Load Current limiting

k1jroth · 19th November 2004, 10:15 AM

I`m building 2 channel amplifier to my subwoofer and
have a problem with current when amplifier is off and i turn it on.

I think load current is too much for my fuses.
Transformer is toroidal 230V 2x40 1200VA
and there is 144000uF capasitance.
input fuse is 10A slow and output fuses are 10A fast.

How can i limit loadcurrent that fuses won`t burn?

Please help!

quasi · 19th November 2004, 10:27 AM

Provided there are no problems with your setup it could be the in-rush that is blowing the fuses.

Try a soft start cct. Theres has been plenty of stuff here about that. Do a search for "soft start" or "soft turn on"

Cheers

cunningham · 20th November 2004, 06:20 AM

Your description is kinda vauge. Are the output fuses for the output transistors that are burning too? If this is the case, your circuit may not be balancing when initially powered up, or not biasing properly as the voltage builds. You might take a measurement of the initial current in outputs. As for the input, 1200 VA would have a lot of surge current and as Quasi pointed out, a soft start circuit would work there.

19th November 2004, 10:15 AM	#1
k1jroth diyAudio Member Join Date: Nov 2004 Location: tampere	Load Current limiting I`m building 2 channel amplifier to my subwoofer and have a problem with current when amplifier is off and i turn it on. I think load current is too much for my fuses. Transformer is toroidal 230V 2x40 1200VA and there is 144000uF capasitance. input fuse is 10A slow and output fuses are 10A fast. How can i limit loadcurrent that fuses won`t burn? Please help!

19th November 2004, 10:27 AM	#2
quasi diyAudio Member Join Date: Sep 2004 Location: Adelaide, Australia	Provided there are no problems with your setup it could be the in-rush that is blowing the fuses. Try a soft start cct. Theres has been plenty of stuff here about that. Do a search for "soft start" or "soft turn on" Cheers __________________ http://sites.google.com/site/quasisdiyaudiosite/

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20th November 2004, 06:20 AM	#3
cunningham diyAudio Member Join Date: Jun 2004 Location: Knoxville	Your description is kinda vauge. Are the output fuses for the output transistors that are burning too? If this is the case, your circuit may not be balancing when initially powered up, or not biasing properly as the voltage builds. You might take a measurement of the initial current in outputs. As for the input, 1200 VA would have a lot of surge current and as Quasi pointed out, a soft start circuit would work there.