Hacking an IKEA MOLGAN Light - Part 2

Over a year has passed since my previous MOLGAN Hack to improve battery life, (see http://blog.ambor.com/2017/02/hacking-ikea-molgan-light.html). I have modified several MOLGANs and the battery endurance in the modified lights is great (several months on rechargeable AAA batteries). Under the default timing, the lights come on for about 30 seconds which is fine for all of them except one which I'd like to stay on for a little longer.

As mentioned in my previous post, these lights are driven by a very common BISS0001 motion detector IC. Pins 3 and 4 are connected to resistors and capacitors whose values define the "Output Pulse Width" which is the fancy way to say the number of seconds that the light stays on once it is triggered.

Refer my previous post to see how to disassemble the light. Once you are inside you will see what is pictured here (ignore the extra RED and BLACK wires in this photo). I have drawn on my board so you can see which are the relevant resistors and capacitors to adjust the timing. I've also drawn a black trace line to show how they are connected to each other and via a pad labeled B.

The pulse width is defined by a function that is the product of the resistor and capacitor value. If you increase them, the time increases and if you decrease them the time decreases. In my case, I wanted to increase the time and the easiest way to do this was to remove the old resistor at position R11 and replace it with a bigger value. In my case I went for a 1.5 MΩ resistor which gives me about 80 seconds of ON time. If you want to reduce the on time from the default then simply put a resistor in parallel (piggyback) with the one that is already there.

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