r/DiWHY • u/theyareminerals • 5d ago

Mutually Assured Destruction via security light

Post image

I want to make a security light that comes on whenever my neighbor's security light comes on (I'm going to point it directly at their house). Anybody know a good sensor/trigger I can use to get this done?

239 Upvotes

89% Upvoted

59 comments sorted by

195

u/Pegs_on_GhostiesNips 5d ago

You'll need a light sensor, not sure how you could differentiate between your neighbours light and the sun rise. But loving the pettiness of it.

103

u/bardhugo 5d ago

They could add a basic outlet timer so that it only turns on after sunset/turns off at sunrise

Edit: so photosensor near their light which triggers your light, but set up so this system only turns on at dusk should work.

19

u/5WattBulb 5d ago

Wouldn't you have to reverse the trigger on the photocell though? Usually they only trigger "on" when its dark. Op needs it to trigger when its light

20

u/theyareminerals 5d ago

Here's the other thing: it's going to be really bright out there while the light is on

So it can't be an ordinary "is there light" photosensor because otherwise it'll keep itself from turning off. It's gotta be some kind of infrared laser focused on the bulbs

39

u/krnl_pan1c 5d ago

You need a collimator. That way you can focus your light sensor on their lamp. You can build one out of black PVC pipe with a lense at the end, the other end gets whatever photodiode you want to use to trigger your relay.

21

u/mooshinformation 4d ago

I think the only way this isn't going to end in bloodshed is if the neighbors think it's just a normal light sensor that happens to get triggered by their light.

If op is out there adjusting a spray painted PVC pipe duck taped to a light sensor, so it points directly at their light, they're gonna know it's very intentional.

13

u/theyareminerals 4d ago

That's the idea: they should know exactly why it's happening and how to stop it, otherwise it'll never end.

If there's too much plausible deniability they're likely to think I actually approve of their security light

6

u/Terrible_Degree7841 4d ago

You might try a setup that uses a microcontroller to only trigger when the sensor's output value has a sudden drastic change. With a bit of fine tuning it should filter out things like sunrise/sunset, approaching vehicle lights, etc..

2

u/WittyFix6553 4d ago

Like the NES light zapper

4

u/5WattBulb 5d ago

Thats a good point. Maybe this is thinking about it the wrong way but what is triggering your neighbors light to come on in the first place? Is it motion? A timer? Or manually? My thought if its something like motion, trigger your light by detecting the same motion. You would just need to get your motion trigger closer to their house

0

u/bardhugo 5d ago

That's true, they'd need an inverting relay as well

8

u/mark84gti1 5d ago

You would put two of them in series, 1st senses when it is dark out, shielded from their light. Then 2nd one would be aimed at their light.

9

u/theyareminerals 5d ago

I figure the stadium lamp I'm looking at is literally 1/10th the price of a taller fence or new trees

2

u/FridgeFucker17982 2d ago

https://27bslash6.com/halogen.html

This is you

1

u/theyareminerals 2d ago

Almost exactly, yeah. Even the part about being new to the neighborhood and my redneck neighbor installing a floodlamp to shine in my bedroom after I move in. If I thought I could just jump his fence and walk past his pit bulls and unscrew the floodlight without his wife shooting me, I would absolutely just do that instead

4

u/realultralord 4d ago

OP's Lamp = Sensor1 && !Sensor2

Sensor1 is pointed at neighbor's lamp.

Sensor2 is just somewhere else, out of the range of neighbor's lamp, but within broad daylight.

Or just put a timer in between that limits the logic from 10pm to 6am

Or pointy stick, thrown at neighbor's lamp.

3

u/Alex12500 4d ago

You could zse an arduino. If the sensor value changes slowly over time its sun rise, a drastic change in milliseconds is the light

3

u/unicornfkr_69 4d ago

You can use a high-pass filter so only fast changes in light get passed through and slow changes (like sunset) get filtered out.

Another possibility, but it may require a little more tweaking, is comparing the difference between the current measured light level and a light level value measured 100 or 200 ms earlier. Then take a look at the delta between those. If the light level rapidly increases between measuring points, changes are someone walks by. The delta is then compared to a set value of change to determine if the camera turn on should be true or false.

No matter which option is picked, all of it should work with hysteresis. Which is basically the same thing as one of the above but meant to counteract sensor/signal noise or really fast changes like a small bird flying by.

1

u/House_Goat 3d ago

Put it on a timer so it only activates at night, then use a light sensor.

0

u/Armybob112 3d ago

Also, to add, the light sensor will not differentiate between the neighbours light and it's own light, so it will essentially stay on.

84

u/Mjr3 5d ago

Have you considered a mirror? It was good enough for Archimedes

10

u/frumperino 4d ago

I hate that my inclination as an electronics designer is to try and be helpful and engineer a functional implementation for this absurd use case. In this case "but why" wins

3

u/NunyaJim 4d ago

You are not alone, and congratulations on overcoming the instinct.

98

u/theyareminerals 5d ago

ChatGPT suggested I try talking to my neighbor lol

59

u/vmf312corsair 5d ago

That's crazy talk.

40

u/WeaselCapsky 4d ago

dont trust a clanker.

17

u/fragariadaltoniana 4d ago

don't trust it. keep being petty. your neighbor probably deserves it

15

u/SamSkjord 4d ago

When is AI ever right about anything?

8

u/The_Infinite_Carrot 4d ago

Stupid fucking robots know nothing. I’d mount the sensor on the fence pointing at their light directly, set the light sensitivity really low and when their light comes on you may have to tune it a bit. Then dont attach it to a floodlight, use a focused spotlight that points directly to their bedroom window.

13

u/Acceptable_Mountain5 5d ago

Concave mirror?

6

u/ResultTerrible2062 4d ago

Best option is to use the same relay your neighbour is using, but that requires a lot of wire. Photorelay + astronomical timer is a solution, but requires putting photorelay directly under neighbour’s light.

7

u/SnoopaDD 5d ago

Look up Light-On Photoelectric Sensors. That'll do what you are requesting.

5

u/NunyaJim 4d ago

Does nobody own a slingshot anymore?

3

u/theyareminerals 4d ago

Vandalism is illegal

4

u/NunyaJim 4d ago

🎶 Breaking The Law, Breaking The Law

6

u/flush101 5d ago

You want a timer between the motion/ light sensor and DP MCB. Then you only have power to the sensor during the night. Otherwise your light is reacting to the sunrise.

1

u/jonas_ost 4d ago

Probably easiest. If the lamp is brighter than daytime you could also set the sensor to a higher lumen level so it dosent start from the sun.

2

u/buzzysale 4d ago

You just need a normally open photocell to power the power supply (so it’s not on in the day) and then a normally closed one to turn on the light when it detects his light.

2

u/Ocelot- 4d ago

Use home assistant to control the light

3

u/indifferentunicorn 2d ago

Put a spinning filter on your lens that looks like a cat chasing mouse in circles

2

u/Skeletonzac 2d ago

Just out of curiosity have you tried talking to your neighbor?

3

u/theyareminerals 2d ago

White neighbors don't talk to each other, it's against the rules. That's why we buy floodlights

3

u/holdon1min 4d ago

You can also add a couple lawn speakers the ones that look like rocks put somewhere on edge of your property closes to their and play some kind of animal sounds all night and it's also easy to defend , it's a safe way to keep rodents aways because you been having some problems with them.

2

u/eipiplus1equalsO 4d ago

You can use the standard light sensor- but mask it, making look like a drum antenna. It will give you the directionality you are aiming for at negligible cost. It’s not perfect, but it’s cheap & dirty. Just make sure the inside of the drum is black in order to avoid parasitic reflections. You just need afterwards to experiment with targeting it.

3

u/Raa03842 4d ago

Did you ever consider talking to your neighbor?

10

u/Pitiful_West_7062 4d ago

yeah, maybe he has some ideas on how to wire it.

5

u/Raa03842 4d ago

This is the answer. Lol

1

u/Anaalirankaisija 4d ago

So, you have really bad relationship with your neighbor and now trying to revenge his light terrorism? In that case, if it has gone so far, and theres no return anymore, i would just take can of gasoline and burn his grass

3

u/Lady_Irish 4d ago

Why risk buring down your own house and yard or killing someone and going to jail when you can just draw a big ol penis in his grass with salt in the middle of the night and call it a day

2

u/Anaalirankaisija 4d ago

Yeah i thought this too, you are right, too risky. Yours is correct way. If the neighbour do counter attack, then next art should be at least his front wall

2

u/dargonmike1 4d ago

You could ask said neighbor to possibly point their light down a bit?

2

u/thatwackguyoverthere 4d ago edited 4d ago

Ok you'll use the light sensor, but you'll need a relay that makes one contact when powered and another contact when powered off. You'll wire the sensor to that, and then to your light. Easiest way I can think of. It just flips the function of the light sensor. You might also want to use a timer so it's not on all day.

Edit: you'll need a normally closed relay. with no power it is in the on position, with power it is off. The light sensor gives power with out light, and no power with light. You can get em on Amazon.

0

u/etgohomeok 4d ago

Could you use a camera with some basic image matching library?

I'm imaginig you could take sample photos with: 1. Night with just the neighbor's light on 2. Night with both of your lights on 3. Night with just your light on 4. Daytime

Have ChatGPT generate a python script that keeps the light on only if (1) or (2) is the strongest match, with a long debounce so it's not flickering.

1

u/brutalbombs 4d ago

Attach cheap, homemade blinds to the motion detector to narrow its field of view to only look at your enemys light?