Hi all,
I have the attached circuit diagram. I wanted to know if there is any way of calculating the value of the pull down resistor. I don't want the relay to be driven on when the microcontroller is switched on.
My understanding was that if the output from the PIC is OV. Then the transistor is off because we have the 15K in parallel with the pull down connected to 0V. It's when we have a high impedance, I think that case the pull down cones into play. also there is a miller effect from collector to base of the transistor, which could be influenced by the hfe of the transistor I.e. noise. But the pull down discharges this capacitance to 0V.
So is there a way to calculate the pull down value? Thanks in advance.
I have the attached circuit diagram. I wanted to know if there is any way of calculating the value of the pull down resistor. I don't want the relay to be driven on when the microcontroller is switched on.
My understanding was that if the output from the PIC is OV. Then the transistor is off because we have the 15K in parallel with the pull down connected to 0V. It's when we have a high impedance, I think that case the pull down cones into play. also there is a miller effect from collector to base of the transistor, which could be influenced by the hfe of the transistor I.e. noise. But the pull down discharges this capacitance to 0V.
So is there a way to calculate the pull down value? Thanks in advance.