I am trying to use a Differential Op Amp to receive and transmit over a Differential Signalling Bus.
I am basing this on this excellent op amp tutorial.
The Bus I am using has has 2 lines, Low(v1) and High(v2) both either 2.5V or 0V. When v1 is at 2.5V, v2 should be 0V, when v2 is 0V v1 should be 2.5V.
To receive I am reading the output of the op-amp.
I need the output to be 5V (so I need the difference between v1 and v2 gained/amplified by 2x).
In what I've built, V- is the GND rail and V+ is 5V. R1=R3=33ohms R2=R4=15 ohms.
When I disconnect R4 from the V- rail, V2 seems to go high.
Can I have an NPN transistor switch R4 from V- to transmit?
Does this design really make sense or do I need multiple op-amps (1+ for receive, 1+ for transmitting)?
Should this design work for receiving?
Before building the rest of my receiver (the MCU to connect to Vout), I want to make sure that it'll work, but my multi-meter shows 3V or 4V (it varies each time I check), because the bus is running at 25khz which is probably faster than my auto-sensing multi-meter.
I am using a LM741 (NTE941M) op amp.