hello i have purchased the Velleman K8055 USB experiment interface board… and i was wondering what the purpose of the IC1: TLV274IN and IC2: ULN2803 in the board was???
Thank You
The main purpose of those components is to act as level shifters and to protect the microcontroller IC3 from direct access from external circuit voltages higher than the +5V power supply. The IC1 acts also as an input voltage amplifier by selecting proper value for R8 and R9.