Caroline Joy Barnhart
Your Kit must’ve had those “high quality” Radio Scrap components. 😆
My guess is you got one of the ITT2222 transistors. They made their plastic packaged version of the 2N2222 so that it did *not* conform to the standard E B C of the PN2222 or MPS2222. They were unpopular because they did not conform so Radio Shack’s ” 15 Assorted NPN” (or something named like that) package of transistors often had such oddball parts in them. I built a headphone amp and used these ITT2222 transistors connected up incorrectly, and they worked for more than a year before I found my mistake. Once I replaced them with the correct PN2222 transistors the headphone amplifier became louder and more sensitive. I stopped using those assorted parts packs from Radio Scrap.
So you connected it up with the emitter and collector swapped. With the voltage well above 5V max – like a 9V battery – the emitter to base junction goes into avalanche mode and the transistor turns into a relaxation oscillator. All you need is the capacitor in parallel to charge up and discharge at audio frequencies just like a neon light bulb. 🤷
