any one can suggest HOW I could supress reverse inductive spikes?!?!(is this the right term???) on this oscillator.. it runs great on lower voltages BUT when i supply it with 12-15VDC, it gets DEAD...
What exactly happens when you apply 12-15V .. oscillations stop or Q1 is killed?
You may try to add a resistor (100-470Ω) between the base of Q1 and transformer's winding ..
I think the oscillation stops..... Ive used 4.7uF tantalum and it burned after a few minutes .... then the circuit DIED....also the transistor heated so MUCH,,
is it OK too IF I shunt a diode in the colector-gnd winding??
As far as the 4.7µF cap is concerned, the best choice will be a bipolar cap .. if you don't have it, use electrolytic capacitor rated for at least 25V ..
Instead of a diode in parallel with the transformer's winding I would connect a 24V 1W zener diode in parallel with the power transistor - cathode to +V (emitter), anode to the collector ..