Victor wrote in asking the following... I added some links and responded best I could.
I came across your video about BJT when I was searching on youtube, it was really great! thanks for this!
I wonder whether you may help to explain the schematic please.
It was never explained to me what this schematic is, so my response is limited. Just looking at it, I guess it is probably some type of flip-flop.
The circuit is uploaded on here
may I ask why there is a diode please?
Probably to make sure current only flows in one direction depending on the voltage of the Trigger Input signal.
I search online and came across a term 'steer current'.
I don't know what "steer current" is.
I just don't understand why the trigger signal has to go through the capacitor,
Looks like they are coupling capacitors. Probably designed to filter out the DC component of the Trigger Input. Looks like the circuit only wants the edges of the trigger signal to pass through.
then two resistors to arrive to base of BJT,
Looks like the network of resistors are creating voltage dividers so that only one transistor is turned on at a time.
can it be done by removing R5, R8, C1, C2, D1, D2, and have two resistors connecting to the trigger signal, and each resistors go to a base of the BJTs please?
It is very rare to design a circuit with extra components for no reason. Without knowing what this circuit is supposed to do, I can't answer whether these components are extra. There is a reason they were designed in.