Can you walk me thru a photocell switch...

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  #1  
Old 04-10-17, 01:22 PM
J
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Can you walk me thru a photocell switch...

I need to 'reverse' the function from 'On at Dusk' to 'On at Dawn'. I have an electric auto radiator fan to install on a 40' shipping container and need to suck out the humid air inside (I get dripping off the ceiling) during the day when humidity is lower.

The Photocells are dirt cheap ..it's just I am clearly not smart enough to wire this switch. Hell, I have difficulty with 2 wires becoming three then two again, the regular way?!

As a visual person (lucky I have a spell checkler..) please scratch it onto a piece of paper and post an image, so I can study it. Thanks for the help. Jim


Additional background information
http://www.doityourself.com/forum/el...ar-panels.html
 

Last edited by PJmax; 04-10-17 at 08:14 PM. Reason: added link to previous thread
  #2  
Old 04-10-17, 01:31 PM
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This is obviously a continuation of your already started container thread.

Logically you should solar panels to directly power the fan.
When there is daylight...... there is power..... the fans runs.

Photocells are dirt cheap and run on 120vac power..... not 12vdc.
 
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Old 04-10-17, 06:48 PM
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PJ knows more of what you are doing but I will throw my 2 cents in:

You need a contactor or relay with Normally open/ Normally closed contacts. You want the normally closed contacts. The photo cell will trigger at night and open the contacts and shut off the fan. Then when it gets light, the photocell will open and close the contacts.

This will not work with DC.
 
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Old 04-10-17, 07:37 PM
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They also make inexpensive 24 hr timers. Also, sounds like you are more concerned about humidity. One of the problems with a fan is running it when it is raining outside and bringing in 100% humidity day or night. Gets a bit more complex but you could monitor RH inside and outside to determine when to run the fan.

Bud
 
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Old 04-10-17, 08:05 PM
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They do have humidity sensors designed for bathroom fans. Maybe something like that would work for you?
 
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Old 04-10-17, 08:17 PM
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I added a DIY link to the OP's opening post. This container is apparently far from 120v power and will require batteries and solar cells.

We actually need to see how that was accomplished and work with it.

Normally in an application like this.... a DC fan directly powered from solar cells is very effective. A radiator fan would not be the best choice as they draw 15+ amps at 12vdc.
 
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Old 04-11-17, 06:55 AM
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Photo cells do not work. As PJM stated, the radiator fan draws too much current. I hooked three panels (I have) together. This fan is also one 'I have'. As well as a 120/12v power supply - 'I have.' I would rather cobb together what I have rather than start new.

I could have bought a series of powered boat vents, but these are things I have. It's oly a 30' walk to flip a switch manually, that may be the easiest solution. Paraphrasing Bud9051; "It's raining - now what?!" Thanks. I'll figger it out. Cheers.

Jim
 
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Old 04-11-17, 03:03 PM
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I hope you guys are not trying to say that low-voltage DC photocells do not exist, they surely do. Just do a Google for dc photocell.
 
 

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