Power xformer for chip amp

Jim Karr · 15th November 2004, 08:18 PM

I am planning on building one of BrianGT's LM4780 chipamps when I gather all the necessary items to start... I have in my pile of old transformers a unit with secondary winding providing 37 vAC on each side of a center tap.

I realize this will give me about 52 VDC after rectification. My question is this: Will this overdrive the 4780 chip?
National's datasheet shows maximum of 84 volts, but all their circuits are designed at 35V plus and minus. Will my xformer work?

Tim__x · 15th November 2004, 08:20 PM

52+52=104

It'll blow your chipamp.

Stocker · 15th November 2004, 11:17 PM

So quick to give the big "XXX"!

Regulate it down to a safe voltage if you don't mind the heat generated by the regulators (and the wasted power)

If you don't want to regulate the power supply, rewind the transformer for the appropirate voltages. In this case, that should be, UNwind for appropriate voltages! It usually is NOT all that difficult, but quite intimidating nonetheless.

Tim__x · 16th November 2004, 12:05 AM

I didn't say it was impossible, I just said that as is, it will blow that chip.

15th November 2004, 08:18 PM	#1
Jim Karr diyAudio Member Join Date: May 2004 Location: Southwest Michigan	Power xformer for chip amp I am planning on building one of BrianGT's LM4780 chipamps when I gather all the necessary items to start... I have in my pile of old transformers a unit with secondary winding providing 37 vAC on each side of a center tap. I realize this will give me about 52 VDC after rectification. My question is this: Will this overdrive the 4780 chip? National's datasheet shows maximum of 84 volts, but all their circuits are designed at 35V plus and minus. Will my xformer work?

15th November 2004, 11:17 PM	#3
Stocker diyAudio Member Join Date: Dec 2003 Location: Austin	So quick to give the big "XXX"! Regulate it down to a safe voltage if you don't mind the heat generated by the regulators (and the wasted power) If you don't want to regulate the power supply, rewind the transformer for the appropirate voltages. In this case, that should be, UNwind for appropriate voltages! It usually is NOT all that difficult, but quite intimidating nonetheless. __________________ Jesus loves you.

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15th November 2004, 08:20 PM	#2
Tim__x diyAudio Member Join Date: Jun 2004 Location: Edmonton area, Alberta	52+52=104 It'll blow your chipamp.

16th November 2004, 12:05 AM	#4
Tim__x diyAudio Member Join Date: Jun 2004 Location: Edmonton area, Alberta	I didn't say it was impossible, I just said that as is, it will blow that chip.

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