Comment Post #286724 @a concerned citizen it is a EE question.Why does it matter why I want to ask the question?
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almost 2 years ago
Comment Post #286721 Ya I agree Q will be really high.
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almost 2 years ago
Comment Post #286724 I am designing it for fun.
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almost 2 years ago
Edit Post #286721 Post edited:
almost 2 years ago
Edit Post #286724 Post edited:
almost 2 years ago
Edit Post #286724 Initial revision almost 2 years ago
Answer A: Band pass filter given cutoff frequency and bandwidth
My mistake was taking the third relationship $$\frac{1}{RC}$$ which says how to find the bandwidth of a parallel RLC filter but we have a series RLC filter. Now solving the system : $$LC = 100020001 , \frac{R}{L} = 2$$ gives us the correct ratio between C1 and R1 and L1 with more detail: ...
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almost 2 years ago
Edit Post #286721 Post edited:
almost 2 years ago
Comment Post #286721 No I don't mean center frequency I mean bandwidth of the pass band filter,the range of frequencies at which the attenuation is higher than - 3dB
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almost 2 years ago
Edit Post #286721 Initial revision almost 2 years ago
Question Band pass filter given cutoff frequency and bandwidth
I have decided to try design a band-pass filter with a cut-off frequency of 10kHz and bandwidth of 2 Hz. Image alt text $$\frac{1}{\sqrt{LC}} = 10001 \rightarrow LC = 1/100020001 sec^{2}$$ $$\frac{R}{L} = 2Hz$$ $$\frac{1}{RC} = 2Hz$$ Here is what I have done but if I plug the value...
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almost 2 years ago
Edit Post #286705 Post edited:
almost 2 years ago
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almost 2 years ago
Comment Post #286700 @a concerned citizen I am just trying to explain to you what is inside my head.
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almost 2 years ago
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almost 2 years ago