New answers tagged resistors
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Do I need a resistor in circuit when charging capacitors?
"Will the capacitors charge quick enough not to cause any harm?"
What do you mean by "not cause any harm"? very high peak currents for a short period may or may not cause damage to ...
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1
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Do I need a resistor in circuit when charging capacitors?
This depends on which phase of the network the capacitor begins to charge. The worst case is peak values, meaning that all the current will be applied to the ESR of said capacitor. In turn, this ESR ...
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How to determine the collector current limiting resistors for the Darlington's pair of transistors?
They're not particularly critical. Most of the current consumption is in the output circuit.
You can use the same values except replace [220Ω + buzzer + LED] with [1.5kΩ + LED] for about 5mA through ...
- 383k
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What is the best way to use 0 ohm resistors for a large number of signals?
It may not be appropriate in your particular case, but you can get x4 (and other multiples, but x4 is more common) zero-ohm networks. Image from lcsc shows a part measuring 1 x 2mm overall.
- 383k
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What is the best way to use 0 ohm resistors for a large number of signals?
Those of us old enough to remember configuring motherboards know that if there are a lot of these to do, there are really two options: switches (available in SPST and SPDT, at the very least) and 0.1&...
- 29.6k
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Accepted
Phase difference between voltage across a capacitor and the source in a low pass filter
Well, the transfer function of the circuit is given by:
$$\underline{\mathscr{H}}\left(\text{j}\omega\right):=\frac{\displaystyle\underline{\text{V}}_{\space\text{o}}}{\displaystyle\underline{\text{V}}...
- 7,368
0
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Phase difference between voltage across a capacitor and the source in a low pass filter
Just use Voltage Divider Law on the two components....
Vc/V = ZC/(ZC+ZR) = (1/jwC)/(R+(1/jwC)) = 1/(1+jwCR)
Then use standard phase (and magnitude if you wanted to) equation, arctan(imaj/real).
Angle ...
- 441
2
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Phase difference between voltage across a capacitor and the source in a low pass filter
Mixing frequency domain with time domain won’t work. Pick one or the other.
The impedance of capacitance \$Z_C=-jX_C\$ is a frequency domain quantity:
$$
Z_C(j\omega)=\frac{-j}{\omega C}
$$
The first ...
- 13.5k
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Why is the voltage across a capacitor in the Laplace domain equals I(s) / s?
Why is the voltage across a capacitor in the Laplace domain equals I(s) / s?
It isn't.
\$1/s\$ means integration, so \$I(s)/s\$ means integrating \$i(t)\$ over time i.e. \$\int i\ dt\$. This is ...
- 30.2k
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Why is the voltage across a capacitor in the Laplace domain equals I(s) / s?
Well, the current in the circuit is given by:
$$\text{I}\left(\text{s}\right)=\frac{\displaystyle\text{V}_\text{source}\left(\text{s}\right)}{\displaystyle\text{R}+\text{sL}+\frac{\displaystyle1}{\...
- 7,368
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How can I convert a Noma Ornamotion Christmas tree ornament motor to USB power?
I did this a long time ago with transformers. Sorry, I don't remember the transformer part number, but I matched the voltage as close as I could. I may have used 1/2 of a center tap.
I also have some ...
- 14.8k
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Help identifying 4-ring resistor with extra band which has gone open circuit
This is probably a fusible resistor, providing circuit protection as well as voltage drop.
See the link above to the tag wiki for more details on how to identify, but like a fuse it is important to ...
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Identifying a resistor with a weird band combination
The body colour, 4 ring code + extra band, circuit location and open circuit failure, strongly suggests this is a fusible resistor designed to fail open circuit toprotect the rest of the device.
As ...
- 5,741
2
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Resistor switch
You can use a 249Ω resistor and a 1/(1/33-1/249) Ω resistor switched in parallel with it , which works out to 38.3Ω (a standard value), giving you nominal 249Ω and 33.2Ω.
If you want to get a bit ...
- 383k
4
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Accepted
Resistor switch
Yes. Use this schematic:
R1 has to be 249 Ω so that it reads as 249 Ω with the switch open. We need to calculate R2, however, which you can do as follows:
$$R1 || R2 = 33\ Ω$$
$$249\ Ω || R2 = 33\ Ω$$...
- 29.9k
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How can I drop 24v DC to 12v DC with resistor(s) in my old tractor?
What size resistor(s) would I need to replace this resistor in order to drop the voltage from measured 24.5v to 12v not knowing the value of the original?
This isn't possible to know with the given ...
- 128k
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Selecting Balancing Resistors for HV Capacitor Bank
You can model this as a ladder of paralleled resistors:
RTotal = (RCap1 || RBal) + (RCap2 || RBal) + ...
Now you need to choose the balancing resistors so that no ...
- 15.5k
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Purpose of this resistor in a low-pass filter
Without \$R_3\$ (and ignoring \$C_2\$ for a moment) the gain equation from op amp's output to the signal input would be
$$
G=\frac{V_o}{V_i}=-\frac{R_2}{R_1}\frac{s}{s+\frac{1}{R_1C_1}}
$$
But with \$...
- 30.2k
-1
votes
Reducing the AC voltage using resistors
First you must rectify the AC with a diode. Your rectified voltage will be like 1.414 higher than the AC voltage.
Now you can put a resistor sized by the current you need, a Zener diode rated 5 V, and ...
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NPN transistor small output voltage
Thanks all for your insight on this topic. I also struggled with this circuit with my ESP 12F attempting to drive a 5v Laser from GPIO4. What I come to find out was that NPN was "above" the ...
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What is going on inside this light dimmer?
The ballast can contain a very simple current source, not necessarily a constant current source IC. It could be a 600R resistor from a 12V rail, so that when the dimming pair is shorted out you get ...
- 8,340
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How do basic voltage drop calculations work?
1-resistor circuit
Why does the full voltage drop in the first 10 ohm resistor and why does it drop fully before it reaches the negative of the source battery?
The only way to find out why is to &...
- 14.9k
2
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Accepted
How do basic voltage drop calculations work?
simulate this circuit – Schematic created using CircuitLab
The battery produces a potential difference (voltage) across it of 10V. That's its job, to ensure that one of its terminals (the ...
- 28.8k
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Accepted
If I have a 500ohm resistor in series with 3V motor, with an input voltage of 5V, will it work?
It will work if the motor draws
$$
I = \frac{2V}{500\Omega} = 4mA
$$
For currents above that the motor will get less than 3 V, for currents less than that the motor will get more than 3 V. The motor ...
- 19.5k
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Resistive network with two voltage sources
I think having more than one of the Rr resistors in circuit allows solution of the problem using a relatively straight forward approach.
The outline approach is as follows:
Insert the R3 Rr resistor.
...
- 5,741
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Resistor suggestions for colorblind person
I would assume that resistor manufacturers are all color sighted. Most color sighted people do not give a second thought to the fact that color actually does not exist. This fact does not prevent them ...
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Derivative of the current through a resistor in an RLC circuit
You are looking for intuition. Not sure if the following helps there. But it's my shot at it, adding to the existing pile.
The current in the inductor+resistor branch must be 0 (assuming no initial ...
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Derivative of the current through a resistor in an RLC circuit
I think your solutions manual has the better approach. At the instant the current source turns on, the capacitor acts like a short circuit, absorbing all the current. This causes the rate of change of ...
- 21.5k
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Derivative of the current through a resistor in an RLC circuit
I transformed the circuit according to Laplace, then I calculated the Laplace transform of the current i(t) i.e. I(s), considering it as the partition current of the parallel composed of C and the ...
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Derivative of the current through a resistor in an RLC circuit
Well, the current trough the resistor \$\text{R}=4\space\Omega\$ can be found using Laplace transform:
$$\text{I}_{\space4\space\Omega}\left(t\right)=\mathscr{L}_\text{s}^{-1}\left[\frac{\...
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