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Topic: Solar powered LED light sculpture (Read 8818 times) previous topic - next topic

Hi, I need advice on a sculpture I am in the process of making. 

It will be installed in a park at the end of the month, and I am working on the electrical components of it.   My electronic knowledge is very limited, which is why I am seeking the help of those much more knowledgeable than I.

The sculpture is made of plexiglass, and sits on top of a metal base.  The plexiglass will house the 12v LED light strip I have, and the metal base will house the solar charger + battery + arduino.  Basically, I would like a part of the metal base to be interactive so that when someone touches it, the brightness of the lights change.  I've looked at so many tutorials, articles, etc. and I am really struggling to understand how to set up my arduino and how to power the whole set up.

I have: LED light strip, arduino, capacitative switch.
Need: solar panel, charger, battery, other components to make the circuit work

Any input at all would help!

To be more specific, I've got:

12v LED light strip (energy consumption per ft: 1.44 Watts / 120 mA)
Arduino Uno
Capacitative switch (MPR121 Capacitive Touch Sensor Breakout Board)

rutierut

#2
May 01, 2014, 03:47 pm Last Edit: May 01, 2014, 04:09 pm by rutierut Reason: 1
Hey, looks like a cool project!

unfortunately i'm a noob to but maybe this helps: http://www.instructables.com/id/DIY-Touch-Sensor/

It looks to me like this would work, just let the Arduino change the value it outputs once the pin is LOW

And i think but again i'm a huge noob that if you set an pin as input and connect it to the metal plate, but with a huge resistor in-between, and you connect 5v to the plate it would work to but then again i'm a noob.

vtrguy

Personally, I would use the capacitive sensor to trigger a SWITCHCASE and have different brightness set to the LED strip. You need to figure out what you want the display to do... Immediately jump to the next value? Fade into it? Will it be doing anything without input? Are the numbers going to be preset or random?

You should use a high power transistor to switch the brightness for the strip (IE. TIP122).

I'm not very familiar with the MPR board, however the principle is the same in the sense that the input (The base of the art) should have a wire connected to it and it should go to one of the pins on the breakout board and that will be the sensor.

https://learn.sparkfun.com/tutorials/mpr121-hookup-guide/capacitive-touch-sensor-breakout-board

I'm unsure of whether the board has an autocalibration for sensitivity as such a large sensor will be prone to feedback/false readings so that may take some debugging come time to run.

If you're going to be using an Arduino Uno, the regulator onboard should be okay for your input of 14v from the solar panel so you shouldn't need to fiddle with any regulators. However, for longevity, it may be prudent to stick a larger regulator to avoid prolonged high voltage, a +12v regulator can be had for a few dollars in a TO220 case.

As for the battery, you need to figure out how long you'd like the project to be running to determine the power required.

Will it be on all night long? Just the day time? Anywhere in between?

CrossRoads

Quote
You should use a high power transistor to switch the brightness for the strip (IE. TIP122).

Disagree - PWM output thru 220 ohm Resistor to the gate of an N-channel MOSFET, let  MOSFET switch - from LED strip to GND. + of LED Strip to 12V.
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