LM1876 arduino mute

[dataplex]

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.

thanks!
-ú

 

[twest820]

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]

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]

thanks guys,

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

thanks,
ú

 

[DUG]

thanks guys,

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

thanks,
ú

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]

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,
ú

 

[tauro0221]

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

 

[twest820]

its just 5v to pin 6 and ground, right?

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

 

[dataplex]

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]

Hi,
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.

 

[dataplex]

hey tauro

im worried the mute pin might draw to much power from the arduino. the I/O pins of the arduino are limited to 40mA / 20mA reccommended!

and for some reason i cannot get the mute pin to work anyway, using a 5v battery to mute pins and ground. weird huh?

plus i need a latency free mute switch, and im not sure if the LM1876 mute pin works instantly... does anyone have experience with this chips feature?

 

[tauro0221]

Hi,
If you check the mute in the schematic Figure 6. LM1876 you can see that the mute goes to the base of a transistor so it would not required a lots current to enable or disable the mute using the output from the Arduino. I will use the output with no problem.

 

[madtecchy]

Fast muting/ unmuting will cause pops.. there must be a better way to get where you need to be .. Unfortunatley we do not know what that is so it makes it a little difficult to suggest any other potential options ..

Regards Mark

 

[tauro0221]

Hi,
Just to let you know that I am using a NANO micro to control the speakers output and also the mute of my LM3886 amplifier. Since the mute in the LM3886 it is negative and for isolation I am using a solid state relay LH1546. It worked with no noisy whatsoever.Just clean in the ON/OFF.

 

[dataplex]

hey, thanks for all the replies!

maybe i can switch the signal on/off before the LM1876 - if i where to use this IC :: http://semicon.njr.co.jp/eng/PDF/NJM2521_E.pdf

can someone help me draw a schematic that flips a low power signal on/off with my arduinos digital pins?

thanks,
úlfur

 

[Zero Cool]

try a 10k resistor between the arduino and the LM chips. that should sufficiently limit the current.
you could always use some small signal transistors as switches connected to the arduino to mute the chips. plenty of examples on the arduino web forums for that!

 

[counter culture]

and for some reason i cannot get the mute pin to work anyway, using a 5v battery to mute pins and ground. weird huh?

No, not weird, if you're using a single supply. In which case you need 1/2 the supply voltage +2.5V to achieve mute.

 

[tauro0221]

Hi,
Attached is an schematic on to do the input selection switching. This is an idea how to do it. It use 2 I/O pins from the Arduino micro.

 

[dataplex]

thanks again tauro

how does this PCB look to you? (its a bottom layer, thus inverted for printing!)

 

[tauro0221]

Hi,
At the beginning I was unable to follow the circuit since you over look that pin 1 it is the one with the square. You have to turn around the socket or leaving it like it is just cosmetic. Are you trying to switch audio no? I was thinking that you was trying to mute the LM1876. The NJM2521 what it does is to select one output from three inputs. I just want to verify that were are in the same track.