I have installed some LED lights that come on when you open a locker.
This is the locker over the cooker with the lights on.
And off, for comparison, and this was a bright sunny day!
I bought a roll of self-adhesive LED strip from Bedazzled. Who provide the best LED replacement lamps. The whole boat is equipped with Bedazzled lamps.
https://bedazzledledlighting.co.uk/product/flexible-strip-14-4wm-300-led-5m-colours/
These are Ultra-bright LEDS at 1170 Lumens/metre, most LED strips are nowhere near that bright.
It is £75 a reel of 5metres. That’s for 100 3-led 50mm sections. Or 75p each.
Inside the locker are three strips of 3 LEDs arranged to give maximum illumination.
The strip is marked every 50mm, which is three LEDs, for cutting. So 1 metre is 20 3-led sections
Each 3-led section needs 40mA at 12v to drive it.
I chose to put three of the 3-led sections in each locker. So that’s 120mA per locker. At 12 volts that’s 1.5 watts
The problem with LED strip is that it needs a driver to provide a clean 12volt supply.
Most of the driver units commercially available are mains driven, and I wanted to run these off the normal boat 12v supply.
Luckily RS components have some nice 12 volt supplies. I picked a range of miniature units from Cosel that come in 1.5, 3, 6 and 10 Watt power ratings. They all work between 9 and 18 volts input, ideal for a boat.
Even so these are not suitable, by themselves, for the electrically noisy environment of a boat.
So here you see the cosel unit attached to a small PCB that has suppression devices.
There is a 17 volt suppressor diode, that kills any voltage spikes above 17 volts, and a capacitor that kills anything else nasty on the supply.
The circuit.
The small resistor was added later to limit the inrush current charging the capacitor when the switch operates.
The whole driver in its case.
The case is 40mm x 30mm x 20mm
These are the switches I used next to the locker doors to turn on the lights automatically when the locker is opened.
Mounted so that when the door closes it presses the metal lever and opens the switch. There is one switch on each door, they are wired in parallel so that either door opening turns on the lights.
This is a view from inside the locker. you can see the second switch, underneath the block of wood that holds the door stay. You can see the wires from the switch joining up with the wires from the other switch and connecting to the PSU. One of the three LED strips is lit up, and you can just make out the connector block that provides power from the boat’s lighting circuit.
Parts list
- PSU 1.5 watt RS 130-750 £12.71
- PSU 3 watt RS 136-584 £15.80
- Suppression Diode RS 812-9266 £6.40 (for 20)
- Capacitor RS 839-2177 £3.23 (for 5)
- Resistor RS267-1676 £0.23 (for 10)
- PCB RS 433-832 £14.11 per sheet
- case RS 373-2328 £1.24
- Switch RS 515-757 £3.59
- TOTAL for 1.5 watt unit £22.80 includes two switches
- Prices right June 2020
Note: some of the RS parts numbers have changed since I originally specified this. I have updated where possible.