Comprimize of power supply voltage

cm961 · 13th June 2003, 08:17 PM

Hello,

I plan on building a supply which will power a bridged/paraelle LM3886T similiar to the one in the application note (National's AN-1192) which calls for a +/- 42V. Howevevr, I also want to power 4 individual GainClones using LM3875 or LM1875 chips. Now of course +/- 42V is too much for a GainClone. So I guess what I'm asking is whats considered the uppermost supply voltage that can be used in a GainClone?

Pete

platenspeler · 13th June 2003, 08:29 PM

Peter,

For the LM-1875 this is even lower than for the LM3875. The LM1875 has an absolute maximum (datasheet) of +/- 30 Volts DC. But I used a power transformer of -16.5 and +16.5 Volts AC which results in +/- 23 Volts DC after rectification.

The LM3875 has an absolute maximum rating of 84 Vdc rail-to-rail (+/- 42 Vdc), but most on this formum use lower values in order to connect speakers with lower impedance to their gainclone. I used a dual 22 Vac transformer of Plitron/Amplimo which provides +/- 31.1 Vdc after rectification.

Therefore, I do not think it is a good idea to share transformers for these different chips unless you want to put the bridgeclone on a lower supply voltage intentionally.

(project and Power Supply background on http://gainclone.platenspeler.com)

Maarten

Christer · 13th June 2003, 08:41 PM

You might also consider using the 3886 also for the Gainclones
and the problem will vanish.

cm961 · 16th June 2003, 08:35 PM

Cool, thanks for the help guys. I'll probably just use all LM3886, as its going in a car anyways.

Pete

13th June 2003, 08:17 PM	#1
cm961 diyAudio Member Join Date: Jun 2001 Location: Peterborough, Ontario	Comprimize of power supply voltage Hello, I plan on building a supply which will power a bridged/paraelle LM3886T similiar to the one in the application note (National's AN-1192) which calls for a +/- 42V. Howevevr, I also want to power 4 individual GainClones using LM3875 or LM1875 chips. Now of course +/- 42V is too much for a GainClone. So I guess what I'm asking is whats considered the uppermost supply voltage that can be used in a GainClone? Pete

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13th June 2003, 08:29 PM	#2
platenspeler diyAudio Member Join Date: Jan 2003 Location: Netherlands	Peter, For the LM-1875 this is even lower than for the LM3875. The LM1875 has an absolute maximum (datasheet) of +/- 30 Volts DC. But I used a power transformer of -16.5 and +16.5 Volts AC which results in +/- 23 Volts DC after rectification. The LM3875 has an absolute maximum rating of 84 Vdc rail-to-rail (+/- 42 Vdc), but most on this formum use lower values in order to connect speakers with lower impedance to their gainclone. I used a dual 22 Vac transformer of Plitron/Amplimo which provides +/- 31.1 Vdc after rectification. Therefore, I do not think it is a good idea to share transformers for these different chips unless you want to put the bridgeclone on a lower supply voltage intentionally. (project and Power Supply background on http://gainclone.platenspeler.com) Maarten

13th June 2003, 08:41 PM	#3
Christer diyAudio Member Join Date: Sep 2002 Location: Sweden	You might also consider using the 3886 also for the Gainclones and the problem will vanish.

16th June 2003, 08:35 PM	#4
cm961 diyAudio Member Join Date: Jun 2001 Location: Peterborough, Ontario	Cool, thanks for the help guys. I'll probably just use all LM3886, as its going in a car anyways. Pete

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