Instructables
I'm a fan of LEDs, lots of LEDs.  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.


 
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Step 1: The Circuit: overview

The circuit can be split into 5 parts:
1. The brains - this will control the LEDs and produce the colours and pulses of light
2. 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.
3. Light detection - this is so that the circuit turns on only when dark
4. Voltage reference - this is needed for low-battery detection, for lithium-ion cells, this is important since over-discharging damages the cells.  For AA or AAA batteries, this is less important.
5. LEDs!

The circuit diagram is below, there's also a PDF with the same diagram since the picture is a little small and blurry.

You will need:
- PIC12F683 or other microcontroller
- either 1x 18650 or 3x AA
- 220uF electrolytic capacitor (or any value larger than 1uF)
- 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

circuit.pdf(842x595) 17 KB
coldmow3 months ago

Very nice, easy and logical. Beautiful!

RodgerE13 years ago
Very nice. I've been wanting to do something similar but haven't had the time.
ChrysN4 years ago
Ooh pretty!