CFL on photo on/off?
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From: Samuel M. Goldwasser on 11 Mar 2010 19:00 Meat Plow writes: > What is the problem with operating a CFL on a dusk to dawn device that > uses a photo sensor? Does it suffer the same fate as running the CFL > on a dimmer that is full on? That's my guess. My motion sensor > security light has an option to turn the lamps on manually and shut > them off in the morning automatically when it's light enough out. But > it has a relay that makes an aduible click. I would assume a simple > light sensing fixture is switched with a triac and this causes a > pulsedvoltage that harms the CFL ballast. The problem is that these photosensitive devices draw their power through the lamp, so there's a trickle of current flowing even when it's supposed to be off. With an incandecent lamp, this doesn't matter. But with a CFL, if you're lucky, the result is the lamp flashing on momentarily like a strobe periodically but no damage to it. :) -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.
From: Allodoxaphobia on 11 Mar 2010 21:27 On 11 Mar 2010 19:00:12 -0500, Samuel M. Goldwasser wrote: > Meat Plow writes: > >> What is the problem with operating a CFL on a dusk to dawn device that >> uses a photo sensor? Does it suffer the same fate as running the CFL >> on a dimmer that is full on? That's my guess. My motion sensor >> security light has an option to turn the lamps on manually and shut >> them off in the morning automatically when it's light enough out. But >> it has a relay that makes an aduible click. I would assume a simple >> light sensing fixture is switched with a triac and this causes a >> pulsedvoltage that harms the CFL ballast. > > The problem is that these photosensitive devices draw their power through > the lamp, so there's a trickle of current flowing even when it's supposed > to be off. With an incandecent lamp, this doesn't matter. But with a CFL, > if you're lucky, the result is the lamp flashing on momentarily like a strobe > periodically but no damage to it. :) I hedge my bets: In a 2 lamp device I use 1 incandecent and 1 CFL. :-) Jonesy -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 * Killfiling google & XXXXbanter.com: jonz.net/ng.htm
From: Samuel M. Goldwasser on 12 Mar 2010 08:24 Allodoxaphobia <bit-bucket(a)config.com> writes: > On 11 Mar 2010 19:00:12 -0500, Samuel M. Goldwasser wrote: > > Meat Plow writes: > > > >> What is the problem with operating a CFL on a dusk to dawn device that > >> uses a photo sensor? Does it suffer the same fate as running the CFL > >> on a dimmer that is full on? That's my guess. My motion sensor > >> security light has an option to turn the lamps on manually and shut > >> them off in the morning automatically when it's light enough out. But > >> it has a relay that makes an aduible click. I would assume a simple > >> light sensing fixture is switched with a triac and this causes a > >> pulsedvoltage that harms the CFL ballast. > > > > The problem is that these photosensitive devices draw their power through > > the lamp, so there's a trickle of current flowing even when it's supposed > > to be off. With an incandecent lamp, this doesn't matter. But with a CFL, > > if you're lucky, the result is the lamp flashing on momentarily like a strobe > > periodically but no damage to it. :) > > I hedge my bets: In a 2 lamp device I use 1 incandecent and 1 CFL. :-) Good solution! The only concern would be if the photosensor device doesn't switch (mostly) on or off cleanly. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.
From: William R. Walsh on 12 Mar 2010 10:02 Hi! > The problem is that these photosensitive devices draw their power > through the lamp, so there's a trickle of current flowing even when > it's supposed to be off. With an incandecent lamp, this doesn't > matter. I'm glad someone brought this up, because there is something I'd like to know. I've got an outdoor porch light on a post that has a 100 watt equivalent CFL bulb in it. The fixture itself is made of cheap plastic, and the light is on fairly often, so I feel better using the CFL as opposed to a 100 watt incandescent. (However, I haven't noticed a maximum wattage rating on the fixture itself.) I'd like to switch this light via photocell. To prevent any possible "abuse" to the CFL, I'd like to have the photocell device turn a relay on and off. Is it possible to do that, or would it result in unacceptable behavor (buzzing, etc) from the relay? If it won't work, I could always use a timer of some sort. William
From: David Nebenzahl on 12 Mar 2010 13:42
On 3/12/2010 7:02 AM William R. Walsh spake thus: >> The problem is that these photosensitive devices draw their power >> through the lamp, so there's a trickle of current flowing even when >> it's supposed to be off. With an incandecent lamp, this doesn't >> matter. > > I'm glad someone brought this up, because there is something I'd like > to know. > > I've got an outdoor porch light on a post that has a 100 watt > equivalent CFL bulb in it. The fixture itself is made of cheap > plastic, and the light is on fairly often, so I feel better using the > CFL as opposed to a 100 watt incandescent. (However, I haven't noticed > a maximum wattage rating on the fixture itself.) > > I'd like to switch this light via photocell. Keep in mind that CFLs are often not good candidates for this kind of application, because the length of time they take to warm up is often the same as the length of time they're on, so they don't do a very good job of lighting up the area you want illuminated. For an intermittent application like this, it's probably just as cost-effective overall just to use a good old-fashioned incandescent lamp. -- You were wrong, and I'm man enough to admit it. - a Usenet "apology" |