Author Topic: 12volt Photo Cell ?  (Read 8991 times)

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DrDave

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12volt Photo Cell ?
« on: July 12, 2009, 02:37:04 AM »
I am trying to control some 12v lighting with a photo cell or other type device.  The only one I have been able to locate is the Intermatic/Malibu ML814PR Photo Control from Lowes-Depots. It is designed for Malibu garden lights witch are 12AC not DC.  I tried using this device on 12 DC and had no luck.  I think I Harry Pottered the first one (no sparks so it wasn't a full Harry Potter).  So I returned it for a new one.  Before I gave it the good old second try, I thought I would ask advice.

The lights are 12v dc and draw about 1.25amps from my PV battery system.  Anybody got a solution to making them come on at dark using 12volts dc.

Thanks for the help guys.
« Last Edit: July 12, 2009, 02:37:04 AM by (unknown) »

ghurd

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Re: 12volt Photo Cell ?
« Reply #1 on: July 11, 2009, 10:15:53 PM »
LM741 and a CDS cell...

http://www.uoguelph.ca/~antoon/circ/sensor2.htm


I would make a few changes to use a power fet instead of a relay.

G-

« Last Edit: July 11, 2009, 10:15:53 PM by (unknown) »
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Basil

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Re: 12volt Photo Cell ?
« Reply #2 on: July 12, 2009, 05:33:45 AM »
Try a 12 volt relay with NC and NO contacts with a 1.3 watt panel from FH. Just wire it so that when the sun hits the panel that the relay comes on and opens the contacts to cut the lights off. Sun goes down and the relay drops out, Lights come on.
« Last Edit: July 12, 2009, 05:33:45 AM by (unknown) »

Norm

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Re: 12volt Photo Cell ?
« Reply #3 on: July 12, 2009, 10:32:48 AM »
Why can't you just modify a small solar yard light

to electronically turn on another on - off switch

to a larger lighting system?
« Last Edit: July 12, 2009, 10:32:48 AM by (unknown) »

DrDave

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Re: 12volt Photo Cell ?
« Reply #4 on: July 12, 2009, 05:13:01 PM »
ghurd,


Thanks for the link. I built one today. It works great, but as you mentioned, probably should use a Pfet.  The relay is wasting amps.


ghurd, can you recommend a proper fet and how it should be tied in.

How many amp is a fet good for?


Here is a list of the Radio Shack part # if anybody wants to make one.

I spent $12 on parts.

List doesn't include a relay or the optional resistors, I had some.


271-1335 10k Resistor

271-1317 470 ohm

271-1321 1k

271-282 10k trim pot

276-1657 LDRs

276-0007 LM741 opamp

276-1101 diode

276-2017 transistor

« Last Edit: July 12, 2009, 05:13:01 PM by (unknown) »

ghurd

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Re: 12volt Photo Cell ?
« Reply #5 on: July 13, 2009, 05:18:43 AM »
Dave,

I will make a guess at some of the contents of your junk box.  Shoot me an email if I messed up.


IRFZ44N power N-fet would be great for 1.25A.

The Gate goes where the Base is shown in the diagram.

The Source goes where the Emitter is shown in the diagram.

The Drain goes where the Collector is shown in the diagram.


Change R5 to 51K or 100K.


The 12V LED bulb replaces the relay in the circuit.  + to +, bulb - to N-fet Drain.


D1 1N4001 can be left out.


If it does some excessive blinking before fully committing to On or Off, try a 180K or 220K between pin 6 and 2 on the LM741.


Only 2 more days until the next Harry Potter movie is released.

I wonder if that is a sign?

G-

« Last Edit: July 13, 2009, 05:18:43 AM by (unknown) »
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DrDave

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Re: 12volt Photo Cell ?
« Reply #6 on: July 13, 2009, 05:49:15 PM »
Will give it a try.  


Thanks

« Last Edit: July 13, 2009, 05:49:15 PM by (unknown) »

fernbrae

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Re: 12volt Photo Cell ?
« Reply #7 on: July 15, 2009, 12:44:26 AM »
Hi ,

I have the product that you are looking for ,it comes from Hafele Australia

Sensor switch Article number 830.85.392

This will do as you require ,I do the same thing at my home ,control Led lights

automaticaly come on at dusk and turn off at Dawn.

You will need to purchase a 1 Mtr extension lead and cut in half .

The lead has special plugs that are waterproof and 2 pin connectors .

Go to

www.hafele.com.au

then scroll down to the online catalogues and download the Reflections Lighting catalogue ,this switch is with the deck lights.

Rgds

Greg
« Last Edit: July 15, 2009, 12:44:26 AM by (unknown) »

ghurd

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Re: 12volt Photo Cell ?
« Reply #8 on: July 15, 2009, 12:19:00 PM »
Some people could modify an old one,

but the new ones have tiny little parts.

I can barely see the new parts, let alone figure them out!


But it would work.  :)

G-

« Last Edit: July 15, 2009, 12:19:00 PM by (unknown) »
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DrDave

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Re: 12volt Photo Cell ?
« Reply #9 on: July 15, 2009, 04:27:27 PM »
Ghurd,


I made another with the parts you recommended.  Seems to be working fine on the bench.

Put it on the lights about 30 min. ago.  Waiting for it to get dark.


For some reason, it doesn't seem to draw any additional amps at all.  Now that is cool.


thanks to the wizard.

« Last Edit: July 15, 2009, 04:27:27 PM by (unknown) »

answers

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Re: 12volt Photo Cell ?
« Reply #10 on: May 14, 2010, 03:39:38 AM »
I am trying to control some 12v lighting with a photo cell or other type device.  The only one I have been able to locate is the Intermatic/Malibu ML814PR Photo Control from Lowes-Depots. It is designed for Malibu garden lights witch are 12AC not DC.  I tried using this device on 12 DC and had no luck.  I think I Harry Pottered the first one (no sparks so it wasn't a full Harry Potter).  So I returned it for a new one.  Before I gave it the good old second try, I thought I would ask advice.

The lights are 12v dc and draw about 1.25amps from my PV battery system.  Anybody got a solution to making them come on at dark using 12volts dc.

Thanks for the help guys.

The photocell you have that works on AC will use a semi-conductor switch and will never work on DC. I have found one in the uk for my solar chicken door project that works on DC. Got it from www.photocell-switches.co.uk it took about a week for it to arrive but you try finding one.


« Last Edit: January 16, 2011, 09:50:54 AM by wooferhound »

ghurd

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Re: 12volt Photo Cell ?
« Reply #11 on: January 11, 2011, 09:09:20 AM »
The original circuit has moved.
It is now here as Fig 12.
http://www.sentex.ca/~mec1995/gadgets/741/741.html

G-
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dnix71

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Re: 12volt Photo Cell ?
« Reply #12 on: January 11, 2011, 10:13:13 AM »
http://www.backwoodssolar.com/catalog/lights.htm#12%20volt%20DC%20NIGHT%20WATCHMAN%20PHOTOSWITCH  $40 and three wire hookup.

Marine rated, so your outdoor use should be okay. Fairly high amperage rating with low standby draw.
« Last Edit: January 11, 2011, 10:15:02 AM by dnix71 »

DamonHD

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Re: 12volt Photo Cell ?
« Reply #13 on: January 11, 2011, 10:28:12 AM »
This circuit of mine, though I'm using it for mA, might be good enough for A.

http://www.earth.org.uk/LED-lighting.html#homebrew-nightlight

The main issue would be in twilight with the FET partly on.

Rgds

Damon


kitestrings

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Re: 12volt Photo Cell ?
« Reply #14 on: January 14, 2011, 12:03:13 PM »
Hi,

I've used now two of these:

http://www.backwoodssolar.com/catalog/lights.htm#12%20VOLT%20DC%20MOTION%20SENSING%20LIGHT%20SWITCH

I'm not sure where I bought them.  They were ~$75 at the time.  They've been reliable and allow for the typical settings of sensitivity, day/night (photocell or just motion), and delay.

~kitestrings

yuandrew

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Re: 12volt Photo Cell ?
« Reply #15 on: January 25, 2011, 09:47:46 PM »
I may be late in contribution but if you're looking for a unit that is ready-made, I found this at the SoCal Solar Store where I've been working. Forgot we had two of these laying around.


http://www.flexcharge.com/flexcharge_usa/products/night_watchman/night_watchman.htm
« Last Edit: January 25, 2011, 09:54:14 PM by yuandrew »