Sawtooth generator with Programmable UJT

A not so well know semiconductor with the name PUT ( Programmable Unijunction Transistor ) has some interresting application. I build a sawtooth generator with a PUT. Of course not a build one but a build one from a PNP and an NPN transtistor.
I used a schematic from 'Inleiding tot de industriele elektronica' by r. de vos et all. ( 1978 ) with the PUT build from the named transistors. If one only uses a resistor and a capacitor a not liniair sawtooth is obtained. This is visible in the scope pictures. If you use a current source, which I build from a PNP transistor and a red LED the sawtooth is liniair.
I used an old power supply from the scrap yard from Fugro. A nice company in the Netherland where good equipment is used as can be seen on the power supply. Delta Electronics the best power supplies money can buy.