Light bulb current-voltage characteristics

Discussion in 'General Electronics Chat' started by someonesdad, Aug 8, 2009.

  1. someonesdad

    Thread Starter Senior Member

    Jul 7, 2009
    I was looking for something else and came across these measurements I did a few years ago. The instruments weren't in calibration (and still aren't), but I trust them within a few percent.

    The fitted model might be useful to those who want to estimate the resistance of an incandescent lamp at a certain current. Some day I'll also measure the usual 60, 75, and 100 W bulbs laying around the house. They can make useful (albeit nonlinear) dummy loads.

    I did the spreadsheet in Open Office. It has a nice feature in the graph -- you can click on the graph line and tell it to fit a curve to it via linear regression and to put the equation and correlation coefficient on the graph. I haven't used Excel in years; you could do linear regression in Excel, but it was more of a pain if I remember correctly. The curves available to fit are linear, log, exponential, and power. This plot looked about like a square root to me, so I picked power.
    Last edited: Aug 8, 2009