Interesting results with a different 12V bulb. These ones seem to measure about 0.1ohms cold, and about 1.5ohms hot. Pretty close to the 1/15 quoted elsewhere.

EXCEPT something weird: The resistance nearly immediately after turning off *climbs* from about 1ohm to about 1.5 after about a second, then falls to about .3ohms after about 3 seconds... and eventually back to 0.1.

What?!

Inductance, maybe?

So, I stopped measuring resistance, and instead measure current... through the bulb, when it's switched Off.

And sure-enough, my meter gives around -1 to -2uA initially, then decays to -0uA in about one second. It takes another 2 seconds for it to read 0uA (without a minus-sign).)

[side-note: interesting plausibly-useful tool for the future: apparently when the meter's display is not precise enough to show a tiny non-zero measurement, it may still have enough measurement precision to at least display the minus-sign... That could be handy!]

So... it would seem a tiny current seems to be interfering with my just-turned-off resistance-measurement.

It could be inductance... Maybe even in my meter-leads and-or the wiring to the bulb... Though, If I understand correctly, the fact it's negative suggests it's coming from the bulb's filament.

But... something even weirder: When I allowed the bulb to cool, then turned it on only briefly, then ran the measurement, I got -4uA! 

This, I first figured was due to my *really wonky* Turn-off-then-touch-probe test-setup... Maybe it was initially -4uA each time, but I wasn't touching the probe fast enough to see...

But those larger currents didn't seem to take any longer to drop to -0. Infact, the display-update rate had it drop straight from -4uA to -1uA in what seemed one measurement time, just as it did in dropping from -2uA to -1uA, before.

Also... I tried being quicker with the turn-off-then-touch procedure, while having a longer on time... and did not see -3 or -4uA.

Repeat: for longer "on" times, I was getting up to -2uA. For shorter on-times I saw -3 and -4uA. 

This ain't inductance...

Then I remembered @Starhawk made mention of thermocouples... And, well, there are different metals involved. The difference between the filament and support-metal inside the bulb can't be responsible since it's symmetrical. But, the base is brass, and the nub isn't.

And That might just explain it... A short on time would result in a greater temperature *difference* between the inner-bulb-metals and the base. A longer on time would allow the base to heat up with the inner metals... the temperature-difference would be smaller, and thus so would the voltage of the thermocouple (right?).

There probably are inductive effects, as well, maybe even accounting for some large percentage of the 2uA... but I'm pretty sure we're seeing something else, here, Thermocouples makes sense.

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I still have ziltch clue as to the other bulb, of the last log. That was weird.

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This bulb is big, slow, and power-hungry... I guess I was pretty lucky all these factors were measurable with a wonky setup and a multimeter.

So, one should now, at least, have a better idea of things to look for when experimenting with new bulbs: 1/15 *resistance* may not be the biggest factor to consider if using milliseconds to read/refresh!