Simple on at night off at dawn switch


I hope I'm not to far off posting this question on this forum. Some years ago (10) we purchased 4 or 5 simple photovoltaic light switches ( I think they were made by First Alert). We're down to two functioning now, and I cannot find these or anything near to them anywhere (that I've looked!). They were simple plug in the wall then plug your fixutre in and it cycled with day. My wife and I swear First Alert took these off the market because they worked all to well. Now all we see is digital timers etc etc. Anybody have any leads and these simple devices?
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On Mar 23, 7:17 pm, snipped-for-privacy@gmail.com wrote:

I have not seen anything like that. I have see outside style porch lights that have this feature though. Maybe they figured there's more profit to be made in selling you an entire fixture.
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snipped-for-privacy@gmail.com wrote:

with. They make what you describe.
http://intermatic.com/Default.asp?action=prod&pid 2&did=3&cidX&sid7
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Does this have any desirable hysteresis? Their K4123C control cycles 1200 watts of HIDs with a 2-minute period with about 6 footcandles of daylight, esp if some of the light controlled reflects back into the sensor. I'm thinking of adding a 1K resistor in series with the white wire and 39K from there to the red wire to stop the cycling, which wears out the HIDs.
Nick
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Making a minimum 20-minute on-time seems to require more stuff.
I'd like to try 2 resistors first, like this, viewed in a fixed font:
normally-closed thermal relay ------------------- | / relay o | / heater | |---www--- | | Rd | | Intermatic K4123C | | | | | | | photo --- | The photoconductor has a high dark | cond. | ~ | | resistance, about 4K ohms at 6 FC. | --- | . . . .|. . . . .|. . . . |. . . . . V Blk | | |Wht |Red --------- Io| | | Ic| | | v | Rf | ----- |---www-------| HID |--- Vs| ----- | | new | | resistors | | w | Is| w Rs | | w | v | | | | neutral | | -------------------------------------------
20 RDB000!'daylight threshold resistance (ohms) 30 RS300'series resistance (ohms) 40 RF30000!'feedback resistance (ohms) 50 V'7'voltage (volts) 60 IO=V/(RD+RF*RS/(RF+RS))'open-relay current (A) 70 ICS=V/(RS+RF*RD/(RF+RD))'closed-relay series current (A) 80 VCS=ICS*RS'closed-relay series voltage (V) 90 IC=(V-VCS)/RD'closed-relay current (A) 100 HYST0*(1-(IC/IO)^2)'hysteresis (%) 120 SPOWER=ICS^2*RS'closed-relay series resistor power (W) 130 IRF=(V-VCS)/RF'closed-relay feedback resistor current (A) 140 FPOWER=IRF^2*RF'closed-relay feedback resistor power (W) 150 PRINT RS,RF,HYST,SPOWER,FPOWER
Rs ohms Rf ohms Hyst % Rs watts Rf watts
3300 330000 1.970381 .1539285 .1962148
Nick
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snipped-for-privacy@gmail.com wrote:

http://x10.com/promotions/sd533_ed_lightson.html
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http://www.homeclick.com/showpage.asp?itemid 5581

If you don't have your heart set on a photocell, you can also find an astronomic digital timer to do the job. You set the time and what part of the country you are in (there are different zones according to the amount of sunlight during the day). Then forget about it.
I have one and every few years I have to change the battery and reset the clock, in case it drifts. Other then that, no maintenance or attention is required. See the link below.
http://www.homeclick.com/showpage.asp?itemid 5581
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