14-06-2015, 09:43 PM
OK, I got my answer - 40W should do it. My thanks for that. 
What I should have explained but neglected to include in the OP was that I want a degree of bulb illumination because it's for a photo I want to take. I am preparing an instructable on assembling a series lamp limiter for beginners and it includes a number of photos of the limiter in use. One of the photos I want is showing a bulb partially illuminated indicating the device under test doesn't have any serious problems. Hopefully a 40W bulb will oblige with my 50mA component bridge.
As David said, that presentation on the hot and cold resistances was interesting Lawrence. It has given me the idea of perhaps creating a quick reference table to include in my instructable showing what sort of illumination one could expect with a current draw at 50mA increments up to 500mA for bulbs of 25W, 40W, 60W, 100W etc. I wonder if a beginner would find that a useful aid to selecting the bulb wattage for the device they want to test? I imagine I should be able to determine the answers using a simple device comprising a 0-500mA AC meter along with a fixed 470 ohm resistor in series with a 0-5000 ohm pot. If I plug that into the lamp limiter I should be able to vary the current from 44mA to 511mA.
Nick
What I should have explained but neglected to include in the OP was that I want a degree of bulb illumination because it's for a photo I want to take. I am preparing an instructable on assembling a series lamp limiter for beginners and it includes a number of photos of the limiter in use. One of the photos I want is showing a bulb partially illuminated indicating the device under test doesn't have any serious problems. Hopefully a 40W bulb will oblige with my 50mA component bridge.
As David said, that presentation on the hot and cold resistances was interesting Lawrence. It has given me the idea of perhaps creating a quick reference table to include in my instructable showing what sort of illumination one could expect with a current draw at 50mA increments up to 500mA for bulbs of 25W, 40W, 60W, 100W etc. I wonder if a beginner would find that a useful aid to selecting the bulb wattage for the device they want to test? I imagine I should be able to determine the answers using a simple device comprising a 0-500mA AC meter along with a fixed 470 ohm resistor in series with a 0-5000 ohm pot. If I plug that into the lamp limiter I should be able to vary the current from 44mA to 511mA.
Nick
