Dan,
So, if I were to try to replace the existing unit (assuming a CFL is desired), should I be looking at motion sensor lights that accommodate flood lights?
Knowing that incandescent light bulbs are being eliminated, I wonder what other folks are doing for their motion sensor type lights?
Frank P.
--- In Electronics_101@yahoogroups.com, "DanielW" <daniel@...> wrote:
>
> It has nothing to do with triacs being "cheap" or units using triacs being cheap; triacs all work the same way: they switch on the AC current at a zero-crossing, but due to the diode drop they actually switch it on just after the zero-crossing. Then they switch off at the next zero crossing, and switch on again ~1V after the next zero crossing. This kind of waveform doesn't work well with the high-voltage switching power supplies that CFL lamps typically use. In short, using triacs to switch CFLs is a bad idea, and if you look at the packaging for any triac-based light-controlling product, it'll say "not recommended for fluorescent lamps", "only recommended for incandescent lamps", etc. Since incandescents are on the way out (and waste so much power anyway), I think it's a good idea to avoid any of these devices for any purpose, not just motion detectors. The new LED lamps shouldn't have this problem (many of them are advertised as being dimmable, which is something almost always done with a triac by turning it on later in the half-cycle), but those are very expensive right now and it might be a while til they're cost-competitive with CFLs.
>
> There's two ways to properly switch CFL lamps. One is with a standard relay; some motion sensor lights have these, and you can hear them click when they turn on. These aren't that unusual because a lot of motion sensor lights are meant to be used with floodlamps, which are higher-current than your typical light bulb, so it may be cheaper to use a relay than a triac large enough for that load. The other way is to use two MOSFETs in a common-drain arrangement.
>
> Dan
>
>
> --- In Electronics_101@yahoogroups.com, "Andrew Mathison \(Alice\)" <mathison@> wrote:
> > A. Some of the Triacs used in such units (usually cheap ones) are simply not
> > man enough for the job of starting any CFL as the CFL take a heavy charge of
> > current at switch on time, that can overload and destroy the Triac within a
> > week or two...if not instantly.
>
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