Unanswered Questions
712 questions with no upvoted or accepted answers
3
votes
1
answer
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Reforming an electrolyctic capacitor and stopping the procedure before the suggested time
Many manufacturers suggest reforming an electrolytic capacitor after it has been stored for a long period. For example, Vishay describes this process:
(source)
An increase in ESR could happen because ...
CommunityBot
- 1
3
votes
0
answers
155
views
Found a bizarre looking capacitor
I found these capacitors from a broken test equipment in my lab. I guess these are capacitors since the component label starts with 'c'. But I'm not 100% sure what they are exactly. I've also noticed ...
- 15.7k
3
votes
0
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96
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How to indicate an android tablet is actively charging with LED?
I am a rank beginner, and I do feel like I am missing something pretty obvious here, as the problem doesn't seem that complex. (I know... famous last words)
Problem:
Android tablet (in a completely ...
Null♦
- 7,623
3
votes
0
answers
2k
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Supercapacitor spot welder - which capacitors to use?
I built a spot welder using a big transformer (approximately 4kW from an old welding machine) but I now need to build a spot welder with more power (more current.)
The current spot welder works great ...
- 72.5k
3
votes
0
answers
276
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Arrangement of Capacitors in a Railgun
Nearly all of the railgun designs I've seen have arranged the capacitors in parallel. Why is this? If one arranged the capacitors in series, couldn't they achieve a higher voltage (and thus more ...
- 151k
3
votes
0
answers
133
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Discharging high voltage and capacitance capacitor?
I need to discharge a 4.4mF (millifarads) capacitor storing 1200V in about 5 seconds. I did the t=R*C' and got a resistance value of approximately 227ohms. I did a ...
- 72.5k
3
votes
1
answer
94
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A conductive ball connected to a capacitor
I am not asking for a task solution, but rather how to solve a problem.
Say I have a ball of radius R, charged to a voltage of U (relative to the ground).
I also have a flat capacitor with a side ...
- 25.3k
3
votes
0
answers
895
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PCB trace caps (a.k.a. finger / interdigital caps) formula
I am trying to calculate a two-fingered, both on the same layer, capacitor. I have run into a few papers on it but they are taking a ground plane on the other side of the PCB into consideration and ...
- 177k
3
votes
2
answers
1k
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How does this circuit with three transistors work?
I don't understand how this circuit works. Its a clap switch circuit with transistors. I would appreciate if someone could explain how the current flows through the circuit and which transistor turns ...
CommunityBot
- 1
3
votes
0
answers
315
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Formulas for Integral Components
Formulas for Integral Components:
I am looking for "simple" approximative formulas for integral components. In particular for:
A grounded interdigital capacitor (i.e. above a ground plane and with ...
3
votes
1
answer
342
views
What characteristics for 3D-printed capacitors made of interlacing conductive filament?
There are conductive filament for 3D printers which seem to have between 30 and 115 ohm/centimeter resistance depending on the axis. (Proto-Pasta conductive PLA)
They can be 3D printed as a capacitor ...
2
votes
2
answers
104
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Circuit that turns on an LED and turns it off after some time
I want to create a circuit that turns on an LED when a switch is flipped and automatically turns it off after some time. I use a capacitor for the timedelay.
Because I want it to be able to be reused ...
- 31
2
votes
1
answer
77
views
How can I calculate the resistance-capacitance values in an analog computer model?
This is the circuit design for this differential equation:
$$\frac{d^2V_o(t)}{dt^2}+2\frac{dV_o(t)}{dt}+11 V_o(t)=V_i$$
Capacitor and resistor values don't add up for this circuit. How should I change ...
- 9,270
2
votes
0
answers
58
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Typical load examples for RL and RC series and parallel circuits
I have already learned theoretical description of RL and RC circuits and their behavior. But now with a benefit of hindsight I have never truly learned about typical real world loads that have similar ...
- 121
2
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0
answers
84
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How to choose bulk aluminum capacitor value and amount for PCB supply input?
Is there a general rule to follow when spec’ing bulk aluminum capacitors for PCB power supply? I have a 24-32 V input that is 1-2 A nominal and 5 A spikes. I was thinking 2 x 220 uF 63 V caps, however ...
- 169k