19 Dec
2015
19 Dec
'15
8:08 a.m.
Bulbs have a
lower than normal resistance when cold [...]
Three or four 15 ohm resistors in parallel would probably make a
better load for the -12V line.
Unfortunately I don't have enough of these to
hand, and the local
shop (Maplin) does not have enough in stock. But getting something in series to measure load is
going to be really
awkward, [...]
As in, you don't have any such thing to put in series, or you don't see
a good way to get it in series? I've got a couple of 0R1 resistors
which work nicely for that in conjunction with a voltmeter that can
handle millivolt measurements; you might be able to get something
similar. Mine are 10W, and, while they are designed for bolting to a
heatsink, they can probably handle at least 2 or 3 watts, which means
some 5-6 amps, in free air. (Though that then drops about half a volt,
which can be a problem when you can't put it on the input side of the
regulation.)
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