The Idea
Update: Looks like somebody had this idea before me and made a product out of it. Just Google Fake TV. In fact, you can also buy a clone of this from Ali Express – again, just search for ‘fake tv’ in Ali Express. The Chinese versions can be had for about $12 in your hand and that includes a power supply (no doubt of somewhat dubious quality and safety standards). So what follows is a fun project, but it’s easier and possibly cheaper to buy direct from China.
The idea of leaving a light on at home while you’re out is to give the burglar an uneasy feeling that somebody’s at home and it might be worth trying the next house along instead. A TV on at night plays a constantly-changing light-show against your window which really does say I’m at home and I’m awake. Of course, you could leave a real TV on but that’s an eco-disaster since TV’s consume 50W at best and hundreds at worst. Plus you might not want to be burning your TV in for days on end if you’re not at home.
Why not use some of these neopixel RGB LED’s and a microcontroller to simulate the same effect? With just a few Eurodollars, an hour of build time and a power budget of 5W absolute maximum, it sounds like a winner
Building
I built using some of my favorite prototyping board. It’s not strip board (Vero board) so you have to solder your own wires but it’s cheap, pre-cut to commonly-used sizes. I get mine from eBay – search for ‘prototype PCB’. I had to file down the end of the board so as to not foul the USB connector on the Dig spark.
The resistor and capacitor for the neopixel WS2812B LEDs part of the circuit are on the back of the board.
I turned the little black tube for the LDR of plastic on the lathe. It occurred to me while I was making it that I probably had several tens of metres of spare black irrigation tube from which I could have snipped off a centimeter in a heartbeat. There we are, it works.
I could imagine several variations on building this. You could use any kind of Arduino with pretty much the same source code – just need to change the pin assignments. You could use fewer LEDs and increase the value of LED_BRIGHT in the code. Or just increase LED_BRIGHT. Bear in mind that these LEDs eat about 0.5W each at full brightness (in RGB ‘white’ colour). The LDR is optional. Obviously you’d need to trim the code if you left off the LDR. If you’re only going to use this for two weeks a year while you’re away on holiday, the environmental impact of manufacturing and shipping the LDR probably outweighs the tiny electricity savings of switching off the LEDs during the day.
Read More: Fake TV Security Light