Author Topic: A switching power supply in an oscilloscope?  (Read 5736 times)

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Offline james_s

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Re: A switching power supply in an oscilloscope?
« Reply #25 on: March 12, 2019, 09:20:07 pm »
A lot of switchmode power bricks and wall warts are not terribly reliable either. I think I went through 3 of them (output capacitor failed) on my broadband router before I got fed up and dug out an old iron transformer type and used that. It has lasted longer than all of the switchmode adapters combined, which is worth the small efficiency penalty to me.
 
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Offline rsjsouza

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Re: A switching power supply in an oscilloscope?
« Reply #26 on: March 12, 2019, 10:29:40 pm »
A lot of switchmode power bricks and wall warts are not terribly reliable either. I think I went through 3 of them (output capacitor failed) on my broadband router before I got fed up and dug out an old iron transformer type and used that. It has lasted longer than all of the switchmode adapters combined, which is worth the small efficiency penalty to me.
Funny you mentioned that. I have gone through a few power supplies for the broadband modem and I also got fed up with them. In my case, I used a very nice switching power supply I had saved on my stash. I got them after people at work were scrapping zillions of old development kits that had become obsolete but featured top quality switching power bricks of different voltages (5V, 12V, 24V) and output currents (4, 5, 9A...).
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Offline tooki

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Re: A switching power supply in an oscilloscope?
« Reply #27 on: March 13, 2019, 01:41:51 am »
A lot of switchmode power bricks and wall warts are not terribly reliable either. I think I went through 3 of them (output capacitor failed) on my broadband router before I got fed up and dug out an old iron transformer type and used that. It has lasted longer than all of the switchmode adapters combined, which is worth the small efficiency penalty to me.
Yep, in my experience the switch mode wall warts aren't anywhere near as reliable. (In all fairness, the switch mode wall warts are largely quite reliable; it's just that linear wall warts are incredibly reliable.)
 

Online Zero999

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Re: A switching power supply in an oscilloscope?
« Reply #28 on: March 13, 2019, 08:54:29 am »
A lot of switchmode power bricks and wall warts are not terribly reliable either. I think I went through 3 of them (output capacitor failed) on my broadband router before I got fed up and dug out an old iron transformer type and used that. It has lasted longer than all of the switchmode adapters combined, which is worth the small efficiency penalty to me.
Yep, in my experience the switch mode wall warts aren't anywhere near as reliable. (In all fairness, the switch mode wall warts are largely quite reliable; it's just that linear wall warts are incredibly reliable.)
In fairness, some linear power supplies are also unreliable. Quite often the transformer is undersized and overheats. If you're lucky the thermal fuse blows, otherwise it can meltdown.
 

Offline james_s

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Re: A switching power supply in an oscilloscope?
« Reply #29 on: March 13, 2019, 07:51:14 pm »
I don't think I've ever had an iron transformer wall wart fail except in one case where a short circuit on the output blew an internal fuse.

Some of the switchmode wall warts are quite reliable too but many are not, particularly the extremely compact type.
 
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Offline tooki

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Re: A switching power supply in an oscilloscope?
« Reply #30 on: March 13, 2019, 09:01:01 pm »
Yep, in my experience the switch mode wall warts aren't anywhere near as reliable. (In all fairness, the switch mode wall warts are largely quite reliable; it's just that linear wall warts are incredibly reliable.)
In fairness, some linear power supplies are also unreliable. Quite often the transformer is undersized and overheats. If you're lucky the thermal fuse blows, otherwise it can meltdown.
I don’t think it’s fair to judge reliability based on a device run beyond its limits. An overloaded SMPS isn’t gonna last, either. I didn’t think it was necessary to specify that I’m talking about power supplies that are being run within their design specs. But with that constraint, I think it’s absolutely fair to say that a transformer power brick is going to outlive a switch mode one.
 
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Offline David Hess

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Re: A switching power supply in an oscilloscope?
« Reply #31 on: March 13, 2019, 11:35:58 pm »
There is just less to go wrong with a 50/60Hz transformer compared to a switching power supply so it takes more effort to make the later equally reliable.
 
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