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  1. Boltzman Oscillation

    The important non-fundamental electrical components?

    Through my 2 analog classes and 2 electronics classes I have learned about resistors, inductors, capacitors, BJTs, Mosfets, and FETS. What are some other fundamental components that I should be taking a look at? To add to this, I dont consider gates as fundamental because they are built up from...
  2. J

    Engineering Sketching output waveforms while considering slew rate

    1. Using the frequency equation I know the time period is 1 millisecond. 2. The duty cycle (50%) equation tells me that the pulse width and the amplitude is 1 V. 3. Thus the input waveform looks like this : (?) 4. As the slew rate is 0.5 volts per microsecond, the output voltage would take...
  3. J

    Engineering Basic opamp design problem ##V_{output} = 3V_1 - 2V_2##

    Here I let ##R_2 = 2 ## kohms and ##R_1 = 1## kohms. Using this suggests that ##R_3 = 0## and ## R_4 = 1 ## kohms (?!) The resulting circuit is Is this the correct way to solve this? PS : I just realised that I have interchanged ##V_1## and ## V_2## in the diagram!
  4. Boltzman Oscillation

    Are ISFETS available for cheap or am I out of luck

    I was looking into measuring the ph levels of a lake nearby where I live. I wanted to tie the experiment to my electronics coursework so I did some reasearch and found the wonder electronic that is the ISFET. Unfortunately, I cannot find anywhere to buy an ISFET transistor; I can easily find...
  5. H

    Designing a motor control circuit to use a DC Motor to behave as torsional spring

    I'm a relatively new entry into the world of electronics so my understanding of what is possible may not be an accurate one. In a nutshell, I would like to have a DC motor act as a torsional spring with some variable virtual spring constant (k). The motor, or "spring", would act against an...
  6. therealist

    How do I find the frequency, speed and direction of a wave

    Hey I am trying to learn how waves move in time and I am not sure how to solve the following question. Can someone please guide me through it.
  7. M

    How to calculate the efficiency of a switch mode power supply?

    I know how to calculate the power output and input by analyzing the current in put and output with multimeters and using the formula P=VI. But P_out is obviously incomparably smaller than P_in so the efficiency would suck this way. Is there a better way to do this??
  8. Boltzman Oscillation

    Engineering Help finding this node voltage

    I am given that all the BJTs are the same. First of all, when finding node voltages like Vref should I make the node voltage a voltage source first and then do circuit analysis? If so then I would use KVL but that does not give me Vref = 2Vbe. I do know that Vref = Vb1 = Vb2. What am I doing...
  9. Boltzman Oscillation

    Must a load consume the entire available current or only what it needs

    So if I have a source of 5V and 20 amp then the maximum power I can get from the source will be: $$ P_{max} = 5*20 = 100W$$ but my load can only take in 5 watts, it will blow up. But, does this have to happen or does my load only take what current it needs? My guess is that the load takes in...
  10. AlphaLibrae

    Find the Thevenin's Equivalent for the following circuits

    I have actually already written out and solved for my own solutions to these problems, but I was wondering if I could get a second opinion on my solutions: For Problem 3: For Problem 4:
  11. Boltzman Oscillation

    How can I determine whether my basic circuit will work? A battery and two light sources...

    Homework Statement:: How can I determine whether my basic circuit will work? A battery and two light sources. Homework Equations:: conceptual question, use basic ohms law, current law, voltage law, etc. This is not a homework question, i am just trying to understand electronics better. I am...
  12. W

    How to find the current and voltage in a circuit with current sources?

    Summary: Facing a circuit with 2 parallel resistors and 2 current sources (1 dependent, 1 independent). Trying to find the current, voltage, power delivered by the independent current source and power delivered by the dependent current source. I'm trying to start by finding the current i0 but...
  13. C

    I How do I calculate the expected Gain?

    I am doing an experiment in electronics with AC RLC circuits, But there are a few things about what I need to do that I don't understand. First: While I know in the circuit diagram we include the internal resistance of the Inductor in series, but I don't know why we include it in series rather...
  14. J

    Engineering Calculating the gap of a parallel plate capacitor

    I've been given this question for my TMA2, I've tried looking at the learning material but it gives no information on how to calculate the gap? Does anyone have a formula for this? Or can someone point me in the right direction? Thanks
  15. M

    PNP transistor and Voltage

    The problem: My attempt:
  16. D

    The 555 timers I use don't always generate pulses

    I have 3 555 timers. They don't always produce pulse. Sometimes They do. Sometimes they don't. Why don't they always produce pulses? I use electrolytic capacitors. There is nothing connected to the 5th pin.
  17. astroman707

    Studying What's the best way to apply the concepts learned in physics 2?

    I'm finishing up physics 2(intro E&M) at my college, and I'd like to apply the concepts I learned in it over the summer. I was considering working through an electronics book, or building a radio, etc. What kind of projects or books do you recommend to cement some of the topics I learned in a...
  18. MarcusAu314

    Electrical How can I waterproof an electrical component?

    Good evening, it's been a while since my last thread here in PF. I will go straight to the point: I want to measure temperature using an NTC3950 thermistor. My circuit diagram is as follows: It's basically a voltage divider. By varying the temperature acting upon the thermistor the output...
  19. iVenky

    I Why high Q factors have low phase noise

    If we define Q factor as 2*pi* energy stored/ energy dissipated per cycle, what's the physical insight behind obtaining low phase noise for oscillators when we have high Q factors? (I know the mathematical derivation based on finding the frequency profile of an oscillator (like LC oscillator)...
  20. A

    B The Gain of the Inverting Amplifier and Virtual Earth...

    This is an inverting amplifier incorporating an ideal op-amp with infinite open loop gain. I have a simple question concerning the derivation of its gain (-R2/R1). The point I circled is at 0V (Virtual Earth) but then, if V+=V-, Shouldn't Vout=0 regardless of what R2 and R1 are?? What's wrong in...
  21. Baibhab Bose

    A Temperature of a thin bulb filament

    In my assignment question, the length L and radius r is given and asked to find out how the Temperature of a thin bulb filament which depends on those two parameters. and the answer is r^(1/4)*L^(-1/2). I cant figure out how. Which relation is involved?
  22. Muhammad Usman

    How is the Aging of Electronic Equipment determined?

    I am working in telecom company and they told me that they installed new system and then they told me the equipment will be EOS (End of Service) after 5 years. I was wondering that how the electronics equipment's age is calculated. If I strictly categorize my questions and explain the confusion...
  23. R

    Equivalent resistance with a capacitor

    Homework Statement So I need to find the equivalent resistance for the following RC circuit to calculate the time constant, but I got stuck in terms of finding out the equivalent resistance. Homework Equations V = IR The Attempt at a Solution So the thing im not sure on is how do you...
  24. akaliuseheal

    Reading datasheets to pick a comparator

    Hello, I've got a voltage comparator, well only on schematics, I need to chose one and I need some help interpreting datasheet. The datasheet I was looking at is of a lm393. My input voltage ranges from -7.8V to +7.8V. The datasheet says -0.3 to something. So it's not usable, right? I was also...
  25. akaliuseheal

    Hysteresis of a voltage comparator

    Hello, I am designing a circuit which basically takes two voltages (V1,V2) and based upon which one of the two is greater, turns corresponding LED. So, I have got to the part where I have output from differential op amp that is the input of the inverting voltage comparator with hysteresis...
  26. R

    What's the advantage of using a voltage buffer amplifier?

    i want to understand whats the advantage of using a voltage follower
  27. S

    Want to build a simple audio filter

    Hi, I have an old system that outputs a stereo audio signal (using Left and Right RCA audio cables). However for some reason this system is also outputting a high-frequency noise on both channels regardless of its operation. At this point I think it would be simpler to build a simple audio...
  28. akaliuseheal

    Use of 4 floating current sources

    Homework Statement I have 4 resistive sensors thus I need to tie 4 floating current sources. Floating current source will give me output voltage linear to the resistance of a sensor. I know it is not the best solution but it is good enough. Image provided: Homework Equations None The...
  29. F

    Need Forum for Outlandish Science Ideas

    Hello, Does anyone know of a science forum that deals with far out, controversial theories & ideas? This would be similar to the science fiction forum here at PF but may even be more outlandish, however postings would receive serious consideration. I have made some simple animations that I...
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