Power dissipation, especially in bar mode should be givenconsideration. For example, with a 5V supply and all LEDsprogrammed to 20mA the driver will dissipate over 600mW.In this case a 7.5? resistor in series with the LED supply willcut device heating in half. The negative end of the resistorshould be bypassed with a 2.2?F solid tantalum capacitor topin 2 of the LM3914.
My R1 is 660 making Iled=18mA (2x330 in series, because i dont have a 660 resistor) and R2 is 82 ohms (330 220 220 in parallel). The range of the leds is about 1.6 volts. Im powering it with a 9v wall thing
with a lm 3914
Power Dissipation (Note 6)Molded DIP (N) 1365 mWNote 6: The maximum junction temperature of the LM3914 is 100°C. Devices must be derated for operation at elevated temperatures. Junction to ambient thermalresistance is 55°C/W for the molded DIP (N package).
You can probably do it a lot more efficiently with your arduino.