Intro: IKEA Bäve LED Spot Hack
I bought this lamp a few years ago, but never used it since the light was way too bright. Furthermore the transformer made an annoying buzzing noise, which may have been resolved since then ( or maybe not, see: https://plus.google.com/+FelixWatts/posts/3JLNaan...
This instructable demonstrates how to modify the lamp using an Arduino and some electronics, so neither brightness nor noise is an issue anymore.
Attention: though all modifications are done to the low-voltage (12V) part of the lamp, you will still be messing around near mains voltage, which as always is dangerous.
Step 1: Design and Build the Test Circuitry
These are the basic components you need:
- IKEA Bäve lamp
- Arduino Nano
- Buck converter 12V -> 7V
- N-channel MOSFET transistor with low power dissipation (low R-DS). Alternatively multiple transistors in parallel (I am using 3 IRF520)
- Push button/micro switch
- Capacitors 1000uF and 10nF
- Resistors 220Ohm and 10kOhm
Step 2: Build Test Setup
When you assemble your electronics beware that
- You could possibly leave out the buck converter, and run the Arduino straight of 12V (perhaps with a few diodes in series to lower the voltage a bit). I initially experimented with a LM7805 but I was not comfortable with the amount of heat it dissipated
- A N-FET is used to turn the LED spots on and off at a high rate. Depending on the type of FET, it can get rather hot. To avoid this, I am running 3 FETs in parallel. Even 2 FETs in parallel gives a dramatic reduction of the heat dissipated compared to using only 1 (P=I^2*R, so reducing the current ‘I’ by 50% or 66% has a significant effect)
- This circuitry shown is the end result of some experimenting and monitoring signal levels with an oscilloscope. None of the component values have been properly calculated, so you may want to double check things.
Step 3: Software
The software can be downloaded from here: https://github.com/LarsWH/arduinoLedSpot
Some features of the software
- The light level increases and decreases as long as you press the button
- The selected light level is stored to EEPROM only when you release the button
- When powered on, the light ramps up to the selected level. There is unfortunately a boot-delay (could possibly be reduced/removed through some more hacking)
- There is prell detection in the software. This is possibly not needed.
Step 4: Assemble the Final Hardware
When you construct your PCB keep this in mind:
- It has to fit into a narrow housing. Ardiono Nano is well suited. My ESP8266 board would be too wide.
- The building height is also rather low.
- Ensure the bottom side of your construction is fairly smooth (no sharp or pointy objects) to avoid short circuit when mounting inside the lamp
Step 5: Mount the Micro Switch
Drill a hole in one end of the lamp and mounted a discrete micro switch.
Make sure to locate the switch so it will be clear of the mounting frame when assembled.
Step 6: Make Room for Your Electronics
Depending on the length of your construction, you may have to move the Bäve transformer a bit to fit everything in.
The transformer is mounted with double adhesive tape, and you will need a long thin object to push in under the transformer. I used a saw blade.
Step 7: Mount the Electronics Securely
Add 3-4 layers of insulation tape to the Bäve mounting frame (bottom and sides), to avoid any short circuit. Then place the electronics in the mounting frame, and tied it down with the same type of insulation tape.
Make sure you mount the Arduino in a way, that you can easily connect a USB cable for software updates.
Attention: make sure that the mains cord is properly secured before assembling the lamp again. Use a cable strip or tie knot or something.
Step 8: Mount the Lamp in the Ceiling and Enjoy
I am operating the lamp at one of the lowest steps, probably meaning less than 10% of the power it is delivering when you buy it from IKEA.
At the lower levels the annoying noise from the transformer cannot be heard at all. The noise comes back gradually at at higher levels.
Notice: if your mains connection has a dimmer feature, you may experince strange behaviour, like the lamp shutting off shortly after power on, or perhaps not turning on at all. I had to reconnect my lamp and get the mains from a line without any dimmer function.