An engineer's idea for motion sensing light

ctfjr

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Rube Goldberg has nothing on me :)

When I wired our house 30+ years ago I neglected to properly allow for lighting the back yard. There is a wall washer and spot but because of the angles of the house and the extension out of the deck most of the back has very poor lighting.

I have been using up to 48v dc lines to feed my camera system in the woods with 12v reducing devices at the cameras / lights. It allows for using smaller wires because of the lower current draw on the 48v side. I drew up a plan to used 12-24 volt 50w led floods mounted on the face board of our deck, 10 feet off the ground, which is about 100 linear feet.

The plan is to have several 12v motion sensing devices placed along the length of the deck along with a number (to be determined - right now it looks like 5) of the 50w led floods.

When any one of the motion sensors is actuated it sends a 12 volt signal to the trigger line on an adjustable delay on break card. The card pulls in a 12 volt 20amp rated relay that sends ~20v out to the floodlights.

In addition I have a wifi card installed in the box that when activated will also trigger the delay card. I can then control the lights from my phone or computer.

The total delay is the on time of the triggering device (motion sensor or wifi card) + the delay I set on the card (.1 sec to 9999 minutes). When the basic system is in there will be several switches install on the deck so the lights can be switched on even though there is no motion in the yard.

It's a fun project. With the weather being crappy the last couple of days I have the box 99% done, just waiting for an ammeter to put on cover. I hope to start the deck wiring / mounting of the lights today.

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The temp power supply in the rear is actually supplying 18.98v not 98. Must have been camera flicker.
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Henro

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I almost hesitate to say this as I did not have the energy to read your post in detail, and understand what your are attempting to accomplish.

BUT I think after a couple decades of working as an engineer in an industrial environment, that it might have been easier just to run 120 VAC out over the existing wires (which I assume are rated to handle that voltage) and just use devices locally that would covert the voltage to what was needed.
 

BruceP

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it might have been easier just to run 120 VAC out over the existing wires (which I assume are rated to handle that voltage) and just use devices locally that would covert the voltage to what was needed.
I am suspecting the 48v DC is pulled from solar-charged, battery bank.... but I am sure the OP will clarify.
 

ctfjr

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Sorry if I didn't explain myself well here :(

There is no existing wiring on or under the deck itself for lighting.

No, no solar system - though I dearly want one. In this case I'm using a 0-24v variable switching supply. I found the lights use about 40+ watts when the supply voltage is ~18v to them. Running 14ga wire means no concern over voltage drop even with 5 or 6 lights.

For my camera system in the woods the total wire run is 1000' or more. Using a 48v supply the few volts drop in the wire means nothing. The 12v converters will work with an input voltage above 15v.

So why not a conventional 115 volt system? I have wired two houses completely so I could do that. This system allows me to set the delay to anything I want - probably 30 minutes or more. When we let the dogs out they wander into the fenced in area of the woods, far from the house. These lights will illuminate them and stay on even though they are far from the sensors.

I will have remote control via the internet or my lan for the lights, not so with a conventional 115v system.

I'm pretty sure multiple sensors are possible with a 115v system.

Other than an 'on/off' switch wired to the top of the deck with a 115v system I will be able to place low voltage, momentary switches in 2 or 3 spots on the deck to trigger the lights on. Barring any motion in the yard they will turn off after the set delay.
 

xrocketengineer

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That looks impressing. The Space Shuttle was simpler, and I know about that. :eek:
 
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ctfjr

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In the 60's I worked at the MIT Instrumentation Lab. The materials today are a lot more compact / complex :)
 

The_Wingnut

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Impressive...who says an engineer can't actully build what they design?
 

fried1765

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That looks impressing. The Space Shuttle was simpler, and I know about that. :eek:
Outdoor electrical connection corrosion will be just lurking...... for the opportune time to attack this overly complicated little gimmick!
 

ctfjr

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Outdoor electrical connection corrosion will be just lurking...... for the opportune time to attack this overly complicated little gimmick!
Ye of little faith :)

All the electronics will be inside, nice and cozy.
Only 4 wires will be going to each light / sensor location:
Common negative (12 and 24 volts) - 14ga
24v positive for powering the lights - 14ga
12v positive to power the sensor -18 ga
sensor triggered wire - 18 ga

There will be a lot of soldered joints out there.
 

fried1765

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Ye of little faith :)

All the electronics will be inside, nice and cozy.
Only 4 wires will be going to each light / sensor location:
Common negative (12 and 24 volts) - 14ga
24v positive for powering the lights - 14ga
12v positive to power the sensor -18 ga
sensor triggered wire - 18 ga

There will be a lot of soldered joints out there.
Probably depends a lot on where you live.
My house is only 600' from a salt water inlet, and less than a mile from the open ocean.
EVERYTHING corrodes......RAPIDLY.......even when initially sealed!!
 

ctfjr

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Probably depends a lot on where you live.
My house is only 600' from a salt water inlet, and less than a mile from the open ocean.
EVERYTHING corrodes......RAPIDLY.......even when initially sealed!!
I should have been more clear. All the electronics will be nice and cozy inside the house.
 

JimmyJazz

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All your effort will have been worth it when you collect the reward for proving via your elaborate Trail-Cam-Gizmo(TCG) that Bigfoot does indeed exist. You can then sell the TCG (patent pending) to your ardent followers. We will all say we saw it here first and thought you were a bit off...........America!
 
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ctfjr

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All your effort will have been worth it when you collect the reward for proving via your elaborate Trail-Cam-Gizmo(TCG) that Bigfoot does indeed exist. You can then sell the TCG (patent pending) to your ardent followers. We will all say we saw it here first and thought you were a bit off...........America!
Top of the driveway cam a few months ago Video
 
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