This circuit is from an old American documentation and its use in motorcycles with 12 V is suggested to power 6V radios. The transistor can be the BD136 and BC548.
This sonic control circuit for a small robot turtle was obtained in an American documentation from 1967....
This circuit was found in documentation from the 70s. The transistors are from that time, but the...
These days the unijunction transistor (UJT) is not common, but IF you have one you can mount this...