Limiting Inrush??

[Deltat]

Will the following circuit work to limit the inrush current from my 625VA transformer?

Kurt

 

[ifrythings]

The circuit will help with the inrush of current but why not just use a NTC?

 

[edl]

The circuit will help with the inrush of current but why not just use a NTC?

Because it haven't got time to getting colder when you reswitch the amp fast (or in case of a short blackout), and the toroidal transformer will kick the fuse because of the inrush current. Some manufacturers using NTC for this purpouse, but it's a slightly incorrect solution.

Best regards,

 

[Deltat]

i really wanted to go with an NTC but im also affraid that since this is going to power a switching amp that it may not ever really get hot and lower its resistance.

 

[richie00boy]

Yes both good points. NTC are no good IMO. Your circuit is good, I would use a bigger amount of reistance though. Try it and see, it's easy enough to change the resistor.

 

[edl]

Here the AC-mains is 230V, and I'm using 47ohm/20-25W wirewound resistor. Anyway many amplifier-factory using this value.
On the margin: yes, your circut will work, as Richie said.

 

[Deltat]

I haven no delay circuitry, will what ever delay there is on the AC/DC conterter board be enough?

 

[peranders]

By this you mean

If you don't have any problems with the inrush current, then you don't have a problem.

 

[AndrewT]

Hi,
try using a much smaller fuse once you have it up and running.
Aim for T6A or T8A. It might work with T5A if you up the resistor to 15r or 22r.

You want that mains fuse as small as possible to provide effective protection.

 

[testlab]

Check this out http://www.edn.com/article/CA198898.html

 

[Deltat]

By this you mean

If you don't have any problems with the inrush current, then you don't have a problem.

Well right now i dont have a relay in there and i have a big issue with inrush. Lights dim and even my UPS beeps.

 

[Samuel Jayaraj]

You could try this one:http://www.diyaudio.com/forums/showthread.php?s=&threadid=6654&highlight=speaker+protection