From entry level to mastery of triode waveform recognition

This is the current waveform of the transistor captured at startup. As you can see, at the moment of startup, the current through the transistor is very large. After the light turns on, the current becomes smaller. Let me ask you a question: why is the transistor current very large at startup? Why is there ripple modulation on the transistor current? Where does it come from?

This is also the waveform of the transistor collector current. Let me ask you a question: what is the difference between this waveform and the previous one? Why are there these differences?

To put it simply, the first waveform is when there is no preheating circuit; the second waveform is when there is a preheating circuit. When the lamp is just started, it is in a resonant state without breakdown, so the current is large. The ripple is caused by the high and low voltage at both ends of the electrolytic after rectification. [page]

Let's continue with the waveforms of the transistor: mainly the waveforms of the collector current and voltage!

This is the waveform of the transistor when the line voltage is too low!

The voltage waveform of the EB junction is added here

The rising and falling edges of this square wave are asymmetrical, indicating that a switch tube has a long on-time and is turned off too quickly. It may be underdriven. This current waveform seems to indicate that the working state of the transistor is not correct, and it is not fully working in the switching state, but seems to be in the amplification state.

This waveform is captured at the lowest line voltage and at the trough of the ripple! So it is severely deformed. We can understand that under such line voltage conditions, this waveform is acceptable! [page]

The following is a set of transistor error waveforms, which require re-debugging of circuit parameters!