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# Activity for MissMulan‭

Type On... Excerpt Status Date
Edit Post #287366 Initial revision 5 months 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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5 months ago
Comment Post #287302 Andy hi. I was taught it in university yesterday and I didn't understand it.
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5 months ago
Edit Post #287302 Initial revision 5 months 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 $... (more) 5 months ago Edit Post #286859 Initial revision 8 months 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? (more) 8 months ago Comment Post #286836 @Elliot Alderson Editted. (more) 8 months ago Edit Post #286836 Post edited: 8 months ago Edit Post #286836 Initial revision 8 months 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... (more) 8 months ago Edit Post #286792 Initial revision 8 months 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... (more) 8 months 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? (more) 8 months ago Edit Post #286777 Initial revision 8 months 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: $$\frac{V{A}}{sL{1}} + \frac{V{A}}{Z{L}}+\frac{V{A}}{R{C}}-sC{1}(V{A}-V{B})+g{m}V{x} = 0 \righ... (more) 8 months ago Comment Post #286765 Why do I need the IV curve?I have approximated the tunnel diode to behave like a resistor$$ R_{d} = \frac{V_{T}}{I_{s}}$$from Vf to Vv and from 0 to Vp (more) 8 months ago Comment Post #286760 @#52987 Editted. (more) 8 months ago Edit Post #286760 Post edited: 8 months ago Comment Post #286760 @#52987 I tried but couldnt find a better image.I literally googled tunnel diode inductor relaxation oscillator.Now that I am thinking about it I will be back in a sec. (more) 8 months ago Edit Post #286760 Post edited: 8 months ago Edit Post #286760 Initial revision 8 months ago Question Modelling tunnel diode relaxation oscillator I have been trying to model this oscillator ![](https://electrical.codidact.com/uploads/NzcDCkE2ExtPVQnusohTcBg4) I was wondering if we can somehow predict the frequency of the oscillations.For small currents inside a diode from the Shockley diode equation$$ e^{x}-1 = x$$->$$I{D} = \frac{x}{... (more) 8 months ago Edit Post #286745 Post edited: 9 months ago Edit Post #286745 Post edited: 9 months ago Comment Post #286745 @#36396 Editted. (more) 9 months ago Edit Post #286745 Post edited: 9 months ago Edit Post #286745 Initial revision 9 months 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 ... (more) 9 months ago Edit Post #286738 Post edited: 9 months 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. (more) 9 months ago Edit Post #286738 Initial revision 9 months 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... (more) 9 months ago Comment Post #286730 It is a exercise I made up to learn about filters. (more) 9 months ago Edit Post #286730 Post edited: 9 months ago Edit Post #286730 Initial revision 9 months 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... (more) 9 months ago Comment Post #286724 @a concerned citizen it is a EE question.Why does it matter why I want to ask the question? (more) 9 months ago Comment Post #286721 Ya I agree Q will be really high. (more) 9 months ago Comment Post #286724 I am designing it for fun. (more) 9 months ago Edit Post #286721 Post edited: 9 months ago Edit Post #286724 Post edited: 9 months ago Edit Post #286724 Initial revision 9 months 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: ... (more) 9 months ago Edit Post #286721 Post edited: 9 months 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 (more) 9 months ago Edit Post #286721 Initial revision 9 months 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... (more) 9 months ago Edit Post #286705 Post edited: 9 months ago Edit Post #286705 Post edited: 9 months ago Comment Post #286700 @a concerned citizen I am just trying to explain to you what is inside my head. (more) 9 months ago Edit Post #286705 Post edited: 9 months ago Edit Post #286705 Post edited: 9 months ago Edit Post #286705 Initial revision 9 months ago Question Finding voltage gain of Hartley oscillator I am trying to find the AC analysis of a BJT Hartley oscillator but I cannot continue. How do I find the voltage gain? When no feedback is there, we just find the output resistance and the current inside the output resistance and find the input resistance and the current inside the input resistance ... (more) 9 months ago Comment Post #286700 @LvW "the transfer function is defined for sinusoidal signals only!" why is that true?Why isnt the transfer function applied for a rectangular signal?Just s will be equal to something else instead of jω then. (more) 9 months ago Comment Post #286700 @a concerned citizen if s isnt any longer equal to jω maybe with the new input signal becomes 2jω the frequency at which we have a pole changes. (more) 9 months ago Comment Post #286700 For different input signals the frequency of the pole will have different values ,the pole as a pole exists for some specific values of L,C s but the frequency of the pole changes. (more) 9 months ago Edit Post #286698 Initial revision 9 months ago Question Complex frequency of a pole If we have the transfer function of a LC high pass filter:$H(s) = \frac{sL}{sL+\frac{1}{sC}}$If we want to find the pole of that filter in the end we get:$s = \frac{j}{\sqrt{LC}}$and for a sinuisodal input signal$s = j\omega$the pole exists at the resonant frequency$\omega{r}$... (more) 9 months ago Comment Post #286689 Isn't the gain inversely proportional to frequency from the rolloff frequency of a filter? Why "well past"? (more) 9 months ago Edit Post #286688 Post edited: 9 months ago Edit Post #286688 Initial revision 9 months ago Question Effect of adding stages to a filter Suppose we have a RC low pass filter of 1st order. If we add multiple stages every time we add a RC stage identical to our original does the slope of the curve in the bode plot db/Hz becomes wilder but the cutoff frequency remain the same?And is there a formula if we know the slope of the curve a... (more) 9 months ago Edit Post #286679 Post edited: 9 months ago Comment Post #286687 In reality yes, but I am assuming that the slope db/Hz is constant.It is for educational purposes only. (more) 9 months ago Comment Post #286681 Olin I said "I have to design a low-pass filter" because I never thought we would end up at this place talking about why I am building this low-pass filter,I thought you would just help me with its design if you dont like it I can edit the question. (more) 9 months ago Comment Post #286680 Is the corner frequency equal to the cutoff frequency.And yes signals with frequency > cutoff frequency will be attenuated not completely go to 0. (more) 9 months ago Edit Post #286679 Post edited: 9 months ago Edit Post #286679 Post edited: 9 months ago Edit Post #286680 Post edited: 9 months ago Edit Post #286680 Post edited: 9 months ago Comment Post #286681 I just picked the requirements in random , I dont have to design anything , I am doing it for fun but I dont know how to solve this problem. (more) 9 months ago Comment Post #286681 It isnt homework.I was just curious on the design of such a filter so here I am. (more) 9 months ago Edit Post #286680 Initial revision 9 months ago Question Cutoff frequency of single phase transmission line Signals with frequency above the cutoff frequency of a transmission line cannot be transmitted through the transmission line. But how can I calculate the cutoff frequency of a single phase transmission line? I had been reading this/02%3ATransmissionLines/2.02%3ATransmissionLineTheory) page befo... (more) 9 months ago Edit Post #286679 Post edited: 9 months ago Edit Post #286679 Initial revision 9 months ago Question How to design a low-pass filter when certain conditions must be met I am designing a low-pass filter with cut-off frequency = 100Hz and after the cutoff frequency from -3dB to -10dB the average decrease in db/Hz = -0.1 db/Hz.I know how to design a low-pass filter with cut-off frequency of 100Hz however I cannot meet the 2nd condition of the filter.How do I achieve s... (more) 9 months ago Edit Post #286537 Post edited: 10 months ago Edit Post #286537 Initial revision 10 months ago Question Find Q point in common base BJT configuration Suppose we have this graph: ![](https://electrical.codidact.com/uploads/34eS35VabSgkqjSCNoXJgMGR) How can we find the operating point (Q)?In common emitter collector we just draw a line from the vertical axis (Ic) at the point (0,VCC/RC) to the horizontal axis at the point(VCC,0) and where ... (more) 10 months ago Edit Post #286531 Initial revision 10 months ago Question Re model of transistor is the same in 2 different configuration I was studying the Re model of a transistor: ![](https://electrical.codidact.com/uploads/D4dtG1oxSCoXYxppTFLSySY9) But the Re model for 2 different configurations (common emitter and common base )turns out to be the same! I don't know why I am really confused.How is this possible? (more) 10 months ago Edit Post #286090 Initial revision about 1 year ago Question Identification of semiconducting electrical components We identify semiconducting electrical components this way: The first digit represents the number of pn junctions inside the semiconducting device The two or more digit number starting at position 3 represents the searilized identification number In the second digit I have seen only diodes wi... (more) about 1 year ago Comment Post #285683 I cant this is homework. (more) about 1 year ago Edit Post #285683 Initial revision about 1 year ago Question Choosing Y value in photoresistor graph I have designed a graph of the current in a photoresistor related to the brightness of light which hits the photoresistor. ![](https://electrical.codidact.com/uploads/iZ7zHeBq9TuyScWAkHKX283t) Our professor told us that it is more correct to draw the Current/Brightness graph than the Resistan... (more) about 1 year ago Edit Post #285325 Post edited: over 1 year ago Comment Post #285325 Star-Star and Delta-Delta topologies (more) over 1 year ago Edit Post #285325 Initial revision over 1 year ago Question Phase shift between phase and line quantities In a 3 phase Star source-Star load circuit the phase voltage has different phase than line voltage and in a 3 phase Delta source-Delta load circuit the phase current has different phase than the line current.Why? (more) over 1 year ago Comment Post #285242 Yes the question is theoretical I want to understand what bandwidth of the signal means. (more) over 1 year ago Comment Post #285242 @#53661 i don't know if it is needed thats why i am asking.I dont have a clue on what "bandwidth of the signal" means here. (more) over 1 year ago Edit Post #285242 Post edited: over 1 year ago Edit Post #285242 Post edited: over 1 year ago Edit Post #285242 Initial revision over 1 year ago Question Bandwidth of serial signal Suppose we have this stream of data.Let's assume the data stream lasts 1 sec. ![](https://electrical.codidact.com/uploads/GAKSKYDe3y6kCAeKJPr9APwc) How do we find the bandwidth of the data?Do we Fourier transform the signal in order to find its components in the frequency domain? Assume ... (more) over 1 year ago Comment Post #285171 Where should I ask it then? (more) over 1 year ago Edit Post #285170 Initial revision over 1 year ago Answer A: How can we grow this community? 1)When you search on Google about a specific electronics/electrical engineering question Codidact is not in the first choices so I think users should try to upload relevant content frequently and self-answering the question. 2)In chemistry.stackexchange.com you can ask a question and even answer q... (more) over 1 year ago Edit Post #285168 Initial revision over 1 year ago Answer A: How to treat data communication questions? I may be a little bit biased on this one because it was my question which started this thread but : I don't think data communication question should be generally off-topic because it evolves binary logic and the way the data are sent/received is through electric signals. (more) over 1 year ago Edit Post #285155 Initial revision over 1 year ago Question Splitting of message inside the layers Assume a app generates a message (stack on computer).Each layer of the sending entity will put then control information in the data depending on the protocol and transmit the data to the next lower layer . ![](https://electrical.codidact.com/uploads/9VT3qobzToaebSDMYBQ3PR9c) Each layer of the ... (more) over 1 year ago Edit Post #284982 Initial revision over 1 year ago Question Asynchronous connection question Assume we have a channel and send 7-bit data(0100100) asynchronously with 1 parity bit(0).Suppose the start bit is 1.The end bits are in the same logic level with the idle state of the channel(0).How does the receiver understand the end bits?In my case the last 2 0s could have been the end bits but i... (more) over 1 year ago Edit Post #284865 Initial revision over 1 year ago Question What is minimum resolution here? In this datasheet it says that the minimum resolution is 0.1uA for the 10mA range.What is this minimum resolution?Is it the sensitivity of the multimeter for the 10mA range? (more) over 1 year ago Comment Post #284818 I didnt go to university today and we had lab hours.In the laboratory we use a Protek IDM 505 and I didnt measure some circuits which are for homework so I am searching it online to see if I can find anything. (more) over 1 year ago Edit Post #284818 Initial revision over 1 year ago Question Resistance of digital ampmeter Can we find the internal resistance of a multimeter ,when we use the multimeter like a ampmeter, from its datasheet? I am trying to find the internal resistance of IDM 505 and I went to the datasheet to the current section and the most relevant thing I could find was the accuracy but as far as I k... (more) over 1 year ago Comment Post #284253 Yes i am interested in the capacitance between the windings.How can we make it bigger? (more) over 1 year ago Edit Post #284562 Initial revision over 1 year ago Question Capacitors of voltage regulators Assuming we have a voltage regulator : ![](https://electrical.codidact.com/uploads/qvcwiw5cLSoLWSigewwvvezS) Why do we have to ground Vin and Vout using 2 capacitors just like that?Co could be to provide a low resistance path to GND at high frequencies but what is the role of Ci? (more) over 1 year ago Edit Post #284545 Initial revision over 1 year ago Question Confusion with Wikipedia article on multivibrator circuit A while ago I made a question about the monostable multivibrator .Lets get a picture of it: ![](https://electrical.codidact.com/uploads/v4DMcGETqrfhmKpAaqYjEoPx) When switch is closed it enters its unstable state and it eventually returns to the stable state However Wikipedia states that thi... (more) over 1 year ago Edit Post #284514 Post edited: over 1 year ago Edit Post #284514 Post edited: over 1 year ago Edit Post #284514 Post edited: over 1 year ago Comment Post #284514 I will put some labels (more) over 1 year ago Edit Post #284514 Initial revision over 1 year ago Question Find feedback of circuit I have this circuit: ![](https://electrical.codidact.com/uploads/nk1CTmvqhfvpNqhUvgbaea2x) I think that R3 acts like a feedback path from the output to the input.However I am not sure what will happen if I change the value from 100Ohms to lets say 1kOhms. I have this image in mind: ![](ht... (more) over 1 year ago Comment Post #283942 "...how to make it because there are not genuine current sources in nature...".I disagree . A photodiode is a current source in photovoltaic mode. (more) over 1 year ago Edit Post #284253 Post edited: over 1 year ago Edit Post #284253 Initial revision over 1 year ago Question Capacitance gain using conductive core for inductors I have learnt that if we have 2 parallel conductive plates and we seperate them the capacitance is increased if we put a good conductor between the plates. Now the resonant frequency of a inductor(1mH) is about 100kHz which doesnt make it practical for application when the desired output frequency... (more) over 1 year ago Edit Post #284219 Post edited: over 1 year ago Comment Post #284219 @Olin Done!It has been fixed (more) over 1 year ago Edit Post #284219 Post edited: over 1 year ago Comment Post #284219 @Olin i dont think it is possible in Multisim NOT to make any zig-zag . (more) over 1 year ago Edit Post #284219 Initial revision over 1 year ago Question Change of pins in monostable multivibrator In monostable multivibrators we use a trigger signal applied to the base of the transistor which is usually off to enter the astable region ![](https://electrical.codidact.com/uploads/UTmX2yRXNrZ9cnWP5aWWYi4J) Can we instead have a pin which is connected directly to the base of Q1 and when that... (more) over 1 year ago Edit Post #284207 Initial revision over 1 year ago Question Electrolytic vs ceramic capacitors about self-resonance frequency Which capacitors have smaller self resonance frequency?I would bet my money on electrolytic capacitors because they are usually much bigger than the ceramic capacitors however I don't know if they self inductance changes as well so here we are asking this (more) over 1 year ago Edit Post #284196 Initial revision over 1 year ago Question Capacitance of inductor What is a typical value for capacitance of a real inductor? Does this internal capacitance exist only under AC and not DC? (more) over 1 year ago Comment Post #284076 @Carl please clarify?Isnt it well written,correct or well presented? (more) over 1 year ago Comment Post #284076 Because it is useful if someone wants to ask something relevant to the question. (more) over 1 year ago Edit Post #284076 Post edited: over 1 year ago Edit Post #284074 Post edited: over 1 year ago Edit Post #284074 Post edited: over 1 year ago Comment Post #284074 Yes oops I will edit the image. (more) over 1 year ago Edit Post #284074 Post edited: over 1 year ago Edit Post #284017 Post edited: over 1 year ago Edit Post #284076 Post edited: over 1 year ago Edit Post #284074 Post edited: over 1 year ago Edit Post #284018 Post edited: over 1 year ago Edit Post #284076 Initial revision over 1 year ago Answer A: Parallel RLC circuit It all depends on the values of the components:If ![](https://electrical.codidact.com/uploads/i8DAX2tLRnQV7eBAtFq2icWe) the system will very slowly decay until the energy of the system reaches 0. If ![](https://electrical.codidact.com/uploads/B6ExJnRcfsKJ7YkuCPD3pLqT) the system underg... (more) over 1 year ago Edit Post #284074 Initial revision over 1 year ago Question Parallel RLC circuit How to find the equation of voltage of the top common node of R1,L1 and C1 after the switch is moved? ![](https://electrical.codidact.com/uploads/TevMpbc9kY6tse4mnkjBN8Cp) (more) over 1 year ago Comment Post #284018 They are not homework questions and I make the images on my own , it takes plenty of time in order to contribute to this site so please respect that. (more) over 1 year ago Edit Post #284021 Initial revision over 1 year ago Question Inductance vs frequency Suppose we have a sine signal applied to a inductive load. Is the inductance of the load changed if the frequency of the signal is changed? (more) over 1 year ago Edit Post #284018 Post edited: over 1 year ago Edit Post #284017 Post edited: over 1 year ago Edit Post #284017 Post edited: over 1 year ago Edit Post #284018 Initial revision over 1 year ago Answer A: Series RLC circuit It all depends on the values of the components:If ![](https://electrical.codidact.com/uploads/8ym42jU8HUER4jr6uEFSL2QW) the system will very slowly decay until the energy of the system reaches 0. If ![](https://electrical.codidact.com/uploads/mL9YkvUSVf8BH1MW96VuTu2V) the system und... (more) over 1 year ago Edit Post #284017 Initial revision over 1 year ago Question Series RLC circuit How to find the equation of current of the RLC circuit after the switch is moved? ![](https://electrical.codidact.com/uploads/87iESoUu42B4bQo2FKTogWHp) (more) over 1 year ago Comment Post #283960 @Andy aka if you read the answer a little bit below that statement (which is true) i say we have voltages due to mutual inductance-> we can say that a current exitting the doted end of the inductor can be translated to a voltage drop from the dotted end to the undotted end. (more) over 1 year ago Edit Post #283958 Post edited: over 1 year ago Comment Post #283958 I mean how inductive coupling changes the total series inductance. (more) over 1 year ago Edit Post #283958 Post edited: over 1 year ago Edit Post #283960 Post edited: over 1 year ago Edit Post #283960 Post edited: over 1 year ago Edit Post #283958 Post edited: over 1 year ago Edit Post #283960 Initial revision over 1 year ago Answer A: Coupling of inductors When 2 inductors share the same magnetic field they become coupled and besides their self inductance they have a mutual inductance as well. For this circuit: ![](https://electrical.codidact.com/uploads/9BbSeaQgDrCoxDMhzybYnxP9) Now current entering one coil marked with a dot, produces a ... (more) over 1 year ago Edit Post #283958 Initial revision over 1 year ago Question Coupling of inductors Which will be the total series inductance? ![](https://electrical.codidact.com/uploads/ChgYqAphvBFCAyPoFG2m4tAM) (more) over 1 year ago Comment Post #283956 It isn't dimensionless im just doing the math. (more) over 1 year ago Comment Post #283956 I am using a LateX editor so I cant do what you want. (more) over 1 year ago Comment Post #283956 The (missing)units are obvious if you read the post. (more) over 1 year ago Comment Post #283956 I dont see any errors maybe you can enlighten me (more) over 1 year ago Edit Post #283927 Post edited: over 1 year ago Edit Post #283956 Initial revision over 1 year ago Answer A: Voltage and Current of capacitor After the switch is closed: hi The general formula for finding the voltage of the capacitor is: hi where Vf is the voltage of the inductor after infinite time,Vo is the voltage of the capacitor at the time the switch is closed Because capacitors resist any change in voltage hi ... (more) over 1 year ago Edit Post #283955 Initial revision over 1 year ago Question Voltage and Current of capacitor How do I find the voltage of the capacitor and the current through the capacitor after the switch is closed? (more) over 1 year ago Comment Post #283926 The circuit isnt wrong but what you have suggested is a improvement of the current source/switch relationship. (more) over 1 year ago Comment Post #283936 1) The current source provides 0.1A to the circuit but this could well have been a typo or you may have not seen it well which is partly my fault because I didnt write it brightly enough 2)the time costant is L1/R so the t/T must have units of Ohms*seconds/Henries (more) over 1 year ago Comment Post #283936 Olin maybe you may want to delete this post. (more) over 1 year ago Comment Post #283926 What do you mean by designators exactly!? (more) over 1 year ago Edit Post #283927 Post edited: over 1 year ago Edit Post #283927 Initial revision over 1 year ago Answer A: Current and voltage of inductor After the switch is closed : hi The general formula for finding the current through the inductor is this: hi where If is the current through the inductor after infinite time,Io is the current of the inductor at the time the switch is closed. Because inductors resist any change in curre... (more) over 1 year ago Edit Post #283926 Initial revision over 1 year ago Question Current and voltage of inductor How do I find the current through the inductor and the voltage of the inductor after the switch is closed? (more) over 1 year ago Comment Post #283904 Done check it out now. (more) over 1 year ago Edit Post #283904 Post edited: over 1 year ago Comment Post #283904 You are correct I will edit (more) over 1 year ago Edit Post #283904 Post edited: over 1 year ago Edit Post #283904 Post edited: over 1 year ago Edit Post #283904 Initial revision over 1 year ago Answer A: Select resistor for a diode A diode obeys the Shockley diode equation and for this circuit we have:hi hi The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed: For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V... (more) over 1 year ago Edit Post #283903 Initial revision over 1 year ago Question Select resistor for a diode Suppose we have this circuit see me How do I pick a appropriate value for the resistor R1? (more) over 1 year ago Edit Post #283896 Post edited: over 1 year ago Edit Post #283896 Initial revision over 1 year ago Question Diode like a frequency mixer Based on this paper on Wiki a diode can be described as a frequency mixer due to the exponential relationship between current and voltage.What I don't get from which point to which point do we measure the voltage with the different frequency(or whatever)? So if we connect a oscilloscope to the cir... (more) over 1 year ago Edit Post #283585 Initial revision over 1 year ago Question$Q$and$\overline{Q}$in bistable multivibrator In this bistable multivibrator which is$Q$and which is$\overline{Q}$? (more) over 1 year ago Comment Post #283436 Suppose we have a transistor connected in series with a magnetic tunnel junction.1st case:the output voltage is low(the transistor is off) (0V)this represents the case of no charge state.2nd case:the transistor is on and the 2 layers of ferromagnetic materials which create the magnetic junction, hav... (more) over 1 year ago Edit Post #283436 Post edited: over 1 year ago Comment Post #283436 @#53072iot if the charge state is 0, then we dont hav to worry about the spin state.Spintronics provide us with 3 available states unlike electronics which provides us with only 2 states. (more) over 1 year ago Edit Post #283436 Initial revision over 1 year ago Answer A: A signal with one mode or with three or more modes > The term "Discrete" uses to describe a signal with two modes. Wrong. Discrete means it can only take some values , not all values. I suspect by 'modes' you mean # of possible outputs. If we have a system which outputs only have 1 possible output then what would be the point of that system?... (more) over 1 year ago Edit Post #283369 Initial revision over 1 year ago Question Tunnel current equation The current through the tunnel diode is: hi where$I{f}$is the current from the Shockley diode equation and$I{tunnel}is the tunnel current. Is there an expression for the tunnel current or is it found 'experimentally'?[]() (more) over 1 year ago Comment Post #283331 So a DC blocking capacitor to not allow any current flowing from the DC source to the AC source? (more) over 1 year ago Edit Post #283325 Initial revision over 1 year ago Question Adding resistance to varactor circuit If we a varactor and we want to control let's say the resonant frequency of the circuit ,in my schematic we must add R1 correct?Else we create a low resistance path for current to flow not through the varactor so the "AC circuit" gets distorted from the "DC circuit". hi So by changing the val... (more) over 1 year ago Edit Post #283249 Initial revision over 1 year ago Answer A: 3+3 doesn’t show 6 The correct 1 bit full adder is this:hi (more) over 1 year ago Edit Post #283244 Initial revision over 1 year ago Question 3+3 doesn’t show 6 I have a problem which I don’t understand how to solve. I have this 2-bit adder, but when I select A1AO to be (11)2 3 and B1BO to be (11)2 3 and run it on Logisim it doesn’t show me 6. Instead it shows me 4. How can I fix it? hi (more) over 1 year ago Comment Post #283207 I know that.Is there a way to use the comparator(s) as 'effeciently' as possible(no loops,storage of value ) and make a simple logic digital circuit? (more) over 1 year ago Edit Post #283206 Initial revision over 1 year ago Question Division of binary numbers logic circuit If we want to divide two numbers I have problem implementing this logic.I am posting 1 images with 2 different steps to the solution. In example a) the most significant digits of the divident >= divisor we subtract the divisor from those 2 digits. hello In b)the most significant digits of th... (more) over 1 year ago Comment Post #283172 I cant understand which pins to connect with which pins. (more) over 1 year ago Comment Post #283170 I think multiplication can be done without bit shifting just by using full adders and taking advantage of the vertical addition of 2 binary numbers.However we are missing the point here.Is there a similar 'function' which does the same for vertical subtraction? (more) over 1 year ago Comment Post #283170 I have heard that for division of binary numbers you need to understand well subtraction so just like we can multiply 2 numbers with full adders maybe we can divide 2 numbers with full subtractors thats why I want to know how to edo subtraction using full subtractors. (more) over 1 year ago Comment Post #283172 I know how to make a full subtractor i just dont know how to connect multiple of them in order to make subtraction of 2 binary numbers with more than 1 bit (more) over 1 year ago Edit Post #283170 Initial revision over 1 year ago Question 2 bit subtractor using full subtractor Can we make a n-bit subtractor using full subtractors or if we want do subtract one binary from another we must use full adders and use the complement of the 2nd number to do the subtraction? I have only found examples which we use the complement of the second number and using full adders if it is... (more) over 1 year ago Edit Post #282738 Initial revision over 1 year ago Question Electric circuit with antenna Moderator's note: This is getting ridiculous. You keep posting these drawings that are barely legible. The scribbling is bad enough, but the uncropped images are unacceptable. The image you originally posted below was 2500 x 1667 pixels, even though the drawing occupied only a small piece of th... (more) over 1 year ago Edit Post #282733 Initial revision over 1 year ago Question JFET equation of current Is this equation valid only when a JFET in saturation mode , correct? because in the ohmic region the JFET acts like a voltage controlled resistor and increase in VDS increases the resistance of the JFET. Hi (more) over 1 year ago Edit Post #282711 Post edited: over 1 year ago Edit Post #282711 Initial revision over 1 year ago Question Diodes used in mixers Suppose we have this circuit which is supposed to be an unbalanced frequency mixer. But how does the diode generate a signal with new frequencies at the output? Hi (more) over 1 year ago Comment Post #282710 An input signal can have noise and usually the noise is an AC signal so if im receiving dc signal+noise i would like to remove the noise. (more) over 1 year ago Edit Post #282709 Initial revision over 1 year ago Question Extract DC component of mixed signal How can we extract a DC signal from a mixed signal?If we want to extract the AC component of a signal we can use a blocking capacitor to remove any DC offset but how do we achieve the opposite?Can we use a band-pass filter? (more) over 1 year ago Edit Post #282690 Post edited: over 1 year ago Edit Post #282690 Post edited: over 1 year ago Edit Post #282690 Initial revision over 1 year ago Question MOSFET differential to single ended converter intuition How does the differential to single ended converter work? In order for the circuit to work, Q1 and Q3 must be in the saturation region and depending on the voltage inputs, one of Q2 and Q4 will be in the ohmic region and one will be in the saturation region. I understand that IQ1 is copied to (... (more) over 1 year ago Comment Post #282672 Yeah for you it may be easy I have tried learning MathJax and couldn't (more) over 1 year ago Edit Post #282671 Post edited: over 1 year ago Comment Post #282672 @#36396 I dont know how to use LaTeX and I used one of the online editors I found.I tried to find an online editor which didnt do that but I couldnt find one. (more) over 1 year ago Edit Post #282671 Initial revision over 1 year ago Question Voltage of tank circuit is invalid In a previous question we found that for a critically damped oscillation: $$I(t) = 2 t e^{-0.5 t}$$ But if we integrate to find the voltage through the capacitor: $$V{CO} + \frac{1}{C} \cdot \int0^t{I(t)}dt$$ the integral is always a positive value which doesn't make any sens... (more) over 1 year ago Comment Post #282635 Thanks I understand now/ (more) over 1 year ago Comment Post #282635 Sorry what you write doesnt make any sense to me.From KVL Vs=Vc+Vl+IR , I=0 and Vs=0 (no battery connected to the circuit)->VC=-VL->VL=-2V. (more) over 1 year ago Comment Post #282635 I still dont get it VL=-VC = -2V. (more) over 1 year ago Comment Post #282627 But the opamp can correctly function without the capacitor,correct? (more) over 1 year ago Edit Post #282624 Initial revision over 1 year ago Question Capacitor in 2nd stage of opamp Inside a op-amp after the stage where the differential signal is converted to single ended , there is further amplification of the DC signal.For AC signals there is a capacitor parallel to the transistor.Why is it there? (more) over 1 year ago Comment Post #282585 Ok it is ready for reopening (more) over 1 year ago Edit Post #282585 Post edited: over 1 year ago Edit Post #282585 Post edited: over 1 year ago Edit Post #282585 Initial revision over 1 year ago Question Critically damped oscillation issue I have a question about this circuit:(critically damped oscillation) SeeMe For a critically damped oscillation for a series RLC circuit the equation of current has this form I(t)=D1te^(-at)+D2e^(-at) where D2 =I(0+) and D1-aD2 = dI(0+)/dt=VL/L. Due to L1 :I(0)=I(0+)=0A and by applying KV... (more) over 1 year ago Comment Post #282434 How are the equations derived?I didnt get it. (more) almost 2 years ago Comment Post #282363 Yes and Vout cant become less than Vin-.How can we fix this? (more) almost 2 years ago Comment Post #282363 Excellent answer!But I have done some experiments on falstad and every time Vin+ becomes less than Vin- Q2 is driven to saturation and if Vin+ becomes more than Vin- Q4 is driven to saturation.Is that normal? (more) almost 2 years ago Edit Post #282361 Initial revision almost 2 years ago Question Help with differential to single ended voltage converter Hello I don't understand how this differential to single-ended voltage converter can work. What I don't understand is why we place a current mirror(a current mirror copies the current flowing through one transistor to another transistor) and how is the output voltage affected by the input volt... (more) almost 2 years ago Edit Post #282262 Initial revision almost 2 years ago Question Unexpected phase shift in results I find the current flowing through the capacitor \begin{align} I{C1}(t)&=\dfrac{\mathrm{d}}{\mathrm{d}t}\left[V1(t)-I{C1}(t)R1\right] \\\\ {}&= \dfrac{\mathrm{d}}{\mathrm{d}t}\left[\sin(t)-I{C1}(t)\right] \end{align} and by solving this differential equation we get\$I{C1}(t) = \dfrac...
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almost 2 years ago
Edit Post #282180 Initial revision almost 2 years ago
Question Current and voltage in AC circuits without impedance
How can we find the equation of current and voltage of a capacitor circuit if the input voltage is AC without using the impedance formula Xc = -jωC?. SeeMe We have for homework to find the equation of current of the circuit and the equation of voltage of the capacitor assuming we just connected...
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almost 2 years ago