Can somebody help how message signal (words spoken near microphone) is modulated using LC circuit and how lc circuit oscillates at particular frequency by applying dc voltage. In the below circuit l1 is 0.1 uH and capacitor is vc10-100 pf.  Actually in frequency modulation increase in voltage of message signal increases the frequency of carrier frequency and decrease in the voltage of message signal decreases the carrier frequency .I want that concept to be linked to the circuit. Thanks in Advance
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&ndash; Schematic created using   This is a minimalist FM transmitter I've found from   I'm a bit confuse about three things  1)How does this modulates the base input signal to frequency modulation ?  Because I don't see any change happening neither in Inductance nor in Capacitance of that LC tank oscillator. Is that because of C1 somehow ?  2) For what purpose capacitor C5 is used ?
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I was reading some articles about digital and analog modulating processes. One of them was this:  At a certain point is says:  The bandwidth produced is a function of the highest modulating frequency including harmonics and the modulation index, which is: m = Δf(T) Δf is the frequency deviation or shift between the mark and space frequencies, or: Δf = fs – fm T is the bit time interval of the data or the reciprocal of the data rate (1/bit/s).  I'm a bit confused with these terms. How exaclty the bandwidth relates do data rate? Let's take this image by example:  From what I've understood, if I want to modulate a digital signal by FSK process, I should just choose 2 different frequencies to represent 0 and 1. I should also choose two frequencies that are harmonics of a fundamental frequency to get &quot;smooth&quot; transitions (zero cross), is that correct? Besides that, how my data rate is related to this bandwidth? Isn't bandwidth the width of a channel? Let's say I'm using a 2.4GHz transmission with a channel that goes from 2.4GHz until 2.450GHz, then I will have a channel of 50MHz, correct? My bandwidth in this case isn't 50MHz? If so, my bandwidth should only be expressed by Δf, no? In other words, since I only need 2 differente frequencies, my channel width would be only the difference between those frequencies. With that said, I cannot see where data rates comes in. I think the only thing that would influence on that rate would be how long each bit is holded. As I said I'm confused with these conecpts. So if someone please could clarify my ideas.
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I'm a newbie in electronics and Trying to understand and build this circuit. would somebody tell me the rule of R1 &amp; C2 in this circuit and their magnitude effect on the controlling of process.why didnt feedback start just after the output of opamp?How could i find the transfer function between the voltage output of Hall effect sensor and the voltage output of MOSFET drain?  The schematic is the circuit of a magnetic levitating tool at:    Thanks so much
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I am working on the lab which is allowed to ask other people for hints.    In the image, program called "Audacity" is used to capture that waveform.  Question 1     In the image it says, "The peak-to-peak span of the signal is about 2.0 V"   It says its span range is 2.0 V, but I think that it spans from around -0.2 (lowest point in the wavefore picture) to +0.8 (highest point in the wavefore picture) according to picture. But why this description says it is 2.0 V?  Question 2     In the image it says, "the graph below can show a range of about 4 volts top-to-bottom"   Similarly, I think total range of top-to-bottom in the image is from -1.0 to +1.0, which I think 2V in total. But why this description says it is 4 volts?
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I have been looking the number of methods to measure inductance of a coil if you don't have an LCR meter available, and I have had some difficulty. I designed and built a coil and I would like to confirm its inductance, which theoretically is ~\$2\mu\mathrm{H}\$.  One method is putting a resistor in series with the inductor and applying a signal. I've seen two things in regards to this one is to adjust the input frequency so that the voltage across the resistor is half the input and then work out \$L\$ using         &ndash; Schematic created using  $$ L = \frac{R}{2\pi f\sqrt{3}} $$ And the other is to instead adjust the input frequency until the signals are \$-45^\circ\$ (degrees) out of phase and then work out \$L\$ using $$ L = \frac{R}{2\pi f} $$ I've tried both these on a inductor of known value and I do not get close to the expected value. So I figure I am doing something wrong, but I am not sure what as it is a pretty simple setup. More importantly, I do not fully understand the formulas used and how one gets to these to work out the inductance.  The known inductor is \$\sim 1.5 \mu\mathrm{H}\$ (tolerance 20%) and the resistor I used was \$6.75 \mathrm{k}\Omega\$. So I also wonder if perhaps the inductor value is too low for this type of setup for measurement as I have typically seen \$\mathrm{mH}\$ in the results of the examples I have seen? Or if I choose an inappropriately valued resistor?  I then tried the LC trap, with \$10 \mathrm{nF}\$ capacitor and my inductor, and that worked for me. Pulsing the input signal and then looking at ripple frequency.  $$ f = {1\over 2\pi\sqrt{LC}} $$ At least it appears to have as I was able to work out the inductance of the known inductor to within its tolerance. And got near to what I expected with my built coil.          Mostly I am curious about the first methods using the series resistor, as this is one of the first things that comes up when looking at how to measure inductance, And I would like to understand this better and get it to work for me if possible.
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So I found this 9V 1A AC power supply laying around and decided to make a DC source.  I rectified and added a capacitor to make things a bit even. After adding a capacitor my voltage boosted from 9V to 14V. Can somebody explain why this happened for me? (maybe this has something to do with frequency?) According to theoretical graph I should get aprox the same voltage even after adding the capacitor. And voltage varies depending on how much capacity the capacitor has (aprox. from 12-16V). Maybe there's some sort of equation to determine the actual output voltage depending on caps? It would be great to get 12V out of this thing.   P.S.: Personally I find this boost weird because this circuit doesn't have any switches and coils to boost the voltage, so I need an explanation, thank you in advance!
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I would like to know how to understand/analyse the circuit below. And sorry but my level in electronics is not that high and I could only tell that the opposing transistors on the left are meant to cancel any current from the input , yet I don't really understand the B stage which I think the C stage is well related to , and if I wanted to analyse the nodes around the circuit apart from (A,B,C) How can I do it ?  Is it by measuring the current on resistors/nodes?  and note that the output voltage of the circuit in node C is zero this is what it meant to be.I would appreciate any help.  Regards
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this time I'd like to ask a few questions about capacitors, all noob questions again;   What's a better idea, having one capacitor at 5x farads or five capacitors at x farads each? I want to get a certain amount of voltage and want to discharge the direct current as fast as possible. I'm trying to build an amateur railgun, and intend to shoot projectiles that weigh about 10 grams. Using the formula that someone helped me with in my other question, in order to give that a speed of 100m/s at a total of 20.000 uF assuming 2% efficiency I'd need a little less than 112V's. The question is, is this amount of voltage I need my capacitor or series of capacitors to provide for the duration of the shooting? What determines how much voltage a capacitor can hold? This may come off stupid as I am aware that there is a voltage rating when you buy them, but better safe than sorry. I was only assuming 2% efficiency, and depending on my rail length it could be higher. The question is, what determines how fast the capacitor will discharge and how it can be prevented from going above the rated voltage?
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I'm just a dabbler in electronic circuits and I'm really still kind of a noob. I am working on a project called the "Atari Punk Console" (Originally known as the "Stepped Tone Generator") but there are some parts of the wiring schematic that I don't understand, specifically the parts with the ground symbol.  Here is the schematic:   See those two ground symbols? I don't understand how to properly connect the circuit to ground at these points. How can I do this and be sure that I did it properly. I don't understand grounding at all so any pointers or clarification is also welcome. Thanks in advance.
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All the develooment boards I have seen yet with serial communication support usually have MAX232 line trasceiver. However, I have come across this Olimex PIC-LCD development board that does not have it. Rather, it seems to use discrete components to achieve the same aim. Below is the schematic. The RXD and TXD are connected to the PIC:    I am trying to understand how this works. For recieved data we would need to clamp the voltage to Vcc. For transmitted data we need to amplify the signal. I vaguely understand that there would be a simple clamp diode for the received data and a charge pump made up of capacitor and diode for the transmitter. The transistors are resistors are confusing me. What purpose do they serve?
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Could someone please explain the role of the transistor in this circuit? I have a feeling it has to do with the LC circuit but I'm not sure and don't understand completely. The following is an image of the circuit (the transistor is n-type. It is used in lots of sensors to detect and generate ultrasonic waves.
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I'm currently encountering a problem when using a relay switch with a 5v receiver. When using the same receiver with a row of LEDS it works flawlessly. I've noticed that the relay keeps making the switching noise over and over like I'm pressing the transmitter really fast apart from the fact I'm not. Also, when the transmitter is moved closer to the receiver from 20" to around 1" the problem stops. Below is some circuits to help show you my setup.  Any help appreciated thanks.  Setup Specs   USB 5v DC (2AMPS) Receiver (XY-DJM-5V - SC2272-M4) Relay (SRD-05VDC-SL-C 5V DC) Transmitter (XY-04) Diode (1N4001) Transistor (2N2222A) Resistor (1.8K Ohms)          &ndash; Schematic created using   Antenna Signal Workaround or Booster  I believe this issue is related to wireless signal on D0. Basically above 20" inches the output to the relay drops from 5.05v to 0.5v and is obviously causing the problem. I think I need to boost the signal or replace the transistor with something that triggers at low and high current but have no clue. Any help appreciated, I'm new at this.  Board Setup
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I just want to know how do I connect the ground in the circuit. I know how to connect DC source but I'm confused on how to connect the ground. I have adept knowledge about the concept of ground, I just want to know how to connect the ground(0V) in this schematic to a breadboard. I'm just playing the basics  in falstad but I got confused about this.
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What would be the least expensive way to boost a DC voltage?   The aim is to convert 1.2&nbsp;V/1.5&nbsp;V (from an AA/AAA cell) to 3.3&nbsp;V to power a small 8-bit microprocessor, like Atmel ATtiny45 or ATtiny2313, and also (if possible) 6&nbsp;V to power a buzzer.  Also, what would be the maximum current one could draw safely from an alkaline battery, after boosting it to 3.3&nbsp;V/6&nbsp;V?  Finally, how I could compute the duration for which the alkaline battery would last, given a certain consumption?
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I've been trying to make a current source, and have finally gotten my hands on some  which should be an 'unlimited cap drive' op-amp. The problem is, it is still oscillating. This is the schematic and PCB layout:   I have tried to route the ground inside the loop area, close to the 5V connection for the opamp, so I could place the bypass capacitors as close as possible. Although the bigger 10uF cap has one of its legs at the groundplane (forgot to include this cap in the schematic picture.) This is what it looks like when I probe the gate of the MOSFET:  It's all over the place. I tried adding a 10uF capacitor across the DUT, so from VDD to ground. This removed a lot of the wierd noise and made it look almost like a sinewave:  I've tried with and without the gate resistor R1, it didn't seem to make any difference. What is going on? Any clues on why this just doesn't work? EDIT: Solved it! With the help from @Andyaka below, I used his solution of inserting a BJT emitter follower in between the op-amp and the MOSFET, together with an integrator and got some great results! Final circuit:  The simulations can be seen here:  The gain/phase bode plots I made on the PCB:  Bandwidth of approximately 350kHz! Very pleased.
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If Conventional Current is backwards, how do I look at something like this schematic and trace the flow of current?  I'd like to follow the design linearly from positive to negative.    When the battery is on, does current go to 8, then 4, then through R1 and so on?  Does the current get "back around" to the side of the capacitor, 1, and the speaker eventually (though fast)?  How can this be so if in reality electrons flow from negative to positive?  Edit:  If the current were water here, how would I see that physically on the wiring, as if they were pipes?
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This question is about voltage induced in a inductance.  I know the rate of change of current induces EMF in the inductor. The direction of the induced EMF will be opposite to the change that is causing it. The EMF induced is given by the following formula.  $$V_l = -L \frac{dI}{dt}$$  The negative sign indicates direction of induced emf across the coil is opposite the current change.     In the picture I have drawn current direction and \$V_l\$ direction.  If \$\dfrac{dI}{dt}\$ is postive, \$V_l\$ will be negative according to formula right? Or does the direction of \$V_l\$ has to be reversed?  In many Internet references I found \$V_l = L \dfrac{dI}{dt}\$. Which one is correct?  I hope they reversed \$V_l\$ reference points and removed the negative sign in the formula. Please clarify.