Trafo for LM4780?

moutoulos · 5th February 2006, 08:21 PM

I want designed stereo LM4780. The output current of LM4780 is 7A (+3.5A -3.5A).
Trafo 2x22vac 7A (+7A -7A 308VA) is good ?? or big??

moamps · 5th February 2006, 10:48 PM

It's just fine.

Regards,
Milan

moutoulos · 6th February 2006, 10:14 AM

Quote:

Originally posted by moamps
It's just fine.

Regards,
Milan

Thnks Milan !!.

Best Regards
Greg

I'm going to designed!!!!!!!!!!!!!!

peranders · 6th February 2006, 10:41 AM

In fact >100 VA will do if you are going to play music.

moutoulos · 6th February 2006, 01:25 PM

Quote:

Originally posted by peranders
In fact >100 VA will do if you are going to play music.

For each channel ? of LM4780
I want say 200VA ? for stereo LM4780 (2x40Wrms)

peranders · 6th February 2006, 02:57 PM

When it comes to choosing a transformer it's about the temperature inside. As long as it is under 105 deg C it's sufficient if also voltage drops and other things are under control. Think average power taken out of the transformer.

moamps · 6th February 2006, 03:26 PM

Quote:

Think average power taken out of the transformer.

Moutoulos said 2x40Wrms, meaning average.
Can you please elaborate the needed transformer's power rating for this amp if the temperature inside the chassis is 105degC?

peranders · 6th February 2006, 03:29 PM

2 x 40 watts continuous, then a 100 VA is too small but I said music....

The VA rating is determined of max temperature inside. Higher than 105 deg C the insulation will get damaged.

Notice also that the temperature also has to do with mounting and cooling.

moamps · 6th February 2006, 03:35 PM

Can you then please elaborate the needed transformer's power rating for this amp if the temperature inside the chassis is 100degC?

peranders · 6th February 2006, 04:04 PM

Then of course possible output from the transformer will be less.... 100 degs inside

5th February 2006, 08:21 PM	#1
moutoulos diyAudio Member Join Date: Sep 2005 Location: Patra	Trafo for LM4780? I want designed stereo LM4780. The output current of LM4780 is 7A (+3.5A -3.5A). Trafo 2x22vac 7A (+7A -7A 308VA) is good ?? or big??

6th February 2006, 10:41 AM	#4
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	In fact >100 VA will do if you are going to play music. __________________ /Per-Anders (my first name) or P-A as my friends call me

6th February 2006, 02:57 PM	#6
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	When it comes to choosing a transformer it's about the temperature inside. As long as it is under 105 deg C it's sufficient if also voltage drops and other things are under control. Think average power taken out of the transformer. __________________ /Per-Anders (my first name) or P-A as my friends call me

6th February 2006, 03:29 PM	#8
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	2 x 40 watts continuous, then a 100 VA is too small but I said music.... The VA rating is determined of max temperature inside. Higher than 105 deg C the insulation will get damaged. Notice also that the temperature also has to do with mounting and cooling. __________________ /Per-Anders (my first name) or P-A as my friends call me

6th February 2006, 04:04 PM	#10
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Then of course possible output from the transformer will be less.... 100 degs inside __________________ /Per-Anders (my first name) or P-A as my friends call me


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5th February 2006, 10:48 PM	#2
moamps diyAudio Member Join Date: Oct 2002 Location: Croatia	It's just fine. Regards, Milan

6th February 2006, 03:35 PM	#9
moamps diyAudio Member Join Date: Oct 2002 Location: Croatia	Can you then please elaborate the needed transformer's power rating for this amp if the temperature inside the chassis is 100degC?

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