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Activity for Olin Lathrop‭

Type On... Excerpt Status Date
Edit Post #284046 Initial revision about 3 years ago
Answer A: Inductance vs frequency
No. An inductance is an inductance. One way to look at an inductance is as an impedance that is a function of frequency: &nbsp; &nbsp; Zind = &omega;L = 2&pi;fL Where Zind is the impedance magnitude of an inductance, &omega; and f the applied frequencies, and L the inductance. When &omega...
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about 3 years ago
Comment Post #283958 OK, but don't tell me here, <i>fix the question</i>.
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about 3 years ago
Comment Post #283958 How coupling effects the series inductance is a good question, +1. However, it's ambiguous to talk about the inductance "of this circuit". Do you really mean the two inductors in series? Do you mean the inductors and resistor as view from the voltage source?
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about 3 years ago
Comment Post #283956 No, 2(4/9) <b>is</b> dimensionless. That's what you wrote.
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about 3 years ago
Comment Post #283956 Seriously!? Just read the whole post looking for errors. Obviously you haven't done this yet.
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about 3 years ago
Comment Post #283956 Whether one can guess the units is not the point. It's still <b>just plain wrong</b> to equate a value of Volts to a dimensionless quantity.
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about 3 years ago
Comment Post #283956 I've said this before, so this time you get a -1 right away. We do engineering here, where units are important. Every numeric value that is not dimensionless <i>must</i> be shown with its unit. Units must match on opposite sides of every equals sign. If not, the equation is wrong, just like if th...
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about 3 years ago
Comment Post #283955 Much better schematic, +1.
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about 3 years ago
Comment Post #283956 There several errors because it seems you copied and pasted this answer from your answer to a similar question about an inductor. You should carefully read over the whole post before posting, then sometimes again a while after posting. That will catch a lot of this sloppiness.
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about 3 years ago
Edit Post #283936 Post edited:
about 3 years ago
Edit Post #283936 Post edited:
about 3 years ago
Comment Post #283936 Why would I want to do that? As far as I can tell, it answers the question correctly. What do you think is wrong?
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about 3 years ago
Edit Post #283909 Post edited:
about 3 years ago
Edit Post #283936 Initial revision about 3 years ago
Answer A: Current and voltage of inductor
For reference, here is your circuit properly drawn with component designators: The question is what happens when the inductor current starts at 0, then the switch is closed. The first observation should be that the current source and the two resistors can be reduced to the equivalent Norton...
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about 3 years ago
Comment Post #283926 I told you before, always include component designators on your schematic. -1 for ignoring this requirement. Ping me when you fix it, and I'll undo the downvote.
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about 3 years ago
Comment Post #283906 Oops. Yes, I meant to say "minimum".
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about 3 years ago
Edit Post #283909 Initial revision about 3 years ago
Answer A: Select resistor for a diode
What the "appropriate" value of R1 is depends on what you are trying to achieve, which you haven't told us. Will this device be used in bright light, like outdoors, and the LED therefore needs to be as bright as possible? Is it an illumination source? Is it just an indicator, and it only needs to ...
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about 3 years ago
Comment Post #283904 The equation you use that implies the LED current as a function of the voltage across it is stated nowhere in the datasheet. You should only go by what it says in the datasheet. Also 5 digits is absurd in this case, especially due to the high temperature dependence of LEDs in general. "295.05 &Ome...
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about 3 years ago
Comment Post #283906 The general form of this answer is correct, +1. However, you shouldn't be using the typical forward voltage drop, but the worst case (highest) for the current you want. The resulting calculation that you show than results in the <i>minimum</i> resistance to not exceed the maximum current rating of ...
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about 3 years ago
Edit Post #283901 Initial revision about 3 years ago
Answer A: Diode like a frequency mixer
A diode mixer exploits the fact that the voltage across a diode is the log of the current thru it, to a good enough approximation for many uses. Now note that multiplication can be performed by taking the log of two values, adding the logs, then doing the un-log (take the exponential) of the result....
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about 3 years ago
Edit Post #283693 Initial revision about 3 years ago
Answer A: Thermal relief for through-hole on multi-layer PCB
That's a rather strange thermal relief pattern. It's also not clear where the hole is supposed to be. A proper thermal pattern has a plated hole and annular ring around the hole as usual. Then there is a gap with only a few narrow bridges connecting the annular ring with the surrounding plane. ...
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about 3 years ago
Edit Post #283663 Post edited:
about 3 years ago
Edit Post #283663 Initial revision about 3 years ago
Answer A: What is the difference between emitter and collector of a transistor?
I see you already have an answer based on the device physics. I'll answer that this means in a circuit. BJT (bipolar junction transistors) do work in reverse, at least somewhat. Generally, the characteristics aren't as good, particularly the gain. However, in most cases you still get some gain ...
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about 3 years ago
Edit Post #283659 Initial revision about 3 years ago
Answer A: SPI modes difference
"Stream" and "memory mapped" should be defined in the documentation for whatever microcontroller you are using. "Memory mapped" can mean different things. It might be just a different way of saying DMA, meaning the peripheral gets and puts data directly to memory buffers without code intervention...
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about 3 years ago
Edit Post #283587 Post edited:
over 3 years ago
Edit Post #283587 Initial revision over 3 years ago
Answer A: $Q$ and $\overline{Q}$ in bistable multivibrator
Whichever you choose. I notice that you deliberately made the gain of one transistor a little higher than the other. That is irrelevant. The positive and negative outputs don't depend on the power-up state. They depend on which way the outputs go in response to inputs, like SET and CLEAR. Yo...
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over 3 years ago
Edit Post #283453 Initial revision over 3 years ago
Answer A: A signal with one mode or with three or more modes
with just one mode Others have already explained that "discrete" means a finite set of values, not just two. This is to point out that having just one "mode" (it seems you mean symbol) doesn't make any sense. A signal that can only ever be in one value is no signal at all since it can't carry ...
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over 3 years ago
Comment Post #283361 I don't know. I thought it was a reasonable question and upvoted it. It is unfortunate that users can downvote something anonymously and without explanation.
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over 3 years ago
Edit Post #283365 Initial revision over 3 years ago
Answer A: Motor Controller - What might be the purpose of these resistors?
Reasons this is sometimes done: To get higher power dissipation. To get higher voltage capability. To get lower parasitic capacitance. For 1 and 2 the "normal" answer is to use a resistor rated for the required power or voltage in the first place. However, there are some advantages t...
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over 3 years ago
Edit Post #283331 Post edited:
over 3 years ago
Edit Post #283331 Post edited:
over 3 years ago
Edit Post #283331 Initial revision over 3 years ago
Answer A: Adding resistance to varactor circuit
in my schematic we must add R1 correct? No. Ultimately you are adjusting the varactor with a DC voltage that has a certain impedance. You can think of it as a Thevenin source. In your case, the DC voltage is created by the divider of Rs and Rv, then the impedance increased by R1. However, yo...
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over 3 years ago
Edit Post #283242 Initial revision over 3 years ago
Answer A: Is English translation of technical terms on-topic?
I think such questions are OK as long as they are EE-specific. General purpose dictionaries often do a poor job with specialized technical terms, especially when they are the same or similar as regular words in either language. There can also be nuances how EE-specific terms are used in different c...
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over 3 years ago
Edit Post #283213 Post edited:
over 3 years ago
Edit Post #283213 Initial revision over 3 years ago
Answer A: Division of binary numbers logic circuit
I dont understand how to make a logic circuit which does that job:check if the divisors is greater and equal or less than the most left digits of the divident So think about it. Break it down into small chunks. Let's ignore the reason behind your question and try to make a digital block that com...
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over 3 years ago
Edit Post #283172 Post edited:
over 3 years ago
Edit Post #283172 Post edited:
over 3 years ago