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Author Topic: How i read low voltage digital signal from arduino with digital input ?  (Read 935 times)
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Hello!I want read low voltage 1,8 volt signal (f=40KHz) with digital input pins.What hardware must connect with Arduino pin for amplifier the signal?Transistor?The arduino pin need 4-5 volt to understand high level "1".
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Yes, use a transistor, see attached schematic. I assume you don't need to measure the amplitude of the signal, just see whether it is there - otherwise you can't use a digital pin. The diode D is only needed if the input signal is coupled through a capacitor. The transistor can be any small signal NPN type. The resistor values are not critical, I suggest 10K for both of them. You can omit R2 if you enable the internal pullup resistor for that pin.


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Thanks.I have BC 547 is ok?I make the similar circuit with Mosfet but no work....the Vgs(min)=2volt i think....The signal inverting with this circuit?
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Yes, BC547 is OK. This circuit does invert the signal.
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