Grumpy_Mike:
The brightness did not change.
How do you know? If you only looked at it then that is not good enough to make that statement. The brightness needs to be measured in order to estimate the life shortening that has occurred from over current.
- Because I know how it looks like, at first the color will detoriate, and then eventually the LED even will make "pop".
- Because 40mA to 70mA for 1/2 a second in my opinion won't really do much damage. These currents only start to do damage, when the LED has heated up already.
Grumpy_Mike:
There are countless examples including some I saw myself for commercial designs, which can be "questionable". Except Bang&Olufsen "component graves" designing/manufacturing consumer goods seems to be some kind of "black art".
Yes there are many designs that are engineered to a price rather than reliability but there are many many more that are not. A manufacturer is under the obligation to support a device for five years after he has ceased making it. Field returns are expensive epically late ones. I don't believe that nowadays any one designs a circuit to fail after a certain time.
Typically most PCBs using electrolytic capacitors will experience massive problems after about 20 years. Especially when the chips timing originally already is at the margin. The capacitors detoriate, and at some point of time, voltage levels won't be good anymore. Spurious errors will occur and soon, they will increase, at some point of time the whole PCB will fail. I did not make this up, I had one game console PCB, (which was new never used, but about 20 years old), it started up for a few minutes, but then errors occured, and after some hours, it did not start up at all anymore. And (cheap) electrolytics all over the PCB.
One Mitsubishi made VCR from 1986 actually had very good capacitors, still work like new.
Definitively there are special kinds of pushbuttons, which are specified for only 10,000 "push" operations. Where normally it's at least 100,000 times.
The designs are often bad, not neccessarily on purpose, but having totally superfluous components, as well too much heat developement. I don't know if they simply don't care, or if this is normal for some kind of goods. They all work fine but after some years, you can see first signs of problems developing.
LED circuits aren't so popular now for consumer goods except some smaller displays, but LED calculators were common some 2 decades ago. I never really saw resistor networks inside them, so they must have adapted the controller chip, somehow.
Maybe, Grumpy_Mike, you don't understand my point of talk.
It's that eventually, not many people really will use LEDs without resistors.
It is of course, bad. But I tried to explain, there are many examples of questionable design, which can be seen inside commercial goods. Not only the cheapest ones.
Bang&Olufsen for instance is a brand where you would expect, even after 20 years, that it still can be used, without problems, and that repairs are possible. You'd see it in the price tag...
My thought is that all this bad design really can't be stopped. Some hobby users actually never will design anything that is sold, but it seems to be normal (some kind of black art) to rely on questionable design.