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1500 questions
24
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3 answers
How long would a 150 farad capacitor light up an LED?
I have a bright white LED from a flashlight. Approximately how long will it light up with a 150 farad 2.5 volt capacitor? Do I need a resistor? If so, how many Ω? The capacitor is a Maxwell 150 farad 2.7 volt boostcap model # "BCAP0150 P300 S17"…
skyler
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Is there any way to simulate a program run before burning it onto the board?
Programs may, at times, have runtime errors. These are sometimes hard to find and can easily be missed. Is there any way to test the program before actually burning it onto the board ?
asheeshr
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24
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7 answers
Good book for non-beginner firmware development
I do a lot of firmware work at my job, but I'm looking for more advanced books on the topic. Things not like the basics of "what is an interrupt". I'm reading the O'Reilly book on embedded systems development which is OK, but not advanced enough. …
Seidleroni
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24
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4 answers
How are "long push buttons" done? (For example, a "factory reset button" that has to be pushed for five seconds.)
I used a "factory reset button" a few days ago, and wondered how they make it activate only after a few seconds. Are there standard solutions to that? My best idea was to use something analogous to an RL low pass filter that takes a while to set…
BipedalJoe
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24
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3 answers
Batteries in series with different amp-hour ratings.
I have a 1.5 amp-hour, 12 V battery and I have a 10 amp-hour 12 V battery. I know the voltage will increase to 24 V when they are put in series, but I don't know what goes on amp-hour wise.
Does the new amp-hour rating take the amp hour of the low…
skyler
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24
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3 answers
Scam? Does having this capacitor wired as shown provide any surge protection?
Bought this on Amazon as a dryer 240V SPD. I was trying to find out if this device is an outright scam. I found a similar post on here from several years ago but that did not answer my question. Apparently this device was originally sold as a "power…
Jason P
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24
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7 answers
SMD vs. Through-hole components in high vibration environments
This is more of a opinion question than a information question. I am designing some boards that will be working near decent sized actuators, so I ask you, what is more resistant a 0805 SMD or a 7mm thru-hole resistor?
J.P.Wack
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24
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6 answers
Standard via sizes?
Is there a standard for via sizes, or can you make them any size you want?
(I'm going to be using traditional PCB houses to manufacture my PCB's.)
Thomas O
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24
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9 answers
Why don't LEDs have built-in resistors?
A night of struggling to fit 16 current limiting resistors into a small breadboard for a uni project made me wonder why LEDs don't have any kind of internal resistance? I can't think of any downsides. I've never connected an LED without a resistor…
Soumil
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24
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6 answers
Could data transmission power consumption be lessened by transmitting more zeroes?
According to the IEA 250 TWh of power was consumed in 2019 due to data transmission globally, about 1% of worldwide electrical power use.
I would like to pose a very simple question regarding power consumption in data transmission. Does it use more…
Fiach Reid
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24
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5 answers
Why does my 120V 40W lightbulb only have 26 ohms across it?
I thought that if the voltage source is 120V and the lightbulb is 40W then the current would be 1/3 of an ampere meaning that the resistance of the lightbulb would be 360 ohms. But when I checked it with my multimeter, it was only 26 ohms. The…
ratsmisimo
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24
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9 answers
Wire broke off and stuck in a header
I'm working with an Arduino, and one of the stripped portions of the wire broke off at some point and managed to get pretty wedged into the 5V pin slot. Obviously, this wouldn't matter as much for a GPIO pin, but I sort of need to use the +5V…
sofly
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24
votes
4 answers
Why use kapton tape?
I have noticed a lot of electronics use kapton tape in places where a heat resistant tape isn't necessary. Why is that so? Is it just because it's a good adhesive?
Artichoke
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24
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3 answers
What is "offset null" in IC 741?
What is Offset null in 1st and 5th pin in IC 741 (Op-Amp)? Why it is used, though it is not used in many circuits? Give me explanation regarding the offset null!
Why offset voltage was formed in IC 741?
Abishek ram R
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24
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3 answers
Why are so many batteries 3.7V?
This seems like a very common voltage.
I remember older batteries used more round numbers like 1.5V or 3V or 9V.
3.7V seems very arbitrary but seems to be everywhere.
oshkosh
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