oscilation

[jin2022]

hi friends,
this is an oscillator. at the beginning, Q1 is off, so does Q2.C1 is encharged through VCC—R1—speaker.and voltage of Q1 base increases. as Q1 base reach around 0.5v, Q1 starts on. so does Q2.and collector of Q2 feedbacks to Q1 base.it's positive feedback.Q1,Q2start saturation

and issue comes:will saturation hold on? if not, why? it is said C1will discharge, how it is done?

thx

 

[FvM]

Most likely staying on forever. Must me modified so that R1 current doesn't saturate the output. Also Q1 base and collector current should be limited to safe values.

 

[d123]

Hi,

Yes, I'd agree, it looks like the feedback between Q1 and Q2 is not going to make an oscillator. I'd assume that the more Q1 turns on, the more Q2 turns on. At best it might produce an old-fashioned air-raid warning sound (slowly rising then constant), if it were a buzzer.