This circuit for frequencies of 20 to 2 kHz was obtained in English documentation from 1966. The transistor can be any general purpose and powered by batteries.
Today we have more compact solutions. This is from a Radio Electronics magazine from October 1990....
This circuit is from an 80's documentation, making use of PUTs that are not currently common...
This circuit multiplies the input voltage by 3 and can work with up to 12 V input. The current is a few...