My question concerns KORG guitar tuner TM-40. I would like to measure by the tuner frequencies from the microcontroller. (square signal) Question is what can handle an input of the Korg tuner? From wikipedia I found guitars can pick up even up to 10 Volts which would be ok for 5V atmega but wikipedia also says guitars usually gives no more than 1 Volt.
So the question is: Would be safe for my tuner to provide signal to the input of magnitude 5 Volts?