Maybe the Vsrc signal is not 2.0VDC and 4.15VDC. Maybe it is pulses of maybe 5.0V with Pulse-Width-Modulation (look it up in Google) where the duty-cycle of the pulses determines the average voltage.

You can increase the value of C4 to average the voltage of the pulses but since we don't know what is the frequency then we must guess on the value of the capacitor. If the value of the capacitor is too high then the switching from 2.0V to 4.15V and back will be slow.

You can increase the value of C4 to average the voltage of the pulses but since we don't know what is the frequency then we must guess on the value of the capacitor. If the value of the capacitor is too high then the switching from 2.0V to 4.15V and back will be slow.

Last edited: