Show Posts
Pages: [1] 2 3
1  Community / Gigs and Collaborations / Re: doors and windows status detection and sms to phone on: April 03, 2013, 11:35:58 am
It is pretty easy to detect the state of door/window embedded switches with an arduino.  Wiring (or wireless communication) between the switches and the arduino would be the hardest part.  The rest is clearly possible, but needs to be fleshed out before anything can be designed.

It is probably possible to send SMS messages via some internet service, such as Skype.  For that, either a wifi or ethernet shield might be appropriate.  I suggest a wired connection unless you *must* use wifi.  Alternatively, a gprs shield could connect directly to the a cellular network to send SMS messages.  As another alternative, you might post messages to Twitter or similar.

You'll also have to figure out what messages you want to send where under what circumstances, and how you would update these rules once programmed.  Will you need to receive messages, or take any local action besides passive monitoring?

To address these kinds of questions, you might imagine that you are about to purchase an off-the-shelf product that will do what you want.  Write a user's manual for that imaginary product.  I offer that as the first of your step-by-step instructions.
2  Community / Gigs and Collaborations / Re: Need arduino builder for simple project on: April 03, 2013, 10:57:39 am
Here's a simple, inexpensive alternative that requires no arduino or programming:

1) Pick up a rotary timer switch in a drug store, the kind folks use to switch their lights on and off at various times while away.  Plug the soda machine into it, and set it to be off during the hours you want.

2) In parallel with the light timer, wire an interval switch that the clerk can activate.  These are usually rotary, not pushbutton, but might work OK for you.  They are commonly used to turn on spas or saunas or microwaves for a selected interval.  Two minutes is pretty short, so may be hard to find.  Worst case, you could just use a simple toggle switch and have the clerk switch it off after the customer gets his soda.
3  Community / Website and Forum / What Time Does the Forum Think is Now? on: April 01, 2013, 11:02:43 pm
Posting dates/times are shown for messages, but they're obviously not for *my* time zone.  It would be helpful to know the forum's current time for comparison.
4  Community / Gigs and Collaborations / Re: WILL PAY FOR SOMONE TO DO A VERY SIMPLE PROJECT FOR ME on: April 01, 2013, 10:35:26 pm
Help us understand your need better.

As best I can tell, you already have a device that attaches to a gprs shield and captures messages from it.  However, you must be physically present to read the messages and delete them.  There is no Arduino involved.  Is that correct?  Can you identify the device you are using?

You would rather have a copy of received messages relayed to your phone, either automatically or on command from you.  You would also like the ability to delete some or all messages, freeing up space for more.  Is that correct?

If you use an arduino, you may not need to retain the message storage device you are already using.  The arduino could store, forward, and delete messages as needed via the gprs shield.  Maybe you want to keep the device for whatever user interface it has, or maybe use an alternative arduino-controlled interface.

Am I on the right track here?
5  Topics / Product Design / PCB Etch/Drill + 3D Printer + CNC/Router + Plotter ~$700? on: April 01, 2013, 07:51:31 pm
I am impressed with the possibilities of the "Core XY" platform described at  In short, it is a simple, rugged, inexpensive, compact way to move a small, flat platform in cartesian space.

Once you have the above, you need a couple more pieces to do useful work:

1) A tool to mount on the XY platform.  Interchangeable tools such as Dremel/drill with bits for etching, drilling, routing, etc., or a heated extrusion head for 3D printing, or a pen or marker for plotting.

2) A work surface to be processed.  In the simplest case, such as a plotter, this can be just a flat work surface below the pen.  Simple pen-up/pen-down control could be in the tool head.  For more general work such as 3D printing, you must add z-axis motion to either the work surface or the XY platform.

You would doubtless wind up with an Arduino controlling the X/Y/Z motors and tool head.

I'm reluctant to shell out $1000 for a cheap 3D printer, but toss in PCB fabrication, fancy woodworking, drawing and cutting, and I'm in!

I'm hoping some others will be inspired to chip in designs for tool heads and a Z-motion mechanism.

To start, I propose the XY platform could be made a little simpler and cheaper by eliminating its precision shafts and bushings.  Instead, constrain vertical motion of the X and Y sliders with a small lip of aluminum plate above and below, with about 0.001" shim to reduce friction.  The lips could either be attached to the sliders or the slidees, with lubricant in the slots they form.  What do you think, mechanical experts?  Would that work OK?  Would wear on the aluminum plates be a problem?
6  Community / Exhibition / Gallery / Re: arduino enclosure using plexiglass for the X10 webserver on the arduino on: October 22, 2012, 09:26:00 am
A very nice mini tutorial on controlling arduino via the web, including your smartphone.  Useful for lots of applications!
7  Community / Exhibition / Gallery / Re: Arduino's in permanent projects? on: February 19, 2012, 03:40:06 pm
I have two - one with a real Arduino board and one with Atmega 328P with bootloadeer.

The first is a whole house telephone intercom system.  Description is at

The second is a vent controller added to my home HVAC system.  In that case, I wanted to power the controller with the 24VAC that operates the HVAC controls.  It was easy, compact, and economical to just plop the 328P into my custom circuitry.

The second system activates duct dampers and the furnace fan to automatically draw outside air into the house during cool Summer nights, and occasionally during warm Winter days.  When I awake on a Summer morning, the house is usually luxuriously cool, but never cold.  The house seldom heats up enough before evening to trigger the air conditioner anymore.
8  Topics / Robotics / Spherical Flying Machine Anyone? on: November 19, 2011, 04:40:01 pm
Here's a demo I thought might interest you.  Anyone want to try this at home?
9  Community / Exhibition / Gallery / Re: Pico85 SMD Arduino compatible (ATtiny85) on: September 16, 2011, 01:39:39 pm
I like it!

I would like it even more if it could be attached to a USB cable and programmed like a normal Arduino with bootloader.

Maybe an external "helper" board could perform this function? 

Come to think of it, it would be great to have such a board that could program any of the Atmel chips via Arduino IDE USB connection without a bootloader on the target chip.
10  Community / Exhibition / Gallery / Re: Wall Plotter, the Frankenbotic Thinganator, Alpha test on: May 15, 2011, 01:49:06 am
If you're looking for code to "vectorize" images, you might explore software developed for the RepRap project.  (See

RepRap is a home-buildable 3D printer that uses a plastic extruder head (rather analogous to a plotter pen) to build up parts layer by layer.  Here's an overview of how I *think* it works:

1) Host software on a PC "slices" a 3D model into layers.  Presumably, each slice is a (black/white) bitmap image.
2) Each slice is vectorized by translating it into a series of "gcodes".  The gcodes specify extruder head moves.
3) Gcodes are fed serially to an Arduino based gcode interpreter which, in turn, activates steppers to move the extruder head and turn extrusion on and off.

I understand gcodes have their origins in specifying geometries for PC board layout.
11  Community / Exhibition / Gallery / Re: Wall Plotter, the Frankenbotic Thinganator, Alpha test on: May 06, 2011, 10:51:46 pm
I like it!

I have thought for years about coming up with some sort of large dot matrix printer gantry that could paint murals on walls.  You have identified a wonderfully simple and inexpensive approach.  I wonder how the dry erase markers would work on painted drywall?

Well, unless the "mural" is going to be a single color, single continuous line affair, you need a little more:

1) A way to pull the marker off the wall while moving it.  A third, "lifting" stepper and line might accomplish this.
2) A way to accommodate multiple colors.  Mounting them sequentially might do the trick, if reasonable alignment can be achieved.
3) Software to parse and scale an image, and translate it to mechanism moves.

While there are lots of ways to do this with more complexity and varying degrees of performance, I applaud the elegant simplicity you describe.

12  Community / Exhibition / Gallery / Re: Pseudo Theremin on: February 09, 2011, 08:05:12 pm
How about a theremin on steroids that could be played with one hand?

Instead of sensing the distance of two hands separately, why not sense the distance and left-right position of one hand simultaneously.  Distance could then control volume, while left-right controls pitch.

While we're at it, a third sensor could add up-down to your hand position sensor.  This could control another parameter like waveform (sin <-> sawtooth) or reverb.
13  Community / Exhibition / Gallery / Re: Pseudo Theremin on: February 08, 2011, 11:37:15 pm
Nice work!

Your approach has some inherent advantages over theremins of yore.  It is more compact, easier to build, and more repeatable and predictable than analog circuits that rely on the vagaries of stray capacitance.

A couple of other improvements suggest themselves:

1) Intentional auto-tune, either in hard steps, or a softer tendency to gravitate toward in-tune frequencies
2) Selectable audio waveforms, either by manual switch, or modulated by pitch/volume signals

Maybe we'll see one of these things in next year's Super Bowl half time show.  This year's came off like an auto-tune extravaganza.
14  Forum 2005-2010 (read only) / Development / Re: LCD Touch screen and SD card expand shield on: September 18, 2010, 08:59:52 pm
Does this shield reduce power and logic levels from 5V to 3.3V?
15  Forum 2005-2010 (read only) / Development / Re: Any PCB gurus in the San Jose/Los Gatos CA area? on: September 17, 2010, 12:16:18 am
I was reluctant to use Eagle because of commercial, size and licensing restrictions.

Kicad (see ) turned out to be a very nice free suite including schematic capture, PCB Layout, even 3D PCB modeling!  I used it with good result for the commercial version of "Add-A-Com Whole House Intercom for Standard Telephone Systems."  See for a brief description.

I am close to you, in Saratoga.
Pages: [1] 2 3