How about R1... how many watts?
Is 2W OK? https://www.aliexpress.com/item/1005006172485377.html

1/4 watt is all that's needed but 2 watts will work OK.

 

Is my connection drawing correct with the 2 lights connected in parallel?
3A fuse should be OK in this situation? Don't wanna burn the car

Also any recommendation for a panel mount socket/plug for the LEDs?
(I opted for barrel=power, jack=sensors)

 

Pinout on the IRF540 is incorrect.
The blue wire should go where the orange wire is.
The orange wire should go where the black wire is.
The black wire should go where the blue wire is.
The barrel connectors should be fine.

 

Hey S,
Would you happen to know how may mW this contraption will be consuming while the reed switch is not triggered?

 

Appx 72 micro watts. The closed switch only draws appx 6 micro amps.

 

I made a to scale diagram in order to find out what box to order.

1. Just soldering the wires as shown should be fine right?
2. Should I just glue the MOSFET with hot glue flat on the box base?
3. I do not suppose the MOSFET will need a heatsink - It should remain completely cool in this application right?
4. Haven't decided on the sensor yet. I need something discreet if I am gonna fix it (double-sided tape) onto the trunk door.







Shopping list: Does not include wiring.
BOX: 61x36x25 is perfect even though it might be too high, so I will try the 60x36x17 clamshell type too.
https://www.aliexpress.com/item/1005006381428975.html
RESISTOR:
https://www.aliexpress.com/item/32914660935.html
RCA plugs & panel mount sockets:
https://www.aliexpress.com/item/33055742680.html
https://www.aliexpress.com/item/32728517134.html
BARREL plugs & panel mount sockets:
https://www.aliexpress.com/item/1005005862425091.html
MOSFET:
https://www.aliexpress.com/item/1005005933352536.html

Subtotal €8.90
Shipping fee €6.07
Total €14.96 (with loads of stuff to spare)

 

1) Wiring is correct.
2) Should be OK.
3) I don't think a heatsink is needed. My calculations show the mosfet only dissipating appx 150mw when the LEDs are ON.
4) I leave that up to you.

 

I suppose I am looking for Normally Open right?
This looks tiny.
Are specs OK? Anything I should look out for?

https://www.aliexpress.com/item/1005006781708562.html

 

Yes normally open
The specs are fine
Don't forget the magnet.

 

I suppose I am looking for Normally Open right?
This looks tiny.
Are specs OK? Anything I should look out for?

That looks like the end sensed type, if so a button or small disc magnet should work.


View attachment 327914https://www.aliexpress.com/item/1005006781708562.html
[/QUOTE]

 

That looks like the end sensed type, if so a button or small disc magnet should work.

One photo on the Link shows a flat magnet next to it.

 

I placed my order and chose this reed switch, which is tiny and is embedded.
I think it is better to drill 2 holes into the trim of the car and bury these in there, rather than glue them on the surface.

https://www.aliexpress.com/item/1005006076142718.html
Rc-33 NO (dark brown color - i guess I can paint them if I want)

 

The one I mentioned in #30 look like the one per #28 is similar to those used on T.M.s for belt motion detection, they use end magnet detection

 

I am actually looking to get one of those too. Thanks again for pointing it out.
I am hoping for the least intrusive solution.

Settled on one of each:
https://www.aliexpress.com/item/4000318373804.html
https://www.aliexpress.com/item/1005006068040994.html

I also found some mini PIR sensors.
e.g. https://www.aliexpress.com/item/1005007296542341.html
https://www.aliexpress.com/item/4000479833042.html

Advantages:
1. I chose these because they can be directed towards the door, mounted on the trunk's side panels. Other kinds will fire towards the other side panel and might not get triggered easily.
2. Using these can directly power the LED's, making our box obsolete.

Their shortcomings are :
1. One has 2A output (borderline amperage for my LED's) & the other 3A (is ok for me).
2. no adjustable delay. You need to be moving every 20s or so. (other types have this and some have light control ie. work only in the dark)
3. anything moving in the trunk while driving will trigger the lights.

Having thought about it, I think I will give it a miss for now.

 

Hello again.
I received all parts today so I put the contraption together.
Unfotunately I think they sent me the wrong reed switch.
I ordered Normally Open, but I got a Normally closed I believe, since I get 12V output when the magnet and sensor are together.
Here are some photos.

 

Hello again.
I received all parts today so I put the contraption together.
Unfotunately I think they sent me the wrong reed switch.
I ordered Normally Open, but I got a Normally closed I believe, since I get 12V output when the magnet and sensor are together.
Here are some photos.

I just tested the reed switch and it is actually a NO as I ordered.
The problem seems to be the actual circuit.
It looks like it passes through the 12V by default and shuts it down when the reed switch closes (ie when the magnet moves away).
I want it the opposite way.
ie. 0V by default... ie. when sensor is open (ie magnet is far).
12V when sensor is closed (ie magnet is near).

Video:

@sghioto could you take a look please?

 

I just tested the reed switch and it is actually a NO as I ordered.

Do you have the LED module connected?

 

Do you have the LED module connected?

No... still testing on the bench as you see in video.
Using multimeter to test.

 

Rewire the Reed and resistor like this:

 

Is this connection diagram correct as per your update?