weird oscillator problem

I built an rf single stage transistor rf oscillator, tank cct using 15 turns on a ferrite toroid, connected to collector, with a single turn coupling link to the base. Powered by a 12 v transformer supply. It takes a few flicks of the off/on switch to power up. (Mystery no 1). Then I replaced the power supply with a 12v car jump-start battery. Refuses to power up. I bypassed the off/on power switch, and tried applying 12v to the 12v power rail manually with a lead connected to the 12v car jump-starter, repeatedly pressing the 12v lead to the cct board 12v rail. Nothing. Incidentally, I had also placed a capacitor across the 12 V supply, which killed the oscillations immediately. Got rid of the capacitor. Still with the car jump-starter, I tried manually pressing the NEGATIVE lead to the cct board 0v rail, and after a few presses IT STARTED! Back with the original power supply, I placed a CRO across the power supply to see if there was some strange glitch in the 12v supply when I switched it on. IT WOULD NOT START with the cro connected across the 12V rails! I am mystified. I don't guess anyone here might have a clue about this. Seems there is something in the original power supply that is critical to oscillations starting up.

by don1248
November 23, 2023

Also seems to depend on the manner of switching the power on.

by don1248
November 23, 2023

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