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Topic: NJM2521 audio switch help (Read 1 time) previous topic - next topic


hey guys

i want to use this IC to switch a line level audio signal on/off, before it goes into a more powerful LM1876 amp :: http://semicon.njr.co.jp/eng/PDF/NJM2521_E.pdf

could anyone help me draw a simple schematic where the arduino digital pins do the switching? im worried about current draw, and don't really understand the test circuit demonstrated in the datasheet...

thank you!


Connect pins 2 and 4 to your arduino pins.
Page 2, look at the truth table (input control signal-output signal).

Pin 1, 3, and 5 are your analog inputs, use 10uf capacitor for signal coupling.


thanks for the reply!

i would be using pin 4 only for a stereo signal, right? mono signal and i would use pin one and pin 8 for ground?

like so:

(PCB is mirrored for printing)


This type of chip is usually used for "input selection"... AM/FM/TAPE/PHONO, that kind of thing. 

Maybe I'm missing something but why do you need to switch the signal lines on/off going to your amp? 
If you only have one source, why don't you just connect your signal lines directly and put an on/off power switch to your amp.


Jan 14, 2013, 07:55 pm Last Edit: Jan 14, 2013, 08:40 pm by dataplex Reason: 1
because this PCB is a part of a musical instrument, where each channel is one note, controlled by a keyboard. there will be 12 stereo amp chips, giving me 24 notes to play with.

thats why i need to be able to turn the channels on/off very rapidly, through a digital interface (the arduino)!

updated pcb with ground fill ::

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