This circuit from Popular Electronics powers a small speaker. The transistor can be of general use and the capacitors can be altered to change the sound generated.
This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time....
This old oscillator using germanium transistors has a high impedance headphone as inductor to...
This preamp with several inputs using germanium transistors from the time was found in Japanese...