Re: GE Energy Saving Light Bulbs

You can use most compact flourescents on a MECHANICAL timer as far as I know, but not with most (all?) electronic timers. When I tried to use one with a low light sensor indoors (on recommendation of a local shop!) the light flashed at about one second intervals when the light should have been off (and the shop took it back when I complained). My particular sensor can tell whether the circuit is complete or not which must mean a low current at least for some of the time. I should be delighted to learn of an electronic sensor that wil detect approaching dusk and switch a compact flourescent on for a predetermined time (preferably not dusk to dawn)

You could get one of these instead...

Andy

'...I should be delighted to learn of an electronic sensor that wil detect approaching dusk and switch a compact flourescent on for a predetermined time (preferably not dusk to dawn)...'

Is this the sort of thing you are after

If the timer or whatever has a neutral connection of it own e.g. those plug in electronic timers, it will be ok. If the timer relies on a small current through a conventional bulb e.g the light switch replacement type, it probably won't work.

For ease of installation, the timers / PIR switches built into light switches keep the same two-wire (no neutral) connection as a basic switch. They power themselves by leaking a little current through the bulb at all times.

If you run a CF from one of these, then the leakage current charges up a capacitor inside the bulb. When this is full enough to almost light the bulb, the bulb may flash briefly as it discharges.

A plug-in timer is OK, as they run from live and neutral. So use one in a table lamp, if you want a burglar-deterrent.

i have one of those...works very well...must have been in use for 2 years now. only prob is in very cold weather it dont light up as bright..but not a prob to me.....still plenty light enuff over my front door. i have mine in a glass white globe screwed to the cieling of my canopy.

rpm

I've had a pair of these working really well for 4 years now.

It would depend on the design of the timer or sensor. The way round using any sensor with one of these is to add a relay.

It is not sufficient that the timer 'plugs in' to a three pin socket. (see my earlier posting in this thread) - perhaps some timers, which may include mine, use only two of the three pins. PS thanks for the replies to my posting.

The electronic timers contain a "Triac" as the switching element; these cut the mains waveform to switch off/on. Because the Energy Saving bulbs have transformers in them, they present an inductive load, thus preventing the triac from switching off correctly. This is the same for fluorescent tubes as they contain a coil (ballast)...

I'm not sure if adding a relay will solve it, because the relay may behave in the same way...

The only solution is to get a detector/timer that includes a relay - if you can arrange to test it in the shop, listen for a 'click' sound as it switches. (put your ear close to but not against the timer!) These should be marked as being compatible with energy saving/fluorescent fittings.

You mean it will be an inductive load, or switch on and off at double mains frequency?

In practice, neither is a problem.

What tends to happen is that the triac turns on briefly when triggered 'on', but then turns off again within tens or hundreds of microseconds because not enough current is flowing, i.e. less than the triac's holding current - it takes time for current to build up (or decay) in an inductance.

Depending on the triac and the resistance/inductance of the load, it is sometimes possible to correct this problem with a 'snubber', a small resistor in series with a capacitor, which you connect across the load.

To experiment, start with those old standby values of 100 ohms (1/2 watt should be plenty) and 0.1 microfarads (rated for 240V. A.C., not D.C.). Increase the capacitance and decrease the resistance until it works. Of course it's much better to have a scope and look at what is happening.

And there are no guarantees!

On a related note I am looking for something that will turn on at dusk but can be set to turn off at a fixed time. Something that in the summer will turn on at (say) 10:30 when it gets dark and turn off at (say) midnight and in the winter will turn on at 5:00 when it gets dark but will still turn off at midnight. With a timer if it is set for winter times (seven hours) then in the summer it won't turn off until 4:30 in the morning.

Just a thought.

Andrew

Try searching on public lighting. I never had a lot to do with it when I was working, but I seem to recollect that half-night PE cells were used.

If you want to use "all-standard" components, plug a light-sensitive lamp or switch (an "on at dusk, off at dawn" jobbie) into a timer which comes on earlier than any possible dusk - say, 3pm - and goes off at the time you want - say, midnight. By the magic of switches-in-series, the lamp will light only when (a) it is Dark Enough, and (b) it's in the timer's 'on window'. Obviously you have to put the timeswitch first in the chain, so it gets supply 24h a day.

For fancier switching I've used a "logic controller" like the Siemens Logo! to handle multiple circuits, PIRs, external on-but-not-off switches, overrides accessible only from inside the house, and so on. But then I'm a geek...

HTH, Stefek