Hello, the simplest is with 2 small transistors (2n2222a) 2 capacitors and 4 resistors .. I leave you an image that I took from a video where the diagram looks good, I hope you are lucky: D
http://www.mediafire.com/file/ccpamsmu7188f7h/sshot-2018-12-19-%255B21-44-44%255D.jpg/file