Thank you for your response. I draw a current flow with it, but i'm not sure.I'll take a shot at it. When power is applied, current flow through R2 & R3 into the base of T1 starts to turn it on. The collector of T1 goes low and current flows in the transformer primary winding. The aux winding is phased such that feedback through C2 turns T1 on harder. When the transformer saturates, the feedback collapses and the junction of R2/R3 is driven negative, turning T1 off. After the transformer field totally collapses, T1 is again turned partially on via the current from the supply through R2/R3 and the cycle repeats.