On your note about capacitor sizes — at my first EE job, my boss taught me about capacitance-voltage derating[0] for ceramic capacitors and it was quite the revelation. There is a significant inverse relationship between the two, which no one tells you about in college!
I'm now very careful to pick ceramic capacitors with enough headroom on their rated voltage as you lose a lot if you're close to the rated value. This curve is dependent on the different ceramic types as well (C0G, X7R, etc). Cheaper ceramics have a steeper rolloff.
For personal projects I am very careful to pick higher quality ceramics (X7R if I can) and use caps rated to 2-3x my operating voltage. Likely overkill, but I'm not optimizing for cost at volume.
It is not actually true that MLCC DC bias derating scales with voltage rating. The voltage rating itself actually has nothing to do with it. The correlation is with package size. (Package size and voltage rating are often loosely correlated (and were strongly correlated back in the day), which is where the misconception comes from.) The physical origin of the effect is electric field strength in the dielectric material; thicker dielectrics reduce the field strength, so you don't come as close to hitting the polarizability limit of the piezoelectric materials, at a given applied voltage. Voltage rating doesn't really show up in that analysis.
If you don't believe me, poke around a bit in SimSurfing or similar. You should also notice that most capacitors are actually binned by voltage rating these days: a 16V part and a 50V part might be identically specified, but one's curves just cut off at 16V. I don't know if that's strictly binning or just testing, but it's pretty clear they're the same parts under the hood.
> It is not actually true that MLCC DC bias derating scales with voltage rating. The voltage rating itself actually has nothing to do with it.
This statement used to be false (I used to design boards where I would bump the voltage rating to get better DC bias behavior), but it looks like the engineering behind these capacitors has changed "recently" (as in the last 10 years), and it is now mostly true.
Thank you (and the GP) for the correction! I'll admit this lesson came to me a decade ago and I am speaking to a rule of thumb I developed as a result. Time to update my knowledge banks.
The other thing worth mentioning is that there are multiple formulations, and they're not all equal. Just to pick on Murata, the last character of their part number is a reeling code (something so boring it's often omitted or wildcarded), and then the three characters before that represent the specific dielectric material in use. (Or something like that. It's a private use field and I'm reverse engineering it here.) For the examples above, that's "E01", "A01", or "A88". Each of those will behave differently in SimSurfing, but all parts with the same dielectric code will have the same DC bias behavior. (At least, they will if they have the same size and value, etc. When those change too, behavior still follows the usual trends.)
Parts with different codes can have vastly different behavior under DC bias. You'll find that one of them is the clear winner in most cases. Unfortunately, Murata knows this too, and that one is invariably more expensive in distribution.
But at least you can specify it!
Other vendors do this too, but it's easiest to see with Murata's setup and tools.
I live in Alameda and this place is such a local gem. The owners are really genuine people too. Great place to spend some time!
They also own a whole warehouse out at Alameda Point filled with machines. I know they have provided some form of access to the public in the past, but I'm not sure what that looks like today.
As a former Fit owner, I wish I had thought of this! The AC was really bad. We did a lot of road trips and it really struggled out on the long desert highway stretches.
In my upper-division analog electronics class (the hard one), our lab project throughout the quarter was to build an analog computer that simulated the physics of a bouncing ball. Physical variables of the system were adjustable (gravity constant, coefficient of restitution, etc), and the ball was "released" by pressing a button. The output was viewed on an oscilloscope.
One of the hardest 10 weeks of my life, but also one of the most rewarding. Our team was one of the few that actually got it working in the end. I had to custom-make a gigantic breadboard to hold the entire circuit.
Today I still work in hardware, but mostly with digital circuits. While my analog knowledge has decayed over the last decade, that project and it's success gives me great confidence any time I have to deal with the domain.
My version of this was a 10-week discrete RF circuits course in graduate school. We had to build a fully functional GHz transceiver out of small FR4 PCBs (< quarter wavelength) and throw-away leaded BJT transistors. Neither were suitable for GHz circuits, so the course was hard by design. I learned so much and developed an intuition for electromagnetics that I still carry 20 years later.
Hey, I made something like this a couple months ago! (Except it's more like "Tennis for Two", so you also hit the ball in the X direction, and there's another button to hit it back in the other. I didn't have any space or potentiometers left to set the gravity, but it wouldn't be difficult.)
I also learned heaps! (Including after a few weeks when the circuit stopped working properly because one of the relays started to work just a little slower than another one, heh.) If anyone's interested, https://blog.qiqitori.com/2024/08/implementing-tennis-for-tw...
> Today I still work in hardware, but mostly with digital circuits. While my analog knowledge has decayed over the last decade, that project and it's success gives me great confidence any time I have to deal with the domain.
Do you think about the analog qualities of your traces when laying things out? If so then the course was well taken.
In my observations I've found that too many digital engineers assume a differential pair will save them without actually fixing the impedance and parasitic issues. Particularly as the timings of things become so much more precise analog is so important. People forget that a digital circuit is just an analog one under the covers.
Did the mathematical model being used have a differentiable heigh function? I’m imagining it would be the simplest if it didn’t but that could cause problems in the electronics.
Also what components did you have access to, just op amps?
That's really interesting. For me, I very much do NOT enjoy the taste of truffles in restaurant dishes because it's often so overbearing. I just don't find the flavor interesting, and it's very singular.
Perhaps I would enjoy the "real" experience more...
A lot of restaurants also just overdo how much they add in an attempt to make it seem like they put a lot of truffles into the dish and so there's a strong aroma from the dish. Whenever I use it, in something like my attempts at a mushroom truffle risotto, I will usually use a drop or two for a whole pan. Maybe a little more if I plan to cook the dish for a while after, such as if I am making a sauce that will simmer for a bit. Usually even a teaspoon is too much.
The source code isn't hiding in a repo somewhere for security reasons — it's spread around on various pieces of paper and computers over the last 50 years. There isn't a single source of truth. Adds a whole other level of wizardry to keeping the thing running.
It costs money that would better be sent towards other projects, and NASA needs to be as careful as possible with spending their very limited budget.
Having a ton of people run around the office for a couple months to collate a bunch of documents so you can better pass info on to a new generation of workers when the satellite might not even be usable anymore isn't very efficient. Might as well just pay an extra 50% or whatever to the 5 dudes who know what's going on until the thing is inop. Even if it died today, the mission still would've been a massive success.
I optimized for this style setup about a year into the pandemic, but using a Beyerdynamic MX300 wired gaming headset. The headset is closed-back, so to get voice feedback ("sidetone") I use an inexpensive Behringer XENYX USB302 mixer. It allows for adjusting the mic/audio mix going to my headphones, and also is a USB audio interface.
This setup is as minimal as I was able to get it: no big booms on my desk to move around, microphones blocking my video, etc. Yeah, I look like a pilot on calls, but the audio quality is amazing. Also, the mic being close to me blocks background noise, and isolates it from my desk. Sometimes my colleagues with podcaster-style mics have issues with mechanical transmission from their desk setups, while I have none.
People often comment — even to this day — about my audio quality. I talk to people all day, being in sales, and it makes a huge difference in my presence and professionalism. Absolutely worth every penny I spent.
As a side note, I also use my iPhone as my webcam (continuity cam I think it's called) along with a couple Logitech lights on my monitor, and the overall quality of my digital presence often blows people away.
It surprises me how many people in sales, marketing and other external facing roles don't optimize their AV setup.
Honestly I'm sort of surprised that there isn't training about this given how much sales training people go through. Presentation is HUGE. A good mic, a proper camera, and even just minor consideration for lighting make anyone so much more credible, and pleasant to talk to.
> It surprises me how many people in sales, marketing and other external facing roles don't optimize their AV setup.
It's not that surprising, it's fairly technical and many don't want to deal with it (ask anyone if they know what XLR or phantom power is), another problem is there's so many different options that it often leads to choice paralysis and some people feel uncomfortable to ask for money to buy better equipment.
Myself and my team are all technical sales folks with engineering backgrounds, and we naturally optimize for this sort of thing — all of us have some form of “advanced” setup that’s been informed by each other’s investment.
On the other side, NONE of our account reps have anything remotely close. I can think of one or two times in the past few years when someone asked me about what tech I use. My company even has a home office budget benefit meant for exactly this sort of thing!
Unfortunately since it’s an active feature it requires power, meaning any wired headset will require a battery or other power source.
A wired headset plus my mixer gives me an opportunity to tinker and upgrade my setup as I wish, and is all USB powered to boot.
I have some rough plans to make a simple audio interface with built in sidetone for use as a portable setup, but haven’t had the time to turn it into a real product. Someday!
> This setup is as minimal as I was able to get it: no big booms on my desk to move around, microphones blocking my video, etc. Yeah, I look like a pilot on calls, but the audio quality is amazing. Also, the mic being close to me blocks background noise, and isolates it from my desk. Sometimes my colleagues with podcaster-style mics have issues with mechanical transmission from their desk setups, while I have none.
I kind of went the other direction here.
AT2020 condenser mic into a focusrite scarlett. Mounted on an adjustable boom that's clamped to the far right end of my desk with a shock mount and pop filter (so I can get the thing fully out of my way). Sound comes out some bookshelf speakers sitting below my monitor.
My monitor's raised up a bit on an arm so about 20% of it is above eye level for me with the webcam sitting on top of that. It's a solid few feet away from me, so the angle isn't really noticeable to anyone I'm on a call with. But the angle does mean that I can pull the microphone right in front of my face, just below my mouth so I'm speaking over it, and it's not blocking my mouth or any of my face. (Visually it's in front of my shirt and on the edge of the frame anyway.)
It already does a fairly good job of isolating my voice by virtue of being a cardiod mic inches from my face, but further from that I have it set up (in software) with a noise gate opened by the microphone _in my webcam_. When I'm talking to people I'm generally looking at them so I'm speaking towards the monitor. This sets it up so sound directed towards the monitor opens the mic, but other sound generally does not.
I couldn't find a pair of over-ear headphones I could comfortably wear for long periods of time--they'd all push on the arms of my glasses and end up really sore after a couple hours of calls in a day (even non-contiguous). Instead of trying to solve that, I just steered hard into making the open setup work and sound as well as I could.
As far as visuals--I have a couple of LED light panels for my photography that are set at 45 degrees to either side of my camera, with one adjusted a bit cool and one a bit warm. Picked it up from some time spent doing stage lighting--if you evenly light a scene, it looks flat. (Think a photo taken with an on-camera flash.) A slightly warm and slightly cool wash from different angles can be lit fairly brightly while maintaining the depth and texture.
Different approach but same goal and outcome: I spend a lot of my day talking to people and trying to convey information. It's to my benefit that I'm clearly heard and easily understood. And, besides the practical concerns, professionalism. Frankly, I think it's silly _not_ to invest (to some extent, anyway) in this. In the remote work world, a huge part of everyone's interactions with and perception of you is actually their interaction with and perception of your audio and video setup. You don't need to overdo it, but don't be _bad_ at it.
I'm now very careful to pick ceramic capacitors with enough headroom on their rated voltage as you lose a lot if you're close to the rated value. This curve is dependent on the different ceramic types as well (C0G, X7R, etc). Cheaper ceramics have a steeper rolloff.
For personal projects I am very careful to pick higher quality ceramics (X7R if I can) and use caps rated to 2-3x my operating voltage. Likely overkill, but I'm not optimizing for cost at volume.
[0] https://resources.altium.com/p/voltage-derating-ceramic-capa...