11
votes
Accepted
Can't get 5V 3A DC constant
It seems you are making several beginner's mistakes in your understanding and application.
You are using the LM2956 5.0 which is the 5 V version. This will output a regulated 5.0 V subject to meeting ...
- 171k
7
votes
LM7805 for stable 5V output
The LM78xx series of voltage regulator have dropout voltages of 1.5 to 2 volts. All linear regulators have at least some dropout voltages, which restricts them to always having output voltages lower ...
- 45.4k
7
votes
Series Parallel batteries
When you ask a simulator to solve a circuit, it has to be able to find everything. As the voltage sources you have used are zero impedance, a loop of voltage sources could have an undefined current ...
- 162k
6
votes
This is not my circuit, but anyway, What are they?
The points labelled A, B and C are likely to be test points, to test the function once the circuit is built.
The V+ and V- are most likely the connections for the input, given the two power sources ...
- 6,519
6
votes
This is not my circuit, but anyway, What are they?
By way of a direct answer, \$A\$, \$B\$, and \$C\$ are in fact required test points. \$C\$ is actually also an output as well as a test point.
There is NO possible way to properly adjust the ...
- 77.5k
6
votes
Can't get 5V 3A DC constant
You are measuring the circuit incorrectly. Your ammeter is shorting the output, this is why you are getting maximum current.
You need a proper load, the LED is not going to work. Use a resistor ...
- 11.9k
6
votes
Accepted
Pre-amplifier for speaker
Make the 3 capacitors at least 100X bigger.
And remove that 8 ohm load.
Then resim.
You have about 0.3 volts across the Remitter. Thus about 1mA.
That makes the 'reac', which is 1/gm, be 26 ohms.
Now ...
- 33.8k
6
votes
Accepted
How can I verify the max power theorem in a buffer opamp?
Your first circuit has a 3:1 voltage divider.
Your second circuit doesn't. The op-amp input impedance is so high that the 2k resistor makes no difference. It sees the full 1.5 V of the battery.
- 171k
5
votes
5V power supply using 7805 with multiple outputs
It doesn't matter how wire you connect to the 7805's output. The only things matter is how much current you will ask for. According to the datasheet, the 7805 can provide 500mA. This mean the sum of ...
- 3,926
5
votes
Practical integrator using op-amp
It is very difficult to make a perfect integrator, so you need to decide what compromises are acceptable.
This is an inverting integrator (note that the signal goes to the minus opamp input). Change ...
- 15.1k
4
votes
Questions on Multi-stage transistor Op-Amp
It will be hard to explain this circuit if you don't have much background in electronics. Q1 and Q2 are a differential input pair. R7, R8 and Q3 create a constant current. So the constant current ...
- 29.1k
4
votes
How to design over voltage protection Crowbar Circuit?
Explaining the Simulation Results
You don't show your calculations. That's a problem. You compute resistor values to almost insane precision. That's a problem. You don't take into account that an SCR ...
- 77.5k
4
votes
Accepted
Active clipper terrible performance
TLDR:
You're going to need an opamp with a high gain bandwidth product and a high slew rate to make that circuit work. The capacitors you've added will do you no good at all.
It looks like that ...
- 69.2k
4
votes
Accepted
Multisim vs LTspice : Different Result
You have a voltmeter connected to the node in question, but only in Multisim.
The voltage difference is actually rather inconsequential in practice because it's like two leakage currents fighting. ...
- 385k
4
votes
Accepted
Can electric circuit simulation software simulate capacitor charging process
Since you measure 12 V the capacitor is already charged, which is as expected because the simulator tries to find the steady-state solution. The 12 pA shown is likely a leakage current, either ...
- 13.9k
4
votes
Can electric circuit simulation software simulate capacitor charging process
With a capacitance of 1 F and a resistance of 1 MΩ, your circuit's time constant is
$$ \tau = RC = 1\,\mathrm{F}\cdot 1000000\,\mathrm{Ω} = 1000000\,\mathrm{seconds}. $$
You would need to simulate the ...
- 7,504
4
votes
Simulation isn't working for high voltage amplifier
I found some errors in the original schematic, they are corrected.
For newer FETs, the quiescent current had to be set. I set this to 5mA with R19 and R25. (14k instead of 10k.) There is no point in ...
- 2,176
4
votes
How can I generate an exponential signal in simulation software?
In spice you have behavioral current sources (bi).
- 19.7k
4
votes
Accepted
BJT current gain: Relation of SPICE parameter BF to beta
In modeling a BJT's DC operating point, the actual forward beta is the result of iterated numerical circuit calculations where the linearized operating point of the BJT is repeatedly recomputed at ...
- 77.5k
4
votes
Practical integrator using op-amp
This is an integrator:
simulate this circuit – Schematic created using CircuitLab
What you have built is not an integrator. The presence of R2 in your circuit turns it from an integrator into a ...
- 29k
4
votes
Accepted
Summing RMS values proof
The definition for root-mean-square (rms) voltage is:
$$v_{rms}=\sqrt{\frac{1}{T}\int_{0}^{T}v^{2}dt}$$
If \$v=v_{1}+v_{2}\$ are all functions of time.
Then:
$$v_{rms}=\sqrt{\frac{1}{T}\int_{0}^{T}\...
- 13.6k
3
votes
Inverting Op Amp: Why does current flowing into output seem to magically reappear at ground?
I'm pretty sure the Boyle macromodel for 741 is causing this. In Op Amp Applications Handbook (ed. Walt Jung) p. 742 the MPZ model (well AD's flavor thereof) has this praise
output load current is ...
- 14.4k
3
votes
Accepted
How do electronic design tools work
If you really want to understand this, I highly recommend a book by Dr. Farid Najm, called "Circuit Simulation". If you follow the exercises in the book you can code a working simulator by the time ...
- 23.6k
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