With one transistor no. With two do a google image search for:-
schmitt trigger transistor circuit
Like:-
http://www.lammertbies.nl/comm/info/Schmitt-trigger.html
even a unijunction
So what do you know about a unijunction then, I last used them back in 1968, where I used a PUT programmable unijunction transistor. Mainly to make relaxation oscillators.