I also need this, not with blinking, but numerically.
But maybe it can be made easier:
We can throw away the first digit, the hundreds (sure we can realize if we are below 100 or above 200 BMP) so we need only turn on the two LEDs of the two final numbers (tens and units).
Would have two potential problems, easy to solve:
• When the two numbers are repeated (66 or 99 BPM for example) it is enough to light one led (6 or 9).
• We will not be able to see specifically which of the numbers is tens and which is the units:
If the situation were static would be a problem, but keep in mind that by rotating the knob, the number is changing, and we will be able to appreciate perfectly the tens remains stationary while the unit moves.
Also would look pretty cool.
* If is needed to see the hundreds, we can use the 10 for under 100, 11 to over 100, and 12 for upper 200. (Obviously we are using only the last digit.)