For this application, we don’t need much more processing power than this very basic microcontroller.One major advantage of this particular family of microcontollers is the fact that they can run off any voltage supply from 2V up to 5.5V, without the need for a regulator. Therefore the power supply needs to be between 2V and 5.5V, you can either use 3 AA or AAA cells (3v – 4.5v), or a single lithium ion cell (3v – 4.2v).I used a 18650 lithium ion cell since I had a whole bunch lying around (you can find 8 cells in most laptop batteries). Light detection: Adding light detection allows the LEDs to only turn on when dark.


(Or a photodiode + transistor combo) When light falls on the phototransistor, a current flows, pulling the voltage after the resistor down.

The resistor needs to be sized so that there’s a decent voltage swing between light and dark that the microcontroller can detect.

I used a photodiode + transistor, with a 40k resistor. Voltage reference: This allows for low-battery detection.

So here’s a slightly less crass way of using LEDs for decorative purposes.

While this is by no means a neat and polished solution, and probably not the first of its kind, however the pulse effect is as far as I have seen unique, and exactly what I wanted.

I hope that this will inspire others to create similar.The set-up It consists of a plain, unmodified vase, and a small battery-powered unit that sits behind a vase and shines three LEDs to give some nice ambient color.The circuit is powered by a microcontroller, in my case, a PIC12F683, I’ve included source code for the PIC12F683, but presumably it can easily be ported to Atmel or other microcontrollers.I am writing this instructable for those with experience with circuits and microcontrollers, I am happy to answer any questions anybody has. The brains – this will control the LEDs and produce the colours and pulses of light 2. The circuit diagram is below, there’s also a PDF with the same diagram since the picture is a little small and blurry.The power – I use lithium-ion cells, but the circuit works perfectly well using 3AA or AAA batteries typically this will run the circuit from a week up to a month depending on battery. Light detection – this is so that the circuit turns on only when dark 4. You will need: – PIC12F683 or other microcontroller – either 1x 18650 or 3x AA – 220u F electrolytic capacitor (or any value larger than 1u F) – 10k resistor + zener diode (or 1N4001, see later) – 3x 150R resistor, 3x NPN transistors – 3x high-intensity LEDs, 3x 20R resistor (see later) – 40k resistor, phototransistor 1.Voltage reference – this is needed for low-battery detection, for lithium-ion cells, this is important since over-discharging damages the cells. The circuit is powered by a PIC12F683, which I favour for its small footprint (8-pin package).

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