5V buffer for lm3886?

jesserparker · 17th January 2007, 01:40 PM

i will be running my lm3886s off of a switching psu which also has 3V and 5V outputs. i was planning on using the 3V to seperately power LEDs and such, and i was wondering if anyone knew of a simple buffer that would be happy running off of a 5V supply?

Minion · 17th January 2007, 05:15 PM

There are many Opamps that you can use as a Unity Gain Buffer that can run off of Low Voltages.....

Like maybe a LT6202 or even the TL081....

You can even use some Transistors or Fets as a Buffer which will hapilly run at low Voltages...It would probably be better if your Supply can supply +/-5v so you don"t have to worry about Bias Voltages or DC Offset.....

Good luck

Nico Ras · 17th January 2007, 11:20 PM

Quote:

Originally posted by jesserparker
i will be running my lm3886s off of a switching psu which also has 3V and 5V outputs. i was planning on using the 3V to seperately power LEDs and such, and i was wondering if anyone knew of a simple buffer that would be happy running off of a 5V supply?

Not realy. remember that the buffer, even a TL072 will not swing to rails, in fact it will go to rail less 1 volt. If you have only 5V the maximum signal out of the buffer will only reach 3V p-p before severe gain compression. Overdriving this preamp will be to easy, you need more headroom.

My opinion only.

Ciao Nico

Minion · 19th January 2007, 05:38 PM

You can turn that 5v into 15v if you use a Voltage Tripler...

This should explain how to do it....

http://www.play-hookey.com/ac_theory...ltipliers.html

Just make sure that the 5v you are getting is has a LOT more current that you need because at Tripple the Voltage you will have about 25% the current available.....

Just a Thought....

halo0925 · 19th January 2007, 05:46 PM

Just build a simple shunt regulator, 1 to 1.2K ohm resitor and zener diode and some filtering.

jesserparker · 19th January 2007, 08:53 PM

i would totally do that, if i knew what that was.

Nordic · 19th January 2007, 08:56 PM

basicaly a voltage divider made up of a zener and resistor in series... to set voltage and current... not ideal, but better than nothing.

halo0925 · 19th January 2007, 10:52 PM

Nico Ras · 20th January 2007, 05:43 AM

Quote:

Originally posted by halo0925

hi Halo,

I think I am a little stupid. How does this work. If I am not mistaken, the zeners conduct like normal forward biased diodes I do not see how one derives the +15V and -15V from this circuit. Please explain.

Kind regards

Nico

Nordic · 20th January 2007, 05:52 AM

I agree... unless the 1k1 is dropping another 11V

17th January 2007, 01:40 PM	#1
jesserparker diyAudio Member Join Date: Mar 2003 Location: Ohio	5V buffer for lm3886? i will be running my lm3886s off of a switching psu which also has 3V and 5V outputs. i was planning on using the 3V to seperately power LEDs and such, and i was wondering if anyone knew of a simple buffer that would be happy running off of a 5V supply?

19th January 2007, 05:46 PM	#5
halo0925 diyAudio Member Join Date: Aug 2006	buffer PS Just build a simple shunt regulator, 1 to 1.2K ohm resitor and zener diode and some filtering.

19th January 2007, 10:52 PM	#8
halo0925 diyAudio Member Join Date: Aug 2006	shunt regulator

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17th January 2007, 05:15 PM	#2
Minion diyAudio Member Join Date: May 2006	There are many Opamps that you can use as a Unity Gain Buffer that can run off of Low Voltages..... Like maybe a LT6202 or even the TL081.... You can even use some Transistors or Fets as a Buffer which will hapilly run at low Voltages...It would probably be better if your Supply can supply +/-5v so you don"t have to worry about Bias Voltages or DC Offset..... Good luck

19th January 2007, 05:38 PM	#4
Minion diyAudio Member Join Date: May 2006	You can turn that 5v into 15v if you use a Voltage Tripler... This should explain how to do it.... http://www.play-hookey.com/ac_theory...ltipliers.html Just make sure that the 5v you are getting is has a LOT more current that you need because at Tripple the Voltage you will have about 25% the current available..... Just a Thought....

19th January 2007, 08:53 PM	#6
jesserparker diyAudio Member Join Date: Mar 2003 Location: Ohio	i would totally do that, if i knew what that was.

19th January 2007, 08:56 PM	#7
Nordic diyAudio Member Join Date: Sep 2005	basicaly a voltage divider made up of a zener and resistor in series... to set voltage and current... not ideal, but better than nothing.

20th January 2007, 05:52 AM	#10
Nordic diyAudio Member Join Date: Sep 2005	I agree... unless the 1k1 is dropping another 11V

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