I have an application where I need to reliably detect night time, i.e. darkness, not just bad weather or a shadow but nighttime, a current product has an issue of activating in moonlight or with car headlights, any ideas ?
Detecting night time
I have an application where I need to reliably detect night time, i.e. darkness, not just bad weather or a shadow but nighttime, a current product has an issue of activating in moonlight or with car headlights, any ideas ?
|
Maybe...
The moon/bad weather could be solved by adjusting the sensitivity. I will assume you are using an ADC for this. Have the sensor shaded from the moon directly. Adjust so moon light appears as clouds or bad weather.
The car lights ... Maybe a counter. The light would have to hit the sensor for a predetermined time (count) before it is activated.
Dave
Always wear safety glasses while programming.
|
Nice application. I would think you can use photo sensors placed in directional tubes facing opposite directions like left and right separated by a tall barrier. This will ensure only night / darkness on both sensors will trigger your circuit. I'm too lazy to sketch it out right now
|
>a current product has an issue of activating in moonlight or with car headlights, any ideas ?
Sensitivity adjustment will take care of moonlight.
An activation/deactivation Time-Delay will take care of Car Headlamps.
A Time-Clock will take care of switching during Daylight Hours. Most places on the planet publish "Lighting-Up" Times.
A combination of all three should give you a better product.
Oh... and sensible positioning of the Sensor (like pointing skywards - and not towards where the moon normally traverses) always helps!
|
Or you could eliminate all this automatic stuff by handing it to someons sitting at a window with the following short instructions:
If dark = 1 then turniton 'now night
if dark = 0 then turnitoff 'now day
This would also help with the unemployment problem, but probably not with sales.
------------------------------------------------------------------
Oh dear, I am sorry, I just couldn't resist.
Yeah, I know, some people are just no bloody help at all, are they?
I'm just gonna go sit in the corner for a while
Peter Moritz.
Up the bush, Western Plains,
New South Wales,
Australia.
|
Muddy little help but made me smile
Still thinking about this, I have had another idea and quite a good one I think, how about using a small solor panel.
|
Since there is effectively no naturally-occurring infrared (IR) in the night sky but lots of it during the day (even when overcast), would an IR photodetector be a possible solution?
Russ
N0EVC, xWB6ONT, xWN6ONT
"Easy to use" is easy to say.
|
with my hobby projects I use a 10k pot,1k safety resistor and 10k photo cell
you can add a little "debounce delay " for the headlights and cal with the pot
Code:LDR=1 'POWER UP LIGHT SENSOR Pause 20 ADCIN 0,NIGHT 'READ AN1 & STORE IN NIGHT VAR PAUSE 250 IF NIGHT=<400 then IT'S DAY SO DO THIS IT'S NIGHT SO DO THIS Pause 25 LDR=0 'MAKE SURE LDR/ADCIN POWER IS OFF
" be nice it's people like me that make people like you look smart"
yes I read the datasheet, of the 300 pages I understood 10
|
Here is an example of a delay to avoid headlight induced lights off.
Code:LIGHTS VAR PORTA.0 DAY VAR PORTA.1 MAIN: IF DAY = 1 THEN PAUSE 10 IF DAY = 1 THEN LIGHTS = 0 ELSE ENDIF ENDIF LIGHTS = 1 GOTO MAIN END
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
.
Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
.
There simply is no "Happy Spam" If you do it you will disappear from this forum.
Members who have read this thread : 0You do not have permission to view the list of names.
Posting Permissions
Bookmarks