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Activity for Olin Lathrop‭

Type On... Excerpt Status Date
Edit Post #292691 Initial revision 8 months ago
Answer A: Why did the battery blow out?
Those batteries must be for powering electronics that receives commands from your controller or remote. They don't have anywhere near the energy to raise something like the headrest of a normal bed. However, that has nothing to do with why one of them failed. I've never seen a 9 V battery fail l...
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8 months ago
Edit Post #292690 Initial revision 8 months ago
Answer A: Which transistor type to use for charge shuttle, as part of an active charging circuit?
You need something with very low on-state voltage drop. That effectively means some type of FET. Those look resistive when on, as opposed to a voltage source like a BJT does. You need to look carefully at the voltages when the switches are supposed to be off. The body diode of MOSFETs and the g...
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8 months ago
Comment Post #292541 The sine will be infinite in time, not voltage. I have edited the answer to make that clear. Also, a 1 V step input will result in less than 2 Vpp sine due to the two inductors acting like a divider.
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8 months ago
Edit Post #292541 Post edited:
8 months ago
Edit Post #292541 Initial revision 9 months ago
Answer A: Analysis of LC circuit using intuition
A quick intuitive way of looking at this circuit is that the voltage source, L1, and L2 can be thought of as a lower voltage source with a single lower inductance in series. This is the same as finding the Thevenin equivalent if L1 and L2 were just resistors. Put another way, L1 and L2 are in paral...
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9 months ago
Edit Post #292527 Initial revision 9 months ago
Answer A: Connector rated voltage vs IPC-2221B and IEC 62368
If I use this connector at its rated working voltage, does that automatically mean I am not complying to IEC 62368 safety standard? The pattern you reference seems to assume one side of all eight signals are tied together. If that is really true, then I don't see how to interpret working voltage ...
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9 months ago
Edit Post #292496 Initial revision 9 months ago
Answer A: Issue in Cable Sizing and control cable selection
200 HP is 147.1 kW. At 480 V, it takes 306 A to transfer that much power. You didn't say, but your 480 V power feed is probably three-phase, and the motor is three-phase too. I don't remember how exactly that reduces the current requirements in each of the three conductors, so let's just say you...
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9 months ago
Edit Post #292309 Initial revision 10 months ago
Answer A: Do hobbyist slabtop Wi-Fi modifications need to consult FCC regulations?
is it possible that moving around laptop antennas does not change the specifications drastically, because, for example, the antennas are low-power The radiated power is probably not low compared to what is allowed. Laptops with limited WiFi range don't sell well. The limit could also be in the...
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10 months ago
Comment Post #292235 Clicking on that link goes to a page that pops up something about permissions. No thanks. Not going to look further. Please provide a proper link.
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10 months ago
Edit Post #292148 Initial revision 10 months ago
Answer A: Purpose of resistance between SENSE/FORCE line of power supply
I see that Nick has already provided a good answer to R5, so I'll only address this: Furthermore, an amplifier symbol called "gm" is labeled as transconductor. What does it do? What you show is a rough diagram only intended to give enough insight into the internal workings to use the power supp...
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10 months ago
Edit Post #292090 Post edited:
11 months ago
Edit Post #292090 Initial revision 11 months ago
Answer A: Circuit for earth conductor presence detection
The section you quoted says: "by injecting a small amount of current into the ground". With a solid ground connection, the voltage on their ground pin shouldn't change no matter what current is injected onto it. If they inject a current and see a resulting voltage change, then they know the groun...
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11 months ago
Edit Post #292089 Initial revision 11 months ago
Answer A: CAN bus open circuit detection
There is no direct way to determine whether the PIC is connected to a CAN bus. Part of the problem is that the PIC never directly connected to the CAN bus anyway. There is a transceiver chip like the MCP2551 between the PIC and the bus. The PIC interfaces to the transceiver via two digital signals...
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11 months ago
Edit Post #291984 Initial revision 11 months ago
Answer A: How to operate a chip very close to its absolute maximum voltage?
3.6 V is not the absolute maximum voltage. The table you show explicitly says "Recommended Operating Conditions". Therefore, running the chip up to 3.6 V is perfectly fine.
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11 months ago
Edit Post #291936 Post edited:
11 months ago
Edit Post #291936 Post edited:
11 months ago
Comment Post #291934 The title of your question doesn't match the content. The title talks about "very low currents", but this is not brought up in the question at all.
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11 months ago
Edit Post #291936 Initial revision 11 months ago
Answer A: Are LDOs more efficient than switching regulators in very low currents?
Do the math. At 5 V in and 1.2 V out, a linear regulator is limited to (1.2 V)/(5.0 V) = 24% efficiency. At 3 V in, the limit is 40%. The actual efficiency will be little less due to the current that the regulator itself uses to operate, but compared to 150 mA that will be negligible with pretty...
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11 months ago
Edit Post #291841 Initial revision 12 months ago
Answer A: Using only ceramic capacitors on an input of an SMPS - unclear advice from manufacturer
First, note this only applies when the line to the input power source is long enough to have significant inductance. If the power source is on the same circuit board, then this isn't an issue. They are modeling the input power feed like this: This is basically an L-C tank circuit with no w...
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12 months ago
Edit Post #291741 Post edited:
12 months ago
Comment Post #291745 I can replicate this, as you describe.
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12 months ago
Edit Post #291741 Initial revision 12 months ago
Answer A: Missing voltage rating
They don't outright tell you the maximum operating voltage, probably because that would imply a power level beyond what they think anyone would use this connector with. Note that it is intended for 50 &Omega; transmission lines. 100 VAC would imply 200 W. There are two clues in how they test the...
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12 months ago
Edit Post #291716 Post edited:
12 months ago
Edit Post #291716 Post edited:
12 months ago
Edit Post #291716 Initial revision 12 months ago
Answer A: STM32. What should be done in firmware for VBUS detection through a GPIO pin?
What should the firmware do when it detects that VBUS (re)appeared? What should the firmware do when VBUS has disappeared? I'm not familiar with the STM32 USB library, and have only dealt with this on PICs using my own USB library. I'll therefore answer the generic case. The most important th...
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12 months ago
Edit Post #291671 Post edited:
12 months ago
Edit Post #291671 Post edited:
12 months ago
Comment Post #291670 It's rather odd that your ground point is connected to a Professional Engineer. They aren't always that well grounded. From context I'm guessing you mean Physical Earth? That's not a common abbreviation I'm aware of.
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12 months ago
Edit Post #291671 Initial revision 12 months ago
Answer A: ESD Table Earth Bonding Points - Why?
I've never been involved with the design of an ESD table, so I can only imagine some reasons to put grounding connections at the front: For convenience. If you've got a table specifically for ESD reasons, you want to be wearing a wrist strap or ankle strap connected to ground. That has to be con...
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12 months ago
Comment Post #291464 Don't create new questions to get around old ones being closed. Fix the existing question. There are still many things wrong even with your "fixed" version, like Hello/Thanks, lower case "i", formatting that makes no sense, the schematic in the top picture too small to read, etc. Clearly you hav...
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about 1 year ago
Edit Post #291464 Question closed about 1 year ago
Comment Post #291461 I closed this question because it was too sloppy. We do engineering here, which includes attention to detail. I gave up at the second "i". You talk about 5 FETs, but I only see 3. The schematic is very hard to read because it's so small. Certainly you can see this for yourself. You could easily ...
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about 1 year ago
Edit Post #291461 Question closed about 1 year ago
Edit Post #291451 Post edited:
about 1 year ago
Edit Post #291451 Initial revision about 1 year ago