Under Kitchen cabinet LED strip lighting

[Radian]

I Decided to fit some new LED strip as the twin RGB tapes I put up a long time ago are very inefficient for the white that we most often use. Over 120 Watts! And the family like to leave it on all day! I was very pleased with the new 3000K white but coming down to the kitchen the following day most of it had peeled off...

 

Now that was a surprise because I had spent the longest time cleaning the underside first with wet wipes then with IPA on paper towels. My theory is that the melamine covered chipboard is just too glossy - rather like the backing tape that protects the sticky surface and you peel off before pressing into place. So my second attempt involved 80 grit sandpaper and more IPA to get the dust off...

 

 

Nice and matte, ready for another attempt at sticking it up...

 

 

Only time will tell if it stays up now. So far it's been up for two days and no sign of peeling.

 

This might be a tip for people thinking of using self-adhesive LED tape like this.

[Radian]

While it's more efficient than the coloured lighting it still draws 70 Watts. Usually on for around 15 Hours each day.

 

1.05 kWh

30.45p a day

£111 a year 😮

 

People never switch it off when leaving the room and TBH the kitchen does look dull when viewed from other places in the house when not lit.

So what I want is something I saw in the first blade runner movie - Deckards kitchen lights dim up when he enters the room.

Dimly lit when unoccupied, fade up to max in around one second when you walk in, stay on full until room vacated then fade down over a minute or so.

 

Easy to find a PIR on/off control but nope, not a two-level dimmer controlled by PIR.

Time for a hack then! 12V PWM dimmer, PIR module and some diodes, resistors and capacitors...

 

[Radian]

Success. In case anyone's interested here's the schematic of the reverse engineered Dimmer plus the handful of components I added to enhance its functionality:

 

 

The original PCB had an unused half of a LM358 OPAMP which I've used to buffer the PIR module output. All the additional parts can be tacked onto the PCB in various places. The Rotary level control now sets the minimum brightness which the lights fade down two after a minute or two of nobody being in the  kitchen (adjustable with choice of R101) and Full brightness is obtained within one second of someone entering the room (adjustable with R102).

 

This is with the PIR module set to minimum on-time but this is also adjustable on the module. I will turn this up to five minutes or so when the novelty of playing around with the new feature wears off 🙂