Pheetuz
Full Member level 3
Hi folks.
I am working on a project at the moment where i am comparing voltages around different areas of a circuit, these are then being fed into a PIC which compares them and decides if they are within parameters.
The pic is programmed and works correctly and the bulk of the circuit is designed, however I am having a problem with one aspect of the circuit, that being the potential divider.
The circuit thats voltages I am comparing runs at 24V which would destroy a PIC if I fed it straight into it, so I was going to use a 10:1 potential divider to step the voltage down, this is where the problem lies: I can compensate for the inaccuracies of the resistors by simply changing a few values within the code, however I cannot compensate for the change in resistance as the resistors heat up. (The voltage changes that I am trying to detect are within the mV range)
I am completely drawing blanks as to how to resolve this problem, other than just having to wait for the circuit to heat up everytime I want to use it, which is an option, but I would prefer to have a more temperature stable system, any ideas are much appreciated.
/Pete
I am working on a project at the moment where i am comparing voltages around different areas of a circuit, these are then being fed into a PIC which compares them and decides if they are within parameters.
The pic is programmed and works correctly and the bulk of the circuit is designed, however I am having a problem with one aspect of the circuit, that being the potential divider.
The circuit thats voltages I am comparing runs at 24V which would destroy a PIC if I fed it straight into it, so I was going to use a 10:1 potential divider to step the voltage down, this is where the problem lies: I can compensate for the inaccuracies of the resistors by simply changing a few values within the code, however I cannot compensate for the change in resistance as the resistors heat up. (The voltage changes that I am trying to detect are within the mV range)
I am completely drawing blanks as to how to resolve this problem, other than just having to wait for the circuit to heat up everytime I want to use it, which is an option, but I would prefer to have a more temperature stable system, any ideas are much appreciated.
/Pete