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751  Using Arduino / Project Guidance / Re: wireless sprinker system control on: June 25, 2011, 11:14:50 pm
I'm sorry, I screwed up.  I DID use the  SWADJHV (I actually went and checked it just now).  I forgot that I switched to that one when I had rectified the voltage and saw how much it was.  Yep, it was 25 bucks and I had to get two of the darn things.  However, finding power somewhere, and somehow getting it through the wall to the thermostat was a bit daunting when I already had the 24 volt supply for the old thermostat right where I needed it, so the cost was the lesser factor.  I actually dropped them a note and asked if the other one would work on rectified 24v and they suspected it would for a few hours and then go up in smoke.  They did suggest that I could use a resistor to drop the input down to 27 or so, but I didn't want another heat source inside a thermostat.

I used diodes, they were rated around 600V at an amp, I arranged them in a bridge and used a cap on the output of the regulator just in case.  I used the same diodes across the relays to suppress spikes, I got them surplus somewhere in a hundred lot and have been using them for years for various things.

So, another idea for you.  There are a ton of little 5V supplies out there for less than 3 bucks designed for powering an iPad.  I have a bunch of these around the house doing various things.  However, they won't run your sprinkler solenoids so a little relay like the ones you already have is the perfect solution to that problem.  I forgot about these devices because I got all caught up in the 24v transformer solution I already did once.  The iPad supplies have a two prong plug on one end and USB on the other.  They are reasonably easy to open if you want to just solder wires inside and run them out.  Or, of course, you can scavenge and USB cable or grab a plug off something that you aren't using anymore.  Some of the supplies have removable plugs that you can plug a regular laptop cord into and make it easy to get AC power into it.  This is the kind of thing I have used. 

Notice how the wall plug part comes off?  They say they'll supply regulated 5V @ 2A and I know for a fact they will do 1.5 amp reliably.  I've seen them for as little as 2 bucks on ebay.  That's the price range where I stock up on them.

One thing to watch out for though, some of the USB cables won't handle over 500ma of current.  I've fallen into this trap a couple of times using these little supplies, so a couple of wires is not a bad solution.

The wall wart solution is not even close to elegant as the SWADJHV device, but it is cheap and works really well for me.

I'm really sorry I screwed up on the regulator, it sometimes gets confusing when you're working from memory on some of these projects.  I'm glad you caught my mistake.
752  Using Arduino / Networking, Protocols, and Devices / Re: Adafruit's Xbee adaptor or xbee shield ? on: June 25, 2011, 05:05:07 pm
Personally, I stay away from the shields.  They force you to use pins 0 and 1 for comm and I want those for other things.   They may take up other pins that I will want to use.  One of the boards like the adafruit one give you the flexibility to put the xbee anywhere you want when you go to an enclosure, they regulate the voltage separately and they can be hooked to something besides the arduino if you want.
753  Using Arduino / Installation & Troubleshooting / Re: Mega 2560 bootloader revised? on: June 22, 2011, 01:52:00 pm
I used a binary editor to find where the problem was and then matched it somewhat to my code to find the problem.  Really a painful process.  In my case it was a data table I had that had the same value in about 6 entries.  Easy to fix, hard to find.  I don't have a clue if there is some other workaround.
754  Using Arduino / Installation & Troubleshooting / Re: Mega 2560 bootloader revised? on: June 20, 2011, 12:42:14 pm
I'm just updating this for those folk that are hoping for a resolution.  I have NOT been in contact again with the developer; I didn't want to drive him nuts.  However, checking the source file online, there has been work done on this problem.  I suspect a solution is getting closer every day. 

I'll wait a couple more days and then contact the developer again and see how it's going.
755  Using Arduino / Project Guidance / Re: I need a Project on: June 19, 2011, 04:29:08 pm
You'll have a tiny problem with the language, it'll take about 2 hours to start thinking small.  Physically, get a little door, like a pretend doorway, don't try to fit this to a real door; it'll be expensive.  A little door that you can display for the instructor will impress them and lower cost.  You'll want to look at some sort of solenoid to manipulate the locking mechanism, folks here can come up with a thousand ideas as you progress. 

But, and this is important, the folks here will help you a ton, but you have to start the process.  Figure out a door and then ask for suggestions on how to automate the lock.  You'll get about a thousand ideas.  If you don't take the first step, they'll write you off as a poseur.
756  Using Arduino / Project Guidance / Re: I need a Project on: June 18, 2011, 11:05:29 am
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You can complicate it by adding local (to the door) control.  As a person approached the inside of the door it senses them and unlocks.  If the person is under 4 feet tall it won't unlock (pool protection).  It autonomously locks at a programmed time to set the house for night.
That kind of thing.
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These are really good ideas that will help the project become more complex. Could you please list what i would need to complete this system?
This is where the 'project' part of it comes in.  I would suggest sonar to sense the presence of a person and infrared to test their height.  However, one can use sonar alone placed properly on the door and used only for short range.  Time is easier, a simple real time clock and a menu interface to the TimeAlarm library would do that. 
757  Using Arduino / Installation & Troubleshooting / Re: Ethernet shield + arduino 2560 Program issue on: June 17, 2011, 11:20:57 pm
Two possibilities come immediately to mind.  If you're using some form of Unix, there is a timing problem with the 8U2 chip and you will probably need to update it.  You could have three exclamation points in a row somewhere in your code; that stops the bootloader and you will have to find them.  Alternately, you could be suffering from a watchdog timer problem if you have one enabled.  If a watchdog timer fails you have to power cycle the board before you can reload it.  If everything works ok with the board removed, you may have a problem with the new reset circuitry on the ethernet board. 
758  Using Arduino / Project Guidance / Re: I need a Project on: June 17, 2011, 10:42:12 am
You can complicate it by adding local (to the door) control.  As a person approached the inside of the door it senses them and unlocks.  If the person is under 4 feet tall it won't unlock (pool protection).  It autonomously locks at a programmed time to set the house for night.
That kind of thing.
759  Using Arduino / Project Guidance / Re: Elbow rule help on: June 16, 2011, 09:39:04 pm
I've seen them on laser levels at homeowner stores.  I have one somewhere.  Basically they are a laser that passes through a lens that makes the beam into a line.  The line is actually fun to play with.  To sense it get a sensitive photoreceptor.  I bet some of the folks on here can suggest something.  If you could go infrared, there would be less interference, but you couldn't see it.  IMHO, seeing it is part of the fun.

Actually, you could put a reflector on them that is roughly the same color as the laser and it will light up like a spotlight when they cross the line.  Similar to what happens when you point a red laser at the tail light of a car.

google laser levels and go from there for a ton of ideas.
760  Using Arduino / Project Guidance / Re: I need a Project on: June 16, 2011, 08:24:10 pm
And I thought I was getting risque with the bar stool........
761  Community / Bar Sport / Re: Your latest purchase on: June 16, 2011, 04:40:42 pm
Wow bld, you could be living next door to me!!  Your description is exactly what one of my neighbors was saying a few days ago.
762  Using Arduino / Project Guidance / Re: I need a Project on: June 16, 2011, 01:36:16 pm
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@Draythomp, any suggestions for  a sex & Arduino-project ?

Uh, I could probably go on for about 40 pages with that one.  Wow, one that I can actually put on a pubic er, uh public board?  How about:

A sensor that you install in a bar stool that senses the temperature of the person sitting there.  It would have to be capable of fractional changes and allow for movement of the persons posterior section.  It would have to respond very quickly and have some kind of indicator that is discreet but still easily viewed.  That way as you use your various lines on the target human you could quickly see the affects.  Higher temps and you're working it; lower temps and you struck out. 
 smiley-cool
763  Using Arduino / Project Guidance / Re: Global variable values rest? on: June 16, 2011, 01:14:06 pm
Ok, one last try.  the String routines use malloc, calloc and free to manipulate strings.  Some of them are pretty intense since the String you get back is not the String you sent.  So, a memory problem can happen regardless of the size of your program if you manipulate things in some fashion.  There are calls you can find in the playground that can be interspersed into the code at various spots to see how much memory you have left at any given point.  For example, each time you add a character to your String to be parsed, you are likely to have a malloc, memcpy, free combination just to add a character at the end.  If you are receiving a hundred characters, that's a hundred of those.  Memory fragmentation happens and although the String routines have been heavily used, there could still be something that is messing with you.

Also, you can check in your loop or somewhere else appropriate to see if the variables get reset and print something.  You can scatter serial prints around various things to see what is getting you to the point where it is cleared after it is set by your get.  Heck, you can serial print the darn line numbers if it gets to that point.  I know I have when nothing else seemed to work.
764  Using Arduino / Project Guidance / Re: Elbow rule help on: June 16, 2011, 10:51:18 am
A reflective band on the arm just below the elbow, one of those lasers like they use on automatic levels that will trace a line and then sense the reflection of the band when it crosses the laser line.
765  Using Arduino / Project Guidance / Re: I need a Project on: June 16, 2011, 10:44:53 am
Listen to AWOL.  Tell us what YOU are interested in, cars, sex, home automation, sex, sunspots, remote monitoring, baseball, automatic trashcans, or maybe sex?  There are projects that you'll be interested in for about five minutes but to do something big and keep with it you have to want to do it.

For example, I've been fighting with a stupid garage door I constantly leave open.  When I leave it open the ground squirrels get in and tear stuff up.  So, a project around garage doors would be good for me.  This sounds trivial but suppose it needs to sense me leaving the property and shut the door automatically?  Or needs to be checked from the corner bar (16 miles away).  Or alert me because a squirrel ran in while I was backing out?  A robot sentry armed with a pellet gun to take care of the little critters.  Any problem can be as complex as you want to make it.

Even if all you do is listen to an iPod all day there are projects around that.  FFT (google it) to do a light display.  LED laser show with fast mirrors to trace the lights around the room.  An arduino orchestra conducted by you waving a wand antenna around.  Heck, an air guitar that senses your hand movements and plays rock cords in sequence. 

If you have a disabled friend, a wheelchair sensor that looks out for objects.  An ultrasonic cane for the blind that beeps for objects at a distance.  Extreme magnifying glasses that have a ccd camera in them and tiny displays for reading the paper.  A hat that senses when they might hit their head and alerts.

So, what do you think about when you're not thinking about sex?
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