TLC555 Day/Nite Circuit

Tinhorn

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Here is a circuit I built a year or 2 ago that can be adjusted so the cam activates when it gets Dark or when it's Daylight.  

Notes:

1.  The LDR (Light Dependant Resistor) is from the MS20

2.  The circuit only works when there is a TLC555 timer used
      The Pin 4 referenced in the drawing is any (existing) timer stage
      (But I put mine on the 2 min stage)

3.  It's easy to get lost when wiring the Switch (DPDT)
         it has 6 terminals
         The "Arrows" on the drawing points at the Terminals
         on the same end of the switch.  The left
         part of the DPDT is drawn "Up-Side Down" to
         make the drawing prettier

4.  I put everything in a small box with a 1/8" Stereo Ear Plug/Jack
         for 24 hr operation, I can then just unplug the sensor

5.  Seal the LDR so that no moisture can get on the terminals

http://content.communities.msn.com/JessesT...amp;PhotoID=501


(Edited by Tinhorn at 10:35 pm on Aug. 16, 2001)
 

gizz

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And it works very well. Tinhorn helped me integrate this day/night sensore into my the videocam to operate the light at night only.
 

Brian

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You may not want to use this circuit but if power drain is a problem then this circuit can help.  Most photoresistors draw a lot of current during peak moments of the day.  I have left a web address where I found this circuit and you can probably integrate it into your designs as well.  The best thing about it is that it draws about 4 to 5 uA at its peak and about 2 to 3 uA at its low.  Be sure and use the MAX931cpa chip for less current draw.  You will get a logical one or zero for an output.

http://dbserv.maxim-ic.com/appnotes.cfm?appnote_number=237

This web address details the workings of the sensor circuit.

Brian
 


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