can we take it as a fact that some electronic equipment wears out faster if you're constantly turning it on and off, while it may last longer if you had just left it on the whole time?
if you think this is true, why do some components wear out while others seem to be able to take the on/ off operation?
and, finaly, judging from that, which catagory do you think an ultrasonic humidifier would fall into?
thanks for any experiences.
max
*Switches* wear out, and other mechanical things (although relays are a lot more reliable in general than switches). A light bulb will not last as long with many on-off cycles as compared to being left on until it burns out; the reason is that the inrush current mechanically stresses the filament each time.
There are certainly some components which degrade more quickly when left switched on permanently than if switched off for part of the time. Some components don't like the thermal cycling caused by being turned on and off many times. For most appliances, if I think I will not use it in the next hour or two, I switch it off. For the ultrasonic humidifier, I would do this, unless anyone has some experience specific to these devices to suggest otherwise.
Chris
can we theoretically deduce if the cycles would be bad for the humidifier (and i'm talking about short cycles, 5min on and 5min off)
if a light bulb doesn't do well with on off cycles, what are some other components that similarly act like this
and what are some components that last longer if turned off for part of the time, even if its very often.
thanks for the replys so far. max
I strongly suspect that laser diodes last longer if they are not on all of the time. If the driver circuit is well designed then I think that the act of turning them on or off doesn't hurt them much by comparison. Of course it is hard to generalise and it will depend a bit on how hot they get and whether the different materials used have well matched temperature coefficients of expansion etc.
The metal tracks of ICs slowly get damaged by current passing through them. This is called electromigration and is basically caused by the very high current density, i.e. the tracks are so thin that the electrons have to go very fast to carry normal currents. The fast electrons knock the metal atoms out of position, and eventually a break can form in the wire in the place where the current density is highest. This is not likely to be a problem in a well designed IC if the temperature is kept down. The chips are often designed to run for about 10 years continuously at the maximum rated temperature and if you can make sure that it runs maybe twenty degrees cooler then it would last pretty much forever. Still it is a possible wear-out mechanism.
Chris
Leave everything on all the time. I used to service 3000+ crts back in the day and we found that we would get calls first thing in the am when folks turned them on and then found that for the folks that never turned them off we had no problems, scientific results, no, but heck we stuck with it!
But sooner or later old computer equipment depreciates to the extent that the power to run it continually costs more money than the potential increase in reliability is worth. I wouldn't spend >$35 on power in order to power my old CRT monitor for a year, just to possibly increase the life expectancy by a couple of months, and I doubt that it would increase its life at all. I will very likely replace it before it stops working just like most consumers. I have always powered off my monitor when not in use and I have never had a monitor fail on me, though this is of course a small and statistically insignificant sample. There are some devices for which the reliability doesn't improve when it is left on continually, e.g. fans, probably laser diodes, and some others. There are also environmental advantages in switching off unused equipment - provided that it doesn't result in you having to buy new equipment in the event of failures!
Chris
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