I heard a story of a fishing boat in the eastern US that was "fighting a fish" for miles but could never get any traction. When another fisherman looked at their chart, he noted that they were dragged miles in a straight line towards Europe, and said "You caught a sub". The submariners don't care, they probably find it funny.
I built a computer vision device that used the top-down area of a penny as a calibration standard. Coins are useful, easy-to-get items that have relatively tight manufacturing tolerances.
Ever since coin clipping got out of hand in the 1700s most coins feature milled edges or edge inscriptions. They make the edges more resistant to wear and make any wear easy to spot.
Of course there's a limit to the precision you can get from coins, but considering the scale of their production and the account of handling they see they are surprisingly good
Our area measurement application did not require that tight a tolerance (we were estimating yield on broken material). If I needed that tight a tolerance, I could have gotten proof coins from the mint, or potentially switched to using a real calibration standard like a gauge block.
I have often, though I suspect not enough to make a significant difference to someone who is already OK with the slight variance between un-worn coins.
Depends on what your tolerances are. If you only need to be within a mm a coin is going to beat that by an order of magnitude.
We use a pack of cigarettes as a gauge for one of the jobs we do. Quick, (not so) cheap, and readily available. May have to standardize on a vape though in the near future.
Generally in order to ticket an itinerary, there needs to be at least one flight marketed (e.g. with the airline's flight number) by the "plating carrier" whose ticket stock the flights are issued on.
I can't buy an itinerary consisting of just BA238 on aa.com but I can buy AA6981 which is its codeshare. I can also buy an itinerary where I fly AA on BOS-JFK and connect to BA JFK-LHR, because there's at least one AA-marketed flight on the ticket.
The marketing carrier also can affect how the operating carrier gets paid -- codeshares can have different inventory which allows airlines that are partners but not super close to hold back inventory for themselves.
> I can also buy an itinerary where I fly AA on BOS-JFK and connect to BA JFK-LHR, because there's at least one AA-marketed flight on the ticket.
Dunno if that’s a requirement that AA has, but I’ve totally bought 100% Air France metal tickets that don’t even touch US soil on Delta because Delta sold the same itinerary for way less.
You bought them on their DL#### codeshare flight number (what [AA or DL]-marketed means in GP's comment).
I fly a lot of "Delta" flights that are entirely KLM or Republic metal, often buying the Republic flights with Delta points earned on the KLM flights. (NB: the Republic airplanes say “Delta” on the side, while the KLM ones say KLM.)
It depends on the component and the company/process. Laser trim time for thin film is a significant cost-driver, so if possible you want to aim for a specific value and reject or bin-sort the rest out. My company only makes 1% tolerance resistors by laser trimming.
Thin-film resistor design engineer here! It's dependent on value and geometry -- if you order a 0.5 ohm resistor the meters on our trimming lasers only go down to 20 mΩ and you're getting a 5% part at best.
And that's why the really precise resistors are so damn expensive. E.g. VPG makes a 10k 1/5W 0.001% tolerance ±0.2ppm/°C, but they're $116 each with a minimum order quantity of 25 on DigiKey (so $2900 minimum purchase). They've got a really expensive meter for their trimming setup!
I'm not as familiar with foil resistors, but if you apply the same rules as thin film I would expect that you could trim this with a normal meter (the ± is 0.1 ohms) and the major cost driver is laser trim time and the space cost of some extra geometry on the resistor to support the tight tolerance (i.e. more fine trim features than standard).
I believe Vishay's ±0.2ppm/°C TCR is a materials science process specific to one of the companies they own, so that is also a reason they can charge quite high prices.
If you don't need that kind of TCR (i.e. your part is not going to space) the price should go down considerably for a thin film NiCr resistor (5 ppm - 25 ppm). There is actually a lot more direct sales and custom design volume than I would have expected when I started in this industry, so what you see on Digi-Key is not the entire market.
As both a sound and electrical engineer I think most high end audio electronics is bullshit.
If you know what you're doing a 50 cent opamp will give you results that are beyond what a human could identify in a double-randomized blind test. Same goes for comparing two rusty pieces of wire against highly pure copper speaker cables.
For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense.
For audio applications 1% resistors are fine. You can use still affordable 0.1% in places where you truly care. Below that it is getting ridiculous, as the influence of harder to match things will take over. Things like speakers or the room they are placed in. How about the speed of sound changing with air temperature and humidity? You better have a room that has uniform and stabilized air temperature and humidity.
A big part of the audiophile game is about psychological impact and the joy of personalized optimization. I spent a lot of money on audio equipment and a lot of time on researching it myself. It is an interesting thing. But in the end it is also physics that are interpreted by your brain and I can't help but feel bad for people who need to (incoming hyperbole) turn every part of their setup into gold in order to be able to enjoy listening to their equipment as music passes through it.
> For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense.
Is there a reason why they don't just use digital audio everywhere and convert to analog as late as possible? Inside the speakers for example? I mean, digital audio is pretty much perfect. Why are analog audio signals still a thing? People actually pay thousands of dollars for magical analog audio cables and it boggles my mind.
Good question, this is what most modern studio engineers would do, especially given that more and more speakers (like the Neumann KH120 II) feature internal FIR filters so you can calibrate them using measurement microphones.
Many modern Studios run some form of digital audio network as well (Dante, Ravenna, etc) so you can go digital as early and close to the source as possible and do all the routing using network switches and some sort of managment software (e.g. Dante Domain Manager). So if you do that it makes sense to go digital all the way to the speakers and convert directly to analog there after running through a DSP that allows you to correct for the speakers position in the room.
Cables can matter. But more for mechanical reliability, good shielding and perfect handling after years of use than any other magical properties. If you want to run balanced audio signals at miniscule loss for a few thousand meters it turns out that you can just use CAT6 for that. These cable are made for far more challenging (speak: higher frequency) signals and they have a track record of working.
My speakers convert digital to analog. They have ethernet jacks in the back. Maybe you bought the wrong speakers?
Stepping back for a moment… you see digital interconnects in high-end pro audio gear, using systems like Dante. These systems are NOT simple. When you have multiple digital audio systems connected together, you have to worry about whether they are all running from the same clock, or whether you can convert from one clock to another. Systems like AES solved this by having “word clock” running on separate coax cables with BNC connectors.
If you look at consumer digital audio stuff, like Bluetooth speakers, you find all sorts of weird problems. It turns out that for cheap consumer gear, you get better quality audio from simple analog connections anyway.
If you want speakers with digital inputs, you also need to power those speakers. That uses up more power outlets.
Right and isn't it the case that good quality D/A-converters still cost much money. So if you want every speaker to have them, and you want many speakers to get an immersive sound then "digital loudspeakers" can become expensive?
There are a lot of different parts involved—D/A converters, crossover networks, and amplifiers. Back in the day, good D/A converters were expensive, but they have gotten really cheap. If you have amplifiers that are cheap enough, you can put them after the crossover network and save money on the crossover network. If you have D/A converters that are cheap enough, you can eliminate the crossover network entirely and do it in DSP.
At that point you are comparing the cost of one more channel of D/A against the cost of an electronic crossover. It’s super easy to just buy a D/A with more channels. If you get to completely eliminate an analog crossover network, maybe that’s a win in terms of BOM cost.
It can be. But standard Bluetooth connections for audio can be terrible. Streaming from the internet, that is digital, and there can be delays and gaps in the sound.
By "perfect" I just meant that digital audio perfectly reproduces the recorded analog signals. https://youtu.be/cIQ9IXSUzuM
I didn't mean to indirectly praise Bluetooth in my post. Bluetooth anything pretty much sucks. Bluetooth audio in particular is pretty bad and full of usability issues. It doesn't seem to have the bandwidth required since the audio gets transcoded to some lossy format.
I once set up an mpd music server on my local network and audio quality was perfect. However I encountered significant latency issues. Play and pause had a latency of one second which made it unusable. That was true even for uncompressed audio streams over the network.
I got bored before I was able to resolve the problem. Maybe the problem was my network. I should try it again now that I have a much higher performance router running OpenWRT which is capable of traffic shaping.
Not much reason to use aggressive compression when wires have many orders of magnitude more bandwidth than bluetooth. And inconsistent latency is also not an issue when you control the whole network & don't need to share it with anyone else.
> For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense.
It's hard to find XLR (or even TRS) balanced connectors on most non-professional (=TV studios, expensive conference room setups, DJs/clubs/similar venues) equipment.
Yeah, but I wonder why? Sure, a Extron DMP with 128 bit DSp processing and 8 channels of balanced in and 12 channels of balanced out would qualify as professional conference equipment. But at a cost of approx 2.8 grand it is cheaper per channel than most audiophile equipment you can find.
The truth is that we sound engineers who use that stuff for work often do not have the luxury of caring for things that don't matter to the process or the outcome.
Professional AV equipment is expensive because it needs to be reliable on top of sounding as if it wasn't there, one of those units described above was running without fault for 15 years 24/7 in a room that was 30°C each summer (and it still works). Meanwhile my brother bought a silver RCA connector that broke off after a year of use — tip stuck in the amp, guess who had to fix it..
Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays.
I think this is more of a cultural divide than anything, with tradition being a big part of it. In the olden days balanced I/O had to be done using specialized transformers. Unless you got really expensive well wound ones these could degrade your signal significantly — that might've contributed to a bad rep in audiophile circles. But today you can balance or unbalance electronically with indistinguishable fidelity and... ironically a lot of the analog "warmth" people love in old recordings came from the transformer on the inputs of old mixing desks.
There is really no reason to use unbalanced today other than being really pressed for money or running so short cables that it won't matter - and even then you could do better than RCA connectors.
> Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays.
Yeah but who outside of people already interested in DJing buys that kind of stuff. It just looks ugly, unlike your classic home theater setup.
Out of "looks decent (=passes the Spouse Acceptance Factor test)", "reasonably affordable" and "has decent quality", choose two... unless you got a partner accepting you literally putting up a 2m truss with lasers, movingheads and a strobe in your living room that could compete with a mid-range disco, and a 1.200W fogger on the ground. I'm lucky enough to have such a partner, but I'd say about 99% of people don't.
There's something to it that the equipment should look beautiful in your living room, Bang and Olofssen -style. Music is beautiful, equipment playing it should be too. Or at least it enhances the experience.
Yeah it is a cheap mobile usb interface. Beauty is not the name of the game there — which is why I used it to argue against balanced being a feature of expensive equipment.
Balanced outputs have nothing to do with the aesthetics of the object. And I choose option 4 — build it yourself — then it can be done cheap and look however decent, massive, invisible, ridiculous or whatever the aesthetical ven diagram between your second half and you looks like. And it can have balanced I/O if needed ; )
What about shunt resistors? I can pretty easily get a 1% 5mΩ resistor, but they don't look to me like they are constructed in the same way as a generic resistor.
A barebones recipe is a complete commodity on the Internet and aside from maybe some ratings you have no idea if you should make it or not. The life history on some sites can definitely go too far but mostly I appreciate some of the backstory about why they made certain choices in a recipe and what else they tried.
SEEKING WORK | BOSTON, MA and PROVIDENCE, RI | REMOTE POSSIBLE | PART TIME
Technologies: ASP.NET Core, JavaScript / TypeScript, React, Node, Postgres, DynamoDB, AWS are the most common
I'm a full-stack engineer and I've managed to carve out a niche solving problems in software that other programmers have not been able to. I'm looking for focused part-time work of about 3 - 6 months, though no project is too small.
I have extensive experience in manufacturing, specifically in both new-build and third-party IT systems (ERP, FIMS, smaller purpose-built systems) for manufacturing companies. I also have led projects for offering new manufacturing products using existing factory capabilities as a design engineer.
SEEKING WORK | BOSTON, MA and PROVIDENCE, RI | REMOTE POSSIBLE | PART TIME
Technologies: ASP.NET Core, JavaScript / TypeScript, React, Node, Postgres, DynamoDB, AWS are the most common
I'm a full-stack engineer and I've managed to carve out a niche solving problems in software that other programmers have not been able to. I'm looking for focused part-time work of about 3 - 6 months, though no project is too small.
I have extensive experience in manufacturing, specifically in both new-build and third-party IT systems (ERP, FIMS, smaller purpose-built systems) for manufacturing companies. I also have led projects for offering new manufacturing products using existing factory capabilities as a design engineer.
I believe the economics of VPN companies is that they have a quite inexpensive, commodity product which has a lot of churn. The ads get people to sign up for a month or two at any price, which pays for the cost of the ads.
Tom Scott’s video a few years ago helped, but some creators still seem to be saying or implying that using a VPN makes your browsing “safer,” which unless you have a very specific need for a certain kind of safety, is untrue. I wish VPN companies would audit the claims their partners are making about them, but there really isn’t an incentive to do so —- if their brand gets damaged irreparably they can release a new VPN under a different brand.
Nordvpn seemed like a decent choice for streaming bbc but I won’t use them because of a company advertises that hard it must be bad. I would never trust them for privacy they are too big
This happened to my grandmother during the end of her life. Most people don't realize that many blind people retain some sort of vision or light perception.
- If you write her letters or need to write anything on paper for her, buy some black roller-ball or gel pens from an office supply store, ideally the 1 mm stroke width ones. These were as good as the pens we got from the eye doctor.
- Libraries often have resources for the blind or hard of vision (large print books, audiobooks, audioplayers with analog controls). HN tends to go for technical solutions but it's really up to the person using the solutions what they are most comfortable with.
- Your local society for the blind has people who have been through this before, which is important both for your mother but for your mental health as a caretaker.
