We found this circuit in an English publication of 1976. It can be easily assembled by changing the components as we made. With it we can get 5 V with a current up to 100 mA for TTL logic power supply. The voltage input can be between 8 and 20 V and does not need to be regulated. R2 and R3 determine the accuracy of the 5 V output. The power transistor must be mounted on a heatsink.
