Electronics > Beginners

LM317AHVT and Heatsink

<< < (17/17)

David Hess:

--- Quote from: mike_mike on December 15, 2019, 04:50:17 pm ---Can you please also have a look at the below reply and clarify the answer ?

--- Quote from: mike_mike on December 15, 2019, 09:53:01 am ---If I will make a higher current power supply, for example 10A (with more power transistors and a bigger transformer), then the power supply behavior will remain the same as described in this reply ?
--- End quote ---

--- End quote ---

It all depends on the current level and voltage across the LM317.

mike_mike:
This means that the output voltage is possible to rise when disconnecting the power supply from 230V mains, if the load is 9A, although the voltage didn't rise when the laod was 3A ?

David Hess:

--- Quote from: mike_mike on December 15, 2019, 07:55:03 pm ---This means that the output voltage is possible to rise when disconnecting the power supply from 230V mains, if the load is 9A, although the voltage didn't rise when the laod was 3A ?
--- End quote ---

Yes, that is possible.  When the AC input is disconnected, the input DC voltage to the regulator falls gradually.  As it falls, the current limit increases so the output current increases while the input voltage is falling.

xavier60:
And of course the output voltage will not rise above its setting.

David Hess:

--- Quote from: xavier60 on December 15, 2019, 08:27:10 pm ---And of course the output voltage will not rise above its setting.
--- End quote ---

It should not but some power supply designs have flaws.  A bare LM317 will not have a problem.

Sometimes failsafe circuits are added which clamp the drive to the output transistor during power up and power down.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod