What I'm trying to do is loop the voltage response of a LM3914. Basically, I'm going to use one LM3914 to light up one LED for every 1000RPMs (already worked out the tach signal->voltage conversion), this is easy. What I'd additionally want, is a second LM3914 to light one LED for every 100RPMs, and start over every 1000RPMs.
So far, I figure I'd want pin 4 (set input for low end of range), to be tied to pin 6 (high high of input range), and to 7 (regulated output, 1.25V more than pin 8), and have the input at pin 8 jump everytime a new LED lights up from the LM3914 driving the 1000RPM increment LED array. The jump in voltage at pin 8 will shift the low end and high end of the range upward.
The only question is, what's the best way to step up the voltage at pin 8 in steps whenever a new LED on the other LM3914 lights up?
This seems like a nice enough display manner (same data, less total number of LEDs needed), that I figure at least somebody has done it before.
So far, I figure I'd want pin 4 (set input for low end of range), to be tied to pin 6 (high high of input range), and to 7 (regulated output, 1.25V more than pin 8), and have the input at pin 8 jump everytime a new LED lights up from the LM3914 driving the 1000RPM increment LED array. The jump in voltage at pin 8 will shift the low end and high end of the range upward.
The only question is, what's the best way to step up the voltage at pin 8 in steps whenever a new LED on the other LM3914 lights up?
This seems like a nice enough display manner (same data, less total number of LEDs needed), that I figure at least somebody has done it before.