Trevor Rymell
Member
Dear All
I'm pushing my luck but can anyone advise me voltage dividing networks?
I am using an LM3914 to drive a 10-segment LED bar graph. It's very simple to connect up and if I put virtually any size of variable resistor to vary the 0-5v signal input voltage, the bar graph lights up, up and down as it should. No problem.
What I would like to do is replace the variable with a set of 10 fixed resistors.
My question is, is there a standard way to calculate the fixed resisitor values or is it done by simply measuring the value across the pot one step at a time as each segment lights up?
I don't know much about how the LM3914 works although I have the datasheet for the IC. What seems to happen is that it takes the maximum value of whatever variable resistor it's connected to and divides this up into more or less 10 equal steps. So if I use a 500 ohm pot, I get roughly 40 ohm steps between each segment lighting up. If I use a 50 ohm, the steps are about 4 or 5 ohms.
I'd be very gateful if anyone can advise.
Regards
Trevor
I'm pushing my luck but can anyone advise me voltage dividing networks?
I am using an LM3914 to drive a 10-segment LED bar graph. It's very simple to connect up and if I put virtually any size of variable resistor to vary the 0-5v signal input voltage, the bar graph lights up, up and down as it should. No problem.
What I would like to do is replace the variable with a set of 10 fixed resistors.
My question is, is there a standard way to calculate the fixed resisitor values or is it done by simply measuring the value across the pot one step at a time as each segment lights up?
I don't know much about how the LM3914 works although I have the datasheet for the IC. What seems to happen is that it takes the maximum value of whatever variable resistor it's connected to and divides this up into more or less 10 equal steps. So if I use a 500 ohm pot, I get roughly 40 ohm steps between each segment lighting up. If I use a 50 ohm, the steps are about 4 or 5 ohms.
I'd be very gateful if anyone can advise.
Regards
Trevor