in this circuit (link to article), what is the 47k resistor to ground (R2) for?
I simulated the circuit and noticed that without the resistor, there are negative spikes across the transistor's base-emitter at every negative-going edge of the input signal. Why?
R1-C1 is basically an edge detector, correct? But it also removes DC bias such that the 12V signal becomes centered around 0V (between 6...-6 V) The reverse-biased B-E junction looks like an open circuit . Is the purpose of the 47k to simply conduct the reverse current of the diode away from the transistor?
I simulated the circuit and noticed that without the resistor, there are negative spikes across the transistor's base-emitter at every negative-going edge of the input signal. Why?
R1-C1 is basically an edge detector, correct? But it also removes DC bias such that the 12V signal becomes centered around 0V (between 6...-6 V) The reverse-biased B-E junction looks like an open circuit . Is the purpose of the 47k to simply conduct the reverse current of the diode away from the transistor?