Activity for Olin Lathropâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Edit | Post #282575 | Initial revision | — | over 3 years ago |
| Answer | — |
A: Battery voltage: to boost or to connect in series. To summarize the problem, you have 12 V battery packs that you don't want to change due to certifications, but you need to power a 48 V 4 A load. The battery system also needs to be compatible with an existing charger that is meant to charge each of the 12 V packs with the negative ends tied togethe... (more) |
— | over 3 years ago |
| Comment | Post #282572 |
You say the electronics needs 4 A at 12 V, and that it has been redesigned to use "up to" 48 V. Can it still run from 12 V? You say one option is to increase the 12 V to "48V and 4A". Does the new redesigned circuit now require 4x the power? Why not 48 V and 1 A? (more) |
— | over 3 years ago |
| Edit | Post #282545 |
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— | over 3 years ago |
| Edit | Post #282545 |
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| Edit | Post #282545 | Initial revision | — | over 3 years ago |
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A: Trouble understanding how to use adjustable LDO regulator Your question is quite long, so it's not clear what exactly you are asking. It seems the main point is what Microchip means by Note 5 on page 7 of the datasheet: You are right, that makes no sense. Fortunately it's so clearly inconsistent with itself that you know it's wrong. Not all datash... (more) |
— | over 3 years ago |
| Edit | Post #282363 |
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— | over 3 years ago |
| Edit | Post #282363 |
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— | over 3 years ago |
| Edit | Post #282363 |
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— | over 3 years ago |
| Edit | Post #282363 |
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— | over 3 years ago |
| Edit | Post #282363 | Initial revision | — | over 3 years ago |
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A: Help with differential to single ended voltage converter First, let's draw the schematic properly so that it's not so annoying to look at: Yes, it's a differential amplifier. Q1 sinks current as a function of VIN+. Q3 and Q4 are a current mirror that takes the current sunk by Q1 and dumps a current of the same magnitude onto Q2. When VIN- is a li... (more) |
— | over 3 years ago |
| Comment | Post #282265 |
@Carloc: If you feel something is wrong and downvote, the author really deserves an explanation unless it's just a crackpost post (which I think we can agree is not the case here). That way the author knows what to address and who to ping in case the error is fixed (so that the downvoter can undo th... (more) |
— | over 3 years ago |
| Comment | Post #282288 |
Why was this downvoted? The author has clearly put some effort into this answer. If he got something wrong, then he should at least be given the courtesy of being told what that is. Sorry I can't help here. These battery details are beyond my expertise, so I'm not voting either way. (more) |
— | over 3 years ago |
| Comment | Post #282265 |
Why did this get downvoted? (more) |
— | over 3 years ago |
| Edit | Post #282266 | Initial revision | — | over 3 years ago |
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A: Unexpected phase shift in results I get a phase shift of 90 degrees between voltage of the capacitor and current through the capacitor which doesn't make sense it should be 45 degrees You don't need a whole circuit to see that the phase shift should be 90°. You can see that from a capacitor in isolation. The current thru a... (more) |
— | over 3 years ago |
| Comment | Post #282194 |
@Dave: Good point. You should write an answer with that. Another way of looking at this is that the equation of capacitor voltage as a function of driving voltage will have a state variable. That state variable represents the charge on the capacitor. (more) |
— | over 3 years ago |
| Edit | Post #282194 | Initial revision | — | over 3 years ago |
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A: Current and voltage in AC circuits without impedance Since this is homework, I'm not just going to give you the answer. When all else fails, go back to first principles. That's what handy shortcuts, like using impedance, were derived from. In this case, you'll end up with a system of differential equations. You have already written the equation... (more) |
— | over 3 years ago |
| Comment | Post #282160 |
@leventov: There are so many opinions out there, it's way beyond us to judge which are best. We leave the presentation to the authors. The help only tries to give guidance on what the content and level of detail of a paper should be. (more) |
— | over 3 years ago |
| Comment | Post #282160 |
@manass: I agree that a writeup about driving LEDs would make a good paper, as long as the detail is sufficient, and the underlying theory is explained. The equivalent of two printed pages would probably be a good minimum length. (more) |
— | over 3 years ago |
| Edit | Post #282160 | Initial revision | — | over 3 years ago |
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A: Questions about the style of "Papers" say that materials should be small and focused There are many many theories of how to best present information. Any one or two particular opinions aren't really relevant, especially since there is a such a broad range available. The point of what you quote was mostly to set the expectation tha... (more) |
— | over 3 years ago |
| Comment | Post #282154 |
I don't know what you mean by "kinetic" in this context. Surely you don't mean the inertia of ions travelling thru the electrolyte. There is a significant voltage step from charging a cell at 1C, to immediately after disconnecting the cell. In other words, the cell exhibits some effective series r... (more) |
— | over 3 years ago |
| Comment | Post #282154 |
@coquelicot: The inner workings of electrical components is on-topic here. I don't know how many people that visit here have the expertise to answer this question, though. Most of it is over my head. It would be good to have some electro-chemical experts here. (more) |
— | over 3 years ago |
| Edit | Post #282139 |
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— | over 3 years ago |
| Edit | Post #282139 |
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| Edit | Post #282140 | Initial revision | — | over 3 years ago |
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A: Meaning of some components around voltage reference in SMPS At first glance, R22, C22, and C23 look like a compensation network around the TL431. However, this doesn't make much sense because the TL431 is being run open loop. Rfbt and Rfbb divide down the output voltage. The TL431 is turned on when that reaches 2.5 V. The TL431 is therefore used to compar... (more) |
— | over 3 years ago |
| Edit | Post #282139 | Initial revision | — | over 3 years ago |
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A: Contactor control - Higher voltage PWM Your basic idea is fine, but your implementation is not. C1 makes the whole thing not work, as it will block DC. C2 puts a burden on the switch. D1 would preferably be Schottky. I'll write a more detailed answer when I have time, probably tomorrow. I'm back now and have more time to answ... (more) |
— | over 3 years ago |
| Comment | Post #282053 |
@Lundin: Actually the right kind of box doesn't need to be large. The walls can be in the near field as long as they appear as more space to the antenna. There are actually RF boxes built on this principle. You need just the right ferrite tiles so that the walls have the same 377 Ω impedance... (more) |
— | over 3 years ago |
| Comment | Post #282053 |
@Lundin: No, a "metal box" around an antenna would have a major effect on the antenna if in the near field, and would reflect the signal from the antenna back on itself if in the far field. If that metal box were lined with ferrite tiles, then it can work at some frequencies. You have to carefully ... (more) |
— | over 3 years ago |
| Edit | Post #281974 | Initial revision | — | over 3 years ago |
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A: Is there a way to reliably measure antenna return loss outside a lab? It sounds like you are doing the measurements right. However, I expect the problem is in the space around the antenna. At 434 MHz, the wavelength is 690 mm or 27 inches. Everything out to about a meter or 1½ m should be considered near field, and can effect the antenna directly. This inc... (more) |
— | over 3 years ago |
| Edit | Post #281970 | Initial revision | — | over 3 years ago |
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A: What is the popular 12 V DC jack connector? There is no "standard" 12 V DC jack. Asking end users to buy a separate power supply is asking for trouble. Don't expect users to know about center-positive versus center-negative, and inner and outer barrel diameter. If this is an OEM product, then you can provide binding posts or even just lab... (more) |
— | over 3 years ago |
| Edit | Post #281969 |
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— | over 3 years ago |
| Edit | Post #281969 | Initial revision | — | over 3 years ago |
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A: What is the purpose of paralleling capacitors on the input/output of a power converter? Lower ESR can sometimes be a reason, as you say. However, most of the time the advantage is a wider frequency range over which the combined capacitor has low impedance or low dissipation. The frequency capability of a capacitor depends on its type, and generally reduces with higher capacitance. ... (more) |
— | over 3 years ago |
| Comment | Post #281549 |
@coq: It is not evident at all how pins are connected when not shown. To show an unconnected pin, show it with nothing connected. The quality of a question is *always* relevant. When volunteering, it is totally the volunteer's call as to what constitutes wasting of time. (more) |
— | over 3 years ago |
| Edit | Post #281549 |
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— | over 3 years ago |
| Edit | Post #281549 | Initial revision | — | over 3 years ago |
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A: Is this AD8307 fake? I am not familiar with that chip, and only took a very quick look at the datasheet. Here is the block diagram of the part from the top of the first page: A few things pop out from this: This chip has a differential input on pins 8 and 1. You tied the negative input to ground via a cap, bu... (more) |
— | over 3 years ago |
| Edit | Post #281492 |
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— | over 3 years ago |
| Edit | Post #281492 | Initial revision | — | over 3 years ago |
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A: Estimating the input capacitance of an BLDC motor controller What is seems you really want to know is how to size a power supply filter capacitor, not what the input capacitance of something is. The objective is to keep the ripple voltage below some value. To determine ripple voltage, you need to know the characteristics of what charges the capacitor, and ... (more) |
— | over 3 years ago |
| Comment | Post #281478 |
The title asks about input capacitance, but then the body seems to be asking about a power filter capacitor. What are you really asking, and what is a "BLDC inverter"? BLDC is common for "brushless DC" motor. Do you mean a controller or driver for such a motor? What is "inverter" supposed to tell... (more) |
— | over 3 years ago |