pressfit connections usually are very reliable. if there is a poor connection i would presume that the barrel of the via is broken and a new pressfit connector will not help. maybe putting solder in would help. did you already test for poor connections?
Barrel of the via? I’m unfamiliar with that terminology – what is that? I did a continuity check from the very bottom to the very top and everything tested good. When the audio is out, twisting the header a bit would usually bring it back so I assume(d) it was just a poor connection somewhere despite the continuity check.
EDIT: Okay, some quick Googling got me understanding this better. As I mentioned, continuity is good, but I still suspect it’s something in this area. I suppose I could remove the connectors and install solder connectors, instead of press fit?
yes i think so, but u would have to make sure the solder will rise through the through-hole as mich as possible. maybe u can try to find the faulty pin with wiggling them separately
I am trying to be non-destructive since this is a rare piece of equipment. So I would prefer to put in something entirely new in and preserve the original hardware in case something goes wrong.
One possiblity would be to cut the original cable and add a new connector to both sides. A female one to the one that goes to the board, and a male one to the one on the fan.
That way you have all the original parts still there, but you can use the one part of the cable as an adapter.
Any chance to replace the whole PSU and then going full tilt modifying the replacement? I only see one offer for 400-5494-91 (400€!!) so maybe any other in that form factor? Seems to be mostly standard PC connectors on these, but not sure from the pics I can find.
See if you can swap the connector, those pins can be released if you gently lift the locking tabs and pull the wire away from the connector. The metal connectors from your replacement fan might not fit into the original, but it’s worth a try.
Thanks for this suggestion! Is there any chance of breaking the connector by doing this? I replied to another commenter, but to emphasize, I am only looking to modify the fan and connector as a last resort because of how rare this equipment is.
Breaking the plastic would be tough so long as you’re not hammering it. The connectors crimped to the wires it’s another issue and if you pull too hard you could get the wire to come off the connector if it isn’t soldered.
Yes you could break the connector if you’re not careful. However at the end of the day, it’s not like you can’t replace both sides of the connector with standard hardware, and at the very worst you could solder the fan to the pins and cover each wire with heat shrink.
The smd codes kind of suck. They’re used on devices where there isn’t room for the full PN. But they’re not standardized well. Are often unique per footprint, but even then, not a guarantee.
I looked up “CAZ” here: smd.yooneed.one/code4341.html and found a part that matches the footprint. Then googled around and found the LN61CC3002MR-G on lcsc.
It can be very hard to find a part on Google, or say Digikey, if it’s made by a Chinese company. LCSC can be helpful since they’re based in China.
usually fans have a min start voltage. u can try if your fan starts at 5v and if the resulting RPM is ok for you, just solder it without any resistor on USB
If it’s for a digital or power-electronics design, you might want to bypass that question entirely and put in a plane/copper pour/copper fill (all synonyms) that encompasses all these pads.
This helps with power dissipation and lowers resistance though has parasitic inductance and capacitance ramifications. It depends on what goes through that net !
On the other hand if this is analog, high frequency, rf or mixed-signal, I would suggest looking at what kind of requirements you have for that net mathematically. You can find the parasitic inductance and capacitance equations (approximations) online quite easily.
I wouldn’t use the PAM2804. The datasheet recommends a PWM frequency of 500 Hz, and if you look at the “PWM Dimming: ILED vs. Duty Cycle” chart on page 5 you can see why - at 1 kHz there is already a significant reduction in the average LED current. The enable response just isn’t fast enough to modulate at 38 kHz - by the time you want to turn it off, it will barely be on.
This isn’t quite enough for your 38 kHz either, but it’s closer (and waaaay more complicated): MAX16834. The datasheet says it can do up to 20 kHz, but at a glance I did not see a particular spec that seems to actually limit that.
Here’s an article about fast switching LEDs. All the linked products unfortunately have supply voltage ratings above yours, so they won’t work. But it discusses the concept of shunt dimming, where you’d end up simply bypassing the current around the LED rather than actually turning off the current regulator. Inefficient, yes.
Hey, thanks for your comment. I’ll look into the MAX16834 as soon as I have time tomorrow. Also, how would I be able to use a constant current driver with shunt dimming? How would I go about calculating the time a constant current source takes to recover from a short?
How would I go about calculating the time a constant current source takes to recover from a short?
To the extent possible, I’d look for graphs of “load regulation” in the datasheet, which graphically depict the regulator’s response to a load change. But that seems like maybe an uncommon thing for LED drivers (neither of the two parts we’ve been discussing have those in their datasheets).
Alternatively, if the regulator lists its control bandwidth in the datasheet, you could use the old rule of thumb to relate that to the rise time. For instance, if you’re modulating at 38 kHz, and you want to be sure your rise time is less than 10% of a period, you’d want it to be less than 1/380,000 = 2.6 microseconds. From the article, you’d want a control bandwidth of no less than 0.35/2.6 microseconds = 133 kHz. (or you could just say you want a bandwidth at least 3.5x your carrier frequency).
Using that metric, the MAX16834 is more than capable - yet despite that, the datasheet suggests (not a hard spec) that PWM dimming is functional only up to 20 kHz. I don’t know how to explain that discrepancy. This is where I’d buy an eval kit and try it out to see what I’m missing.
Ideally the logo should be something simple, because it gets displayed in many different places and usually pretty small. ~500x500px should be enough, and the main content should be inside a circle, because the corners are often not displayed.
A more detailed artwork is better for the bigger banner. Most communities seem to use something around 2000x1000px or so.
Just a word of caution - education is a process of diminishing deception. Books provide a simplified version of real World electronics. Universities and colleges put a lot of effort into designing lab practicals that will actually work and give the predictable results that students expect.
So the normal learning process when it comes to op amps - is to read and understand the theory. Then complete those crafted lab practical exercises - having been introduced to the added complication of systemic and random errors. Then do your own thing, when all the remaining Real Life complications hit you like a brick.
So, if you can find a course in analogue electronics, even a distance learning one, you might find the steps are smaller and more easy to assimilate.
I understand your caution, however I understand the theory behind OP-Amps, theory can only go so far which is why I’m building a circuit on a breadboard now. I should clarify that the basic rules for ideal op-amps I have a grasp of, although I can never seem to remember these rules. For example, I have the formulas for a BJT and MOSFET transistors memorized because I spent a lot of time reading and using them in practical applications. Op-amps I have spent a lot of time reading but no time building circuits, which is essentially what I am trying to do now. I have a degree in EE, and at this point this is one of the basic components that wasn’t covered much in university, nor did reading or doing practice problems help. I’m very much a hands on learner, I can read formulas and equations all day but if I don’t apply what I learned I’ll forget it after several days unless I repeatedly practice.
What worked for me, that may not do so for anyone else - is to take an existing circuit (usually a reference one provided by a manufacturer) and build that. Get that working (sometimes, it hasn’t worked- the manufacturer’s technical support department has often been very helpful, especially when their reference design has a design fault or has been misprinted - after doing that, they used to send me unmarked, pre-production chips/etc to play with and provide feedback).
Then modified that design, to test my understanding. Tried different board layouts, guard rings, etc and documented the effect. When it didn’t work as expected - took that back to their tech support to see if we could work out why.
So, for me, taking something that works and keep modifying it, just a little.
However there's a weird little caveat -- some papers attribute the piezoelectric effect to organic collagen fibers. Others attribute it to the inorganic component (apatite). In the end this paper seemed to have a reasonable measurement process so I've just ignored the exact cause of the piezoelectricity for the moment. From their tests, orientation of the bone is highly important.
They use an applied voltage of 100V then amplify (100db). I'm reasonably competent working with moderate voltages, but would prefer to try something under 30v as a matter of convenience (e.g. what I can reach with a DC-DC boost converter).
Normally though, I just hook up a crystal oscillator to a hex inverter @5V or to an MCU with some caps. I'm not entirely sure how I'd build an equivalent circuit at 30V! Doing unnatural things with crystal oscillators hasn't really come up much in my studies or career.
You madlad, I don't have much to add but this would be pretty interesting if it worked. Presumably uncooked bone? I also think that using a very thin slice would increase the strength of the electric field, since you want to have a small gap between the plates (field strength is volts per meter). Does the orientation of the bone matter? Could you ask a butcher to cut a slice from a large beef bone?
I tried with cooked bone, that tends to be what I have more of lying around :D
I don't recall the voltage I tried, but it was probably something in the range of 5-9v. I didn't try with a very thin slice, it was a few mm thick. Probably a thinner slice is the thing to try. That's a bit hard with bird bones (hollow), so maybe I'll have to cook something else. I don't have a microtome, so I'll have to cut some thin slices by trial and error.
I would hazard a bet that orientation matters. The studies that measured bone piezoelectricity seemed to suggest some orientations made more sense than others, but I don't recall what exactly. In any case, they had... very different applications in mind.
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