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dataplex 12th January 2013 01:50 AM

LM1876 arduino mute
hey guys

i am waiting for my arduino MEGA to arrive in a few days.

i need to switch a bunch of LM1876's op amps on/off. they have mute pins that mute the signals passing through by receiving 2.5v.

so i figured i could use the arduino pins to switch an array of amps on/off.

however, my question is - do i need to put some kind of resistors inbetween or something to avoid drawing too much power/frying my arduino while muting 10+ LM1876's??

i should add, by default ALL AMPS WOULD BE MUTED AT THE SAME TIME - meaning id continuously be sending 5v through at least 10+ pins most of the time.

also, another question - i have never tried the LM1876's mute function - its instantaneous, right? im building a musical instrument, so if the mute function is delayed, its useless.


twest820 12th January 2013 04:48 AM

You can find the mute implementation in figure 6 of the LM1876 datasheet. The pin's input impedance is not specified but should be pretty high.

pra3718 12th January 2013 07:25 AM

Manual operated switch can be work for your specific requirement. Switch ON = 5V supply to mute pins and Switch OFF = 0V supply to mute pins and your all chips would turn in play mode.

dataplex 12th January 2013 12:18 PM

thanks guys,

is the mute function instantaneous? does it mute the IC right away?


DUG 12th January 2013 01:28 PM


Originally Posted by dataplex (
thanks guys,

is the mute function instantaneous? does it mute the IC right away?


Some datasheets offer this information...this one does not.

You will have to test the response time and adjust your arduino accordingly.

Let us know the results.

dataplex 12th January 2013 01:34 PM

has anybody seen a schematic where the mute function is applied?

i cannot for the life of me get the damn thing to mute the signals! with a split power supply, its just 5v to pin 6 and ground, right?

thanks for all your help guys,

tauro0221 12th January 2013 01:52 PM

One of the graphic in the datasheet showed the output versus the mute. Check it out.

twest820 12th January 2013 05:54 PM


Originally Posted by dataplex (
its just 5v to pin 6 and ground, right?

You can find the location of mute B in the datasheet too.

dataplex 12th January 2013 05:56 PM

yes, i know. i have actually been obsessively reading the datasheet for a week now. thanks though!

i think i might go for optocouplers switching the input signal on/off before the amp circuit. this just doesn't make any sense.

tauro0221 12th January 2013 07:11 PM

You can drive directly the mute using the output from the Arduino. The mute minimum/maximum voltage it is 2 to 5 volts. I do not see any problem. If the Arduino have D/A you can send an output of 2 volts. That is the beauty of using a micro.

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