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I've pointed my photo diode at a 6 inch BW TV.
As the photo diode is looking at 12-15 lines I had to interpret, but the persistence of lines in a bright white area seems to be only about 100us before it's back to near enough the black level. I thought the persistence would be longer than that. - it's less than 2 lines!
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Dodgy Technology / Re: Nexus 5x - Nexus never again.
« Last post by Halcyon on Today at 09:20:55 pm »
Sure.

But that's like saying the cost of a service on a Maserati costs the same as a Great Wall off the showroom floor. Apples and oranges.
To me, while $300 is something I would have much rather spent on something else, it was a fraction of the cost of the device itself and a cost I can easily absorb in my budget. For $300, Samsung essentially replaced every component in the phone except for the motherboard, not bad.

I chose to buy the Samsung S8 after careful consideration. $250 phones simply didn't meet my desired specifications or requirements.
Except that the difference isn't that distinct. It's oranges and slightly bigger oranges, but commonly with less juice. A few years back you definitely had a point, but the advantage of high end phones over quality budget phones has steadily evaporated. It's remarkable that high end phones are even sold nowadays, though it seems that cultural factors play a fair role in that. Having an expensive phone or having the latest and greatest is a way to disginguish yourself in certain groups.

I guess we see things differently. For me, it's about security. Anyone with a laptop and a bit of knowledge can suck the data right out of those cheap phones without any dramas. Something I would rather not risk if for some reason it was lost or stolen. But it's not just that, it's the larger battery, it's the ability to still have a usable connection in remote areas well after other phones fail to even see a base station, it's the faster access to the LTE network, it's easy same-day service/repairs if I need it without voiding the warranty by doing it myself (and being able to keep all my data intact).

A cheap $250 Android handset doesn't even begin to compare against a later model Samsung, except that it's cheaper. It fails in every other way I can think of. Is $800+ a lot of money to spend on a phone? Of course it is, but it's something I use heavily every single day and I cannot afford to have it fail. Not to mention a significant portion of the cost is tax deductible (for me), so in reality, it costs me far less in the long run.

This is what works for me. Your mileage may differ.
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I'll bow out and try to learn something. Gonna definitely check out Jody and some of ^ those I haven't seen before. This is a great thread, already.

Mr.Packethead, good luck. I was envious until you described the job in more detail. Now it sounds way too much like work!
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Dodgy Technology / Re: Nexus 5x - Nexus never again.
« Last post by Mr. Scram on Today at 09:14:49 pm »
Don't laugh but I still own a "stupid" phone.
Made in 2006 from Nokia, it fell more than 10 times, charges one time a week and still works on the original battery for over a week before recharging and can't be hacked.
Somehow they should not call it phones anymore since people are not using them primarily as phones.
It should be named a "fragile tinypad with phone capability" :)
Feature phones can be hacked too. Especially the baseband chipset seems to be as vulnerable as those found in smartphones. There does seem to be much less attack surface in regards to the OS and saying they're safer doesn't seem unfair.

That being said, I've regularly contemplated going back to a feature phone or even to ditch the mobile phone completely.
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Time of flight sensors are pretty accurate and use I2C

Look at the VL53L1, there's an arduino library available for it too
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Beginners / Re: High voltage linear regulators.
« Last post by imo on Today at 09:09:08 pm »
The 723 requires maybe 3-4mA for itself, 50y back they used a 12V zener for the 723, the high-side transistors could be stacked up for almost any voltages/currents (as they are current driven out of the 723).
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I learned some welding 20 years ago at school (not certified), but after watching probably most of the welding channels on youtube and collecting some problems at hand that can be done by welding, a couple of weeks ago i bought a relatively modern 200A AC/DC pulsed TIG/MMA/Plasma machine with a 5 year warranty on the machine itself and a pedal. Chinese manufacturer, german brand distributor. Also bought the safety gear (jacket, gloves, auto darkening helmet, welding blanket) and exchanged the gas cooled torch against a flexible one (several types are compatible), plus a gas lens kit. Some quick connectors for the gas were useful, as the machine only has one inlet for pressurized air and argon. Price range for all of it roundabout 1400 Euro.

I already finished a few little things here and there, the learning curve is quite steep and it was fun to learn. For aluminum the pedal was really important to adjust the current while you go and not screw stuff up, blow holes into the material and control the puddle, the hotter the parts get the less current is needed to melt - or just pre-heat.

If you want to cut and weld containers we are talking about steel sheet metal and a bit square tubing, maybe working on a ladder on some distance away from the power. I don´t get why you would want TIG, as your job sounds right for MMA or MIG anyway - with MIG you could use shielded flux wire and therefore work without gas, as you do with stick. You can even work one-handed, which in this case is a huge advantage over TIG. Most TIG machines do come with MMA, but a MMA/Plasma combo is probably cheaper. If you already know the maximum thickness to weld, you might even get away with a lower amperage requirement (160A for up to 4mm?!).

I don´t know how you want to weld these together, but when running beads on sheet metal always take the shrinkage into account, otherwise it might deform drastically or simply crack. The grinder will still be your best friend, as you need to bevel thicker materials to really have penetration down to the root of a joint.

My advice for buying a machine:
- if you never want to weld aluminum, you can skip machines with AC completely, it will drop the price significantly
- check the inrush current to match your power supply (in my case i got a single phase 230V, slow 16A B-characteristic breaker, that works fine even under full load), the cheaper models have the tendency to pop the breaker, maybe you could use an inrush current limiter or have access to good three phase power
- check which duty cycle you get, a 20% rating means out of 10 minutes, you can operate it 2 minutes and need 8 minutes cooldown, the higher the better, may also mean it is more reliable in the lower ranges
- check for DINSE connectors (cylindrical with a notch) on the machine, or at least one that is useful, so you can replace the cable package with a longer one
- check minimum current setting as mentioned by BradC, should you want to work with finer gage sheet metal (rule of thumb for steel: 40A/1 mm for welding)

- for TIG you might want the amperage control next to the place you weld, so for working on a ladder you should consider a torch with control included in the torch
- a pulse machine helps controlling how much heat goes into the part, but the helmet should be able to work with it (helmet delay > maximum pulse off duration ... so you don´t flash yourself at the restart)

- the TIG torches are mostly compatible to the consumables you can find on ebay (for compatibility watch this: www.youtube.com/watch?v=3KroGM5e1dE)
- the plasma torches that come with it use pretty much standard consumables

- pressurized air supply should be sufficient (in my case 4.5 bar, 80 litres/minute)
- a 50A plasma cutter is rated for 12mm thick construction steel

for the actual job i´d say:
- practice various positions you will need to do (e.g. vertical up welding) with test pieces to find settings that work for you as much as you can before you start
- practice open root welding
- practice, practice, practice
- stay away from critical, potentially dangerous stuff, anything that people walk on or under

Really good channels for welding are ChuckE2009, weldingtipsandtricks, weld.com, the Fabrication series, This Old Tony and all i forgot. They all cover some aspects, but of course do not replace practice.


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Beginners / Re: High frequency capacitor selection
« Last post by imo on Today at 09:03:21 pm »
@ZeroResistance: better you define the required capacity (in nF/uF) at specific frequencies, max currents (Ip-p), voltages(Vp-p), and other params you are aware of, and the experts here may identify the proper caps for you easier.
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Thanks Alex.

FYI, for anyone else looking at this in the future, there's a doc here which gives a bit more analysis of relay contacts re low thermal:

https://www.mouser.com/pdfDocs/switching-low-offset-voltages-training.pdf

Alan
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EEVblog Specific / Re: EEVBlogAcademy
« Last post by Pete F on Today at 09:00:38 pm »
Thanks very much, I’ve seen a few of his videos and he does a good job. It’s probably a bit more basic than I was looking for though.

My background was in various areas of electronics at a trade/post-trade level, which is somewhat similar to these Blog Academy videos. Obviously we would go to much greater detail and somebody doesn’t watch a 10 minute video and expect to come out with the same knowledge as something that may have taken us a semester, but the point is both are relatively practical in their approach. I’d like to go back over a lot of that material, refresh and update my knowledge, plus drill down to greater detail if possible without losing the practical perspective.
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