The voltage comparator used in this application is the NCX2220 from NXP. What this circuit does is transform a 3 V logic level signal into a 5 V logic level signal. The circuit can be used in an interface shield with TTL logic for microcontrollers.

The voltage comparator used in this application is the NCX2220 from NXP. What this circuit does is transform a 3 V logic level signal into a 5 V logic level signal. The circuit can be used in an interface shield with TTL logic for microcontrollers.