Need 2nd opinion on Wiring diagram.. proximity - isolation - lpt.

[Doddy]

I am not sure this is right. The UC300 uses 5V logic, not 3.3V. Pin 14 of the HC14 is directly connected to pin 26 of the IDC connector #5 where the 5V output is (I just measured). Why would there be such weird voltage divider on the input? Also, the manual clearly says: "All output pins are TTL level with 0/5Volts output Voltage levels and an absolute maximum of +-20mAmps current per output channel. All inputs are TTL compatible and accept 0/5Volts Voltage levels."

Actually, for once I might agree with you - perhaps a half-arsed memory of mine of an aborted project to spin a replacement motherboard for the UC300 daughterboard with onboard ruggedised interfaces - and it describes the interface between the 5V motherboard and the 3.3V daughter card.

Yes, OP, ignore my previous senile ramblings.

EDIT: That's helped me to find the old project under Eagle, completely irrelevant for this thread, but for closure for myself....



That's the equivalent circuit for the daughter-card to motherboard interfaces on the UC300 (in case anyone else wants to ruggedise the UC300)