Just so you know this is NOT an Ltspice question
So HP gave me schematic of Royer oscillator as test circuit for rebuilt LOPT transformers (which are just old TV flyback transformers optimized for HV power supplies). Anyhow the circuit works perfectly but I don't totally understand base drive so I can't use it for instructional material in good conscience until point of confusion is cleared up and HP is too busy for me to dare bug her with any of this until next week
So b4 I state question plz let me say this:
L6 is feedback winding
L7 & L5 are tapped primary winding
L8 is HV secondary
So here's problem that I just can't understand!
It looks to me like the negative end of feedback winding (L6) will be floating cuz B-E junction of BJT at negative end of L6 will be reverse biased? So how can positive end of L6 drive any current to bias its BJT?
To understand what I'm saying plz just think on this:
Say end of L6 on Q3 is positive (more than 0v with respect to ground and emitter of Q3) and also above silicon forward bias threshold (like 0.6v). So in order to supply bias current to Q3 base, other end of L6 needs ground reference but it's floating cuz it's negative which reverse biases b-e junction of Q4
Also putting external fast diodes across b-e junctions (with cathode to base and anode to ground) to give negative signal a ground reference seriously F's the performance of the circuit!
So I know I'm being stupid somewhere cuz it works great as drawn in real life and on simulator but I just don't get it and curiosity and need to move past it is stronger than pride at this point
Thanks an advance!
So HP gave me schematic of Royer oscillator as test circuit for rebuilt LOPT transformers (which are just old TV flyback transformers optimized for HV power supplies). Anyhow the circuit works perfectly but I don't totally understand base drive so I can't use it for instructional material in good conscience until point of confusion is cleared up and HP is too busy for me to dare bug her with any of this until next week
So b4 I state question plz let me say this:
L6 is feedback winding
L7 & L5 are tapped primary winding
L8 is HV secondary
So here's problem that I just can't understand!
It looks to me like the negative end of feedback winding (L6) will be floating cuz B-E junction of BJT at negative end of L6 will be reverse biased? So how can positive end of L6 drive any current to bias its BJT?
To understand what I'm saying plz just think on this:
Say end of L6 on Q3 is positive (more than 0v with respect to ground and emitter of Q3) and also above silicon forward bias threshold (like 0.6v). So in order to supply bias current to Q3 base, other end of L6 needs ground reference but it's floating cuz it's negative which reverse biases b-e junction of Q4
Also putting external fast diodes across b-e junctions (with cathode to base and anode to ground) to give negative signal a ground reference seriously F's the performance of the circuit!
So I know I'm being stupid somewhere cuz it works great as drawn in real life and on simulator but I just don't get it and curiosity and need to move past it is stronger than pride at this point
Thanks an advance!