I'm converting an old console radio into a bluetooth stereo amp for a dear friend's brother in law. I'm ditching the tube guts and putting in a Bluetooth-equipped stereo board. Thing is, the LEDs that the board will power just aren't up to the task of lighting up the radio dial -- it's got to be an incandescent bulb. For reference - one of my builds. Scroll to near the end to see what I'm talking about re: lighting the dial: https://www.dropbox.com/sh/ylepfjvkqi2z6ti/AABBfSBQ1C5ZtgZYTB0_rm1Da?dl=0 So -- help me do this safely and check my math re: power resistor needed to safely lower the voltage and use a #47 bulb to backlight the dial. I really want this thing to be SAFE and dependable. The wall wart for the bluetooth board puts out 19vdc. I'm going to use a DPDT switch to connect hot/ground to 1) the BT board and 2) the bulb circuit. #47 bulb draws .15A of current. The Bulb circuit is: 19v+ --> resistor --> Bulb --> 19v neutral. I figure that a 10W (ceramic white block) resistor ought to be just fine. 75 ohm resistor gives me about 7vdc to the bulb, a voltage drop across the resistor of ~12vdc. Using Ohm's law to calculate the power dissipation of a 75 ohm resistor dropping 12v, P = V(squared) ÷ R. So, 12v squared = 144 / 75 ohms = 1.92 watts power dissipation. So -- at five times the dissipation, even though the 10W resistor the resistor gets warm/hot to the touch, it should be fine/safe in this circuit? Is there anything that I'm missing? Many thanks.