A simple level translator can be build with a 1kΩ resistor and a 4.7V zener diode connected in series with the Base of NPN transistor ..
- any voltage below 4.7V+0.65(Ube) ≈5.35V will "close" the NPN
- any voltage above 5.35V will "open" the NPN
So, if you connect Emitter to 0V and a 10kΩ resistor between Collector and 5V, the collector voltage will be TTL H for input<5.3 and TTL L for input>5.3 .. (if you need you can use an inverter, or another NPN, to change the otput to L for input<5.3V and H for input>5.3V) ..
Reagrds,
IanP