Archive for the 4. Analog Input-Output Category

Analog input-output

Posted in 4. Analog Input-Output on October 19, 2009 by Rohit

For the diffusion of light I used the water container of a small plastic water gun (if you went to activities fair you probably received one or a shot from one thanks to International Students Union 😛 ).

The video first:

Wiring for Dummies: Understanding your tools

Know what the Arduino board does and what everything on it is for! It’s not difficult, there isnt that much on it but be sure to understand the importance of all the different inputs. This problem was based off of a very simple problem, I was plugged into the wrong inputs when trying to control analog signals. Hey its the simplest problems that bring down buildings right? Well make sure if you want an analog signal, get into one of those PWM holes.

Ok thats all I really got for tools, everything else is understandable but I wanted to mention a couple other points for beginners that came in handy for me. Analog works funny in that the actual values of the signal are weird and hard to understand. Best way in the beginning is to constantly use a Serial.println(analogValue) to just find out where you are. A very helpful trick for coders and now wirer-ers (probably not the correct term…).

Analog and Humidity Sensor

Posted in 4. Analog Input-Output on October 17, 2009 by lukekambic

The LEDs are rated for 1 watt and they’re attached to a heat sink with epoxy. One is near-UV, around 403 nm (it came from Dealextreme). They’re switched with small bipolar transistors and powered with a 6 volt 800 ma transformer. I stuck everything in a lantern hanging in my front yard and had it running the alternate-pulse program as a beacon for visitors.

I made a sensor that detects humid air by soaking a paper towel in salt water and letting it dry. I pulled the layers of 2-ply paper apart and stuck one layer between two squares of old brass-plated window screen with terminal wires soldered on. A plastic laundry clip applies constant pressure to the sandwich.

The sensor’s baseline output varies widely depending on the ambient humidity, so I connected the output to the center pin of a 10 kilohm potentiometer. One of the side pins was connected to ground, and the other was connected to a transistor base to amplify the signal before passing it to an Arduino input pin. The digital output goes from high to low at a certain point when turning the potentiometer from the position nearest the input pin toward the ground pin, which represents the point of maximum sensitivity in the current atmospheric conditions. It probably wouldn’t be hard to do this automatically in the code.

It’s surprisingly sensitive- the draft of my weakly humidified forced-air furnace turned it on from across the room. The video shows it in use as a digital input. The air in the room was fairly dry so the reading went from high to low quickly each time I stopped breathing on the sensor.

Sketches: Arduino Sketch: <a title=”Arduino Sketch: Luke_Analog_I:O_1″ href=”; target=”_blank”>Luke_Analog_I:O_1</a>

Arduino Sketch: <a title=”Arduino Sketch: Luke_Analog_I:O_2″ href=”; target=”_blank”>Luke_Analog_I:O_2</a>

Arduino Sketch: <a title=”Arduino Sketch: Luke_Analog_I:O_3″ href=”; target=”_blank”>Luke_Analog_I:O_3</a>

Arduino Sketch: <a title=”Arduino Sketch: Luke_Analog_I:O_4″ href=”; target=”_blank”>Luke_Analog_I:O_4</a>

All of my schematics are in one PDF, which I’ll post shortly.


Posted in 4. Analog Input-Output on October 1, 2009 by Frank Scarola


Arduino Sketch: pulse


Arduino Sketch: color_mixer


Arduino Sketch: color_mixer___pulse


Arduino Sketch: potentiometer___lights

Light Box

Posted in 4. Analog Input-Output on September 29, 2009 by Matt Z

Arduino Sketch: matthew_aio_pulse

Arduino Sketch: matthew_aio_mix

Arduino Sketch: matthew_aio_pulsemix

Arduino Sketch: matthew_aio_prvalues

Assignment 4

Posted in 4. Analog Input-Output on September 28, 2009 by Maria Freitas

Part 1. Pulse

Arduino Sketch: Maria_Pulse

Part 2. Mixer

Arduino Sketch: Maria_Mixer

Part 3. Pulsing Color Mixer

Arduino Sketch: Maria_PulsingColorMixer

Part 4. Value Limits


Arduino Sketch: Maria_ValueLimits

Assignment 4

Posted in 4. Analog Input-Output on September 28, 2009 by zhixunhe

For part 1, I programmed two leds to increase their brightness from off to the brightest and gradually decease to off. For part 2 and part 3,  I just made the standard circuits.

For part 4, I used a photoresistor as the sensor and keep track of the lowest value and highest value it receives.  The video I uploaded blurred and did not show clear display. So I wrote down the experiment results: the lowest value was 14 and the highest value was 45.

Part 1 “Pulse”:

Arduino Sketch: Pulse

Part 2 “Color Mixer” :

Arduino Sketch: ColorMixer

Part 3 “Pulsing Color Mixer”:

Arduino Sketch: Pulsing Color Mixer

Part 4 “Finding Sensor Limits”:

Arduino Sketch: Finding Sensor Limits


Posted in 4. Analog Input-Output on September 25, 2009 by danrapoport

My post is especially non-spectacular, yay archie + crew schedule!





Arduino Sketch: Asst4_4

Arduino Sketch: Asst4_3

Arduino Sketch: Asst4_2

Arduino Sketch: Asst4_1