James Sentman

Alpha Clock and xBee

Over the weekend I assembled an Alpha Clock Five kit from EvilMadScience.com. I have built several EvilMadScience kits and the polish and attention to detail in the execution is matched only by the imaginativeness of the design. In the interest of full disclosure the evil mad scientist in chief is responsible for my life long happy addition to good coffee...

clock hero.jpg
Those are monstrously huge and bright (though brightness adjustable) alpha numeric LED’s in there. What makes this kit special beyond just being a beautiful project is the serial port it includes and the ability to display text. A display of activity or alarm or temperature or whatever is something that I’ve often built for connection to XTension and once you get used to being able to glance up to see the outside temp or to watch for motion at the front door or whatever you’ll never want to do without. I could run a wired serial port to this, slow speed serial carries just fine over long runs of cat5. This is a TTL level serial port so a level shifter would be necessary at this end. Or with the right usb cable it could be directly connected to the computer, or through a TCP/Serial adaptor over ethernet. But more fun would be wireless via the xBee radios that I recently wrote an XTension driver for.

The clock runs at 5v so the first thing I needed was a 3.3v regulator. I succumb to the urge to work too fast and just built it as 3D solder art rather than use a board. There are dozens of places to order a project kit with a tiny board or you can buy them already made if you dont want to go that far. Both adafruit and sparkfun make xBee breakout boards with the power supply built in too, but I had these blank ones on hand so I used them.

3v regulator
the heat sink is overkill, the radio uses very little power and it barely gets warm to the touch, but in case I wanted to add more devices later to it this gives a nice comfortable amount of overhead. To the clock only 3 extra connections are necessary. 2 for power which run to the regulator and then to the xBee board and one to take serial data back from the xBee to the clock.

3 connections

I wasn’t sure if I needed to bring out the data ground as well, it worked fine without that here but if you’re in a noisy environment you may need to being that across to the power ground as well. The xBee breakout is equally simple. Power and the tx data pin connected to the rx data pin on the clock.

xBee Breakout

lots more pins for future expansion. I’m definitely going to add some various color LED’s for signaling various alert or motion states and possibly a PIR motion sensor and a temp sensor as well. But if I tried to do all that on the first pass here it would never get done. This is a very simple breakout board, the pins on the xBee are tiny and while you could solder directly to them you really dont want to do that. The radios need to be programmed by connection to the computer and removed from the socked on this board. If you were to solder them directly it would be impossible to do that.

as installed in clock
The xBee and the regulator tacked down with a bit of foam tape to the beautiful acrylic case. And then finally re-assembled. Here I’m holding it so you can see the size of the LED’s as wall as tilting it into the light so you can see the segments:

BIG leds.jpg

And that concludes the hardware portion of the project. I’ll get started on part 2 shortly with instructions on setting up the xBee with XTension, tunneling through to the serial ports on it and the scripts to send data to the clock.


XTension Updates

Been working hard on XTension updates. One thing missing from our Home Automation list of supported devices were thermostats. You could always go with an X10 or UPB enabled thermostat but the direct connecting “communicating” thermostats are the best and most reliable. I had written a program so many years ago that I can’t remember to talk to the Omnistat line of thermostats but it was never really released even though I used it here. As of XTension Beta 826 I can now directly connect to the ~$100 wifi thermostat from Filtrete/3M that Home Depot carries in their stores as well as directly to the Omnistat line of serial port connected thermostats. These all really work nicely. I am waiting on the rs485 adaptor I need to talk to the Aprilaire thermostats and have an RCS TC60-485 on order to get up and running too. That should cover the most well known communicating thermostats but if anybody has others they would like to see supported please let me know. And yes, I’m aware of the announcement from the ex-apple folks. I’ll be watching for a protocol document to appear and will support that too if it’s reasonable to do so.


xBee and XTension

xBee radios are awesome. They provide a mesh network and lots of analog and digital input and output options for about $25 a piece. For remote control and home automation and control there are some really great possibilities here! Supporting people that like to do a little soldering themselves is important to me, as I do that sort of thing... See the drivers so far as a proof of concept working now!

set the resolution to 720 to see the screen captures properly.


Garage Augmentation

When we moved I knew that the garage was smaller in the new house than the old one, but I thought somehow that it would be OK or that we would quickly be able to afford to put on an addition to the garage to house my table saw. Alas, there will not be a garage addition any time soon. First thing I needed today was a rack to hold longer stock. I’ve been buying good oak trim as they have it in stock locally till I have enough to do some projects in the kids rooms and it’s just been lying on the floor which is no good. The ladder was already stuck up with a hook to the ceiling so it wasn’t much of a stretch to do the same with the longer wood bits.

long stock rack
The two tubular steel hooks came with the garage and a previous owner I think used them to hang bikes or garden hose or something. I took them off the wall when I built those cabinets there immediately after moving in and saved them knowing they would be useful. So I just screwed them into 2 ceiling joists and screwed that angle iron onto them. Keeps the wood up over the work area and mostly out of the way. Course I wont be able to store stuff there long term as it would probably warp, but to store for a bit while I”m gearing up for a project will be fine. That 3by is necessary to raise them up enough that the cabinet doors can still open... In a tiny shop you make do with what you got.

Then against the wall there is this interesting and mostly useless bit of extra storage space. It goes up under the firs flight of stairs into the bonus room above the garage.

The previous owners had it full of empty paint cans and we just stuffed it with stuff that you could never get to. I saw an instructable of a guy who built tracks to hold up plastic bins to the roof in his garage. The roof isn’t high enough nor is there enough space to do that against the ceiling here, but I could do it in here and it would leave enough room underneath and next to them to store longer or odd shaped stuff. There is room for 4 plastic bins suspended up on tracks.


was also an excuse to use my pride and joy tool the festool domino mortise and tenon tool! These are the boards the go flush against the ceiling in there. In the middle will be another one perpendicular unto which 1x2 strapping will be attached to form the rail that the edges of the bins will hang from. The big through mortises there are carefully measured onto this board to correspond with the joists in the ceiling of the hole in the wall. When hanging I can put a big screw through with a washer on it and adjust them a certain amount back and forth to get just the right fit. The little tabs on each side are only a quarter of an inch wide so there isn’t much room for error.

Getting ready to climb in and damage my back working up over my head, close quarters and not pleasant.

And they are up! 2 plastic bins in the back and room for 2 more in front, they slide in and out really easy. Ben was impressed but really just wanted me to get them back out so that he could go through my stuff... And finally as they are now, 4 plastic bins I can actually get to easily and room to store a bunch of other stuff that was just stacked up around the garage. Very happy, but a little sore...


A Dozen xBee Radios Arrive

Yea... I guess you could say I’m serious about using these things. Having a big box of them almost makes up for the one I cooked yesterday not realizing that the pinout on the 3 volt regulator I’ve got here is totally different than the pinout on the 5v ones I’m used to... Lookup those datasheets people... In any case, xBee rocks.


115 volt DC power supply for LED holiday lights

Nobody likes flickery LED christmas lights! You can put a full wave bridge rectifier and a capacitor on them but then you’re then supplying a lot more power than they are designed for since that will be about 160 volts DC give or take and the duty cycle will be 100% rather than the 50% duty cycle of regular AC. They will likely be nice and bright for a short time before they burn out. Years ago I experimented with rectifying the output from a regular dimmer switch and this seemed to work pretty good and let you reduce the output to a reasonable level. But not all dimmer switches wanted to come on turned down so low and if they got bumped or reset by an interested child it could burn out your lights. I tried to duplicate that setup recently for a friend who’s flickery LED lights I had brought to his attention and which have bugged him since (hi Bill) and I just couldn’t get it to work anymore. I have no idea what I was doing differently. I blew up a whole box of dimmer switches which just kept burning up on me. Turns out that the rectifier I was using was damaged and was a hard short... So that explains that. But in the meantime I was doing other research and decided that the proper way to do it with less danger to life and limb was to start without about 80 volts AC and rectify and smooth that out.

80 volt transformers seem difficult to find but I did find 40 volt .25 amp ones inexpensively and so 2 of them with their secondaries in series and the primaries in parallel yield 80 volts. Which when rectified yields 115v DC which is perfect.

dangerous high voltage bench testing

.25 amps at 80 volts output might mean that this can supply 20 watts of power into strings of LED lights, which is plenty. This is a very dangerous test setup obviously, don’t do it this way. Important considerations are that the 2 transformers should be carefully wired the same polarity to the mains so that the output is in the same phase so that it adds up to 80 volts instead of unadding to 0 volts... I wouldn’t go more than 2 of these, I don’t know what the internal insulation is rated for. 80 volts doesn’t seem to be a problem but it will break down eventually if you start adding them up. That little 47uf 450v cap smoothes out the voltage very nicely. At least for this test string. The setup this will eventually go on is larger and so I might need to increase that value. I will also be adding a .25 amp fuse so that this doesn’t overheat. I don’t think it can fail in a spectacular fashion, the transformers will just heat up and eventually short themselves out and blow the fuse. I will also add a high value bleeder resister to the cap so that any voltage left in it when you turn it off is bled off safely. Not that cap will store a whole lot of power, but LED’s don’t conduct much at all once you get below their threshold and so 50 or 60 volts might stay on the cap for some time after turning it off.

In generally messing with mains voltage and high voltage is a real bad idea. I’ve got this plugged through an isolation transformer and a ground fault sensor just in case, and though it doesn’t look it from there the cord is clamped down so that it can’t be pulled off the desk and such. I’ll post more pictures when I’ve got it mounted in a nice case.

If you decide to do something like this you’ll also have to test it with the specific strings of lights you’re using. Obviously it won’t work if there is a controller or sequencer box attached. Some strings also wire some of the LEDs one way and some another way so that they are on in opposite swings of the AC. If you run those kind of strings on DC then only half the LED’s will light. There may be other dangers and issues I haven’t though of too...

UPDATE: the device as delivered:

working great, well within specs I think and making everyone happy.


Diavolino! Arrives and is instantly assembled.

Got my package of blinky blinky from Evil Mad Science today. Among the various fun LED’s and other things were the main reason for the order a couple of Aduino compatible Diavolino boards. They come in Kit form and true to form as everything from Evil Mad Science is they are just excellent kits. I would be surprised if it took me a whole 15 minutes to go from this:

To assembled, working and running the first program on them:

The Evil Mad Scientist of evilmadscientist.com and I were at college together. Well... he was in college, I was done with college but having no idea yet what to do with my life and nobody yet willing to pay me for my time I spent a lot of time at college... He made me my first Espresso and I liked it.


You CAN run X-CTU on the mac to setup XBee radios

It runs just fine with wine. Shame on the XBee manufacturer to only provide a windows binary of the initial necessary configuration and firmware update program. In this day and age with such wonderful cross platform development tools (like REALbasic, hello, port your VB code and compile for mac windows and linux!) it’s so annoying to see things that are absolutely necessary that I have to resort to this kind of mucking about. Especially with something like these otherwise terrific XBee radios that are so embraced by such a wide group of artists and makers. Enough whining ;)

XBee RadioSearching teh intertubes I found many people that were running the configuration program under windows emulation, and a few references to people who might be working on a Mac version of the program from scratch (the protocols for doing everything it does are documented, but are non-trivial to implement) but evidently everybody else who might have used wine to do it found the exercise so trivially easy for them that they didn’t feel the need to document it for anybody else ;)

First you need wine, it’s just a single binary app now, no problem. Go search and install it. The only catch is that you must also have the XWindows for mac system installed. This is an optional install on OSX, but you can find it on Apple’s site.

Once you have win and the X-CTU installer you can just open the one with the other. It will run the installer. I didn’t tell it where to put the installed app, just let it default. I still am not sure where it went, possibly into the .wine folder in my home folder but it wouldn’t show up in a search. No matter, it left a windows shortcut behind on my desktop which I can do an “open with” to pull up wine and run the program.

Some confusion exists over the installation of the drivers. If you have a XBee Programming Adaptor like that then you need to install the serial drivers on the Mac side to talk to it. In that case it’s the FTDI drivers (which as far as I’m concerned are the best Mac usb/serial devices out there, their drivers have always worked and never caused me any grief when many others have) Once thats working on the Mac side then you can setup wine to see them.

So plug in the adaptor and now you have to do some work in the terminal. This is per the instructions of wine. In order to make something like this available to wine you have to create a symbolic link to the serial port in your /dev directory inside of the ~/.wine/dosdevices directory. You’ll find the proper entry for the device in /dev if you have many serial devices plugged in or if you have never seen one before it may be helpful to do one directory listing with the device unplugged, and then plug it in and do it again and see what has been added to the /dev directory. The FTDI drivers create 2 separate entries. It may not matter but I linked to the one that began with tty. and that worked. Mine is named “tty.usbserial-A600ezYy” to make it available to wine you need to put a link named “com1” or something similar inside the dosdevices directory like:

ln -s /dev/tty.usbserual-A600ezYy ~/.wine/dosdevices/com1

This is now where I ran up against my first and only problem with getting this to work. Perhaps I just didn’t read the instructions for the X-CTU program properly but even after doing the link nothing showed up in the list of ports in the app. It turns out you have to enter them manually.
X-CTU Screenshot
So in typical genius, step 1 is listed after step 2 in the interface ;) In the second part of this window notice the “Add User Com Port” section. Enter the name that you used in the link command above, in my case com1 and click the add button. After doing that you can now select the port and it will work!

Can an XTension driver for distributed IO and serial via XBee radio’s be far behind?

Has anybody seen a shield/breakout board that provides opti-isolated inputs for these things? Something like that would make these even more useful to peppering around for remote control...


Arduino Chimes

Previously I had finally gotten out an arduino board that had languished unloved in a drawer for a year or more and actually sent it a flashing light program. Proving that I could actually do something with it I set out to build something more interesting. Always looking for interesting ways to alert you to various non-emergent things in XTension I wanted to have some wind chimes play me a tune. This little project gets it’s music data from the serial port. Right now just the USB plug built into the arduino, but ultimately through a ethernet shield so that I can connect to it from the DIY interface of XTension wherever I end up putting the thing.

the point of a serial protocol as opposed to just embedding it into the program is that I can send it from XTension later. The DIY interface can easily handle sending that list of bytes in response to action or information and playing me a different tune. And just learning how to use the serial interface on the thing too which is important for future projects.

I know someone is going to be concerned about my connecting up those motors directly that it will overload the output pins. I don’t think the current is enough to hurt them any but if I have problems I can always go with a transistor switch, but this was to be a simple proof of concept ;) I am also going to add a reverse diode to absorb the inductance current when they are turned off, though it hasn’t hurt anything playing with it so far.

So much for my first ever project actually programming an arduino. I think I’m going to be spending a lot more time with these things!


Arduino At Last

I have no idea why this has taken so long for me to get around to beginning to play with these. I don’t know why I decided to get out of bed and finally do something with it right now. I’ve had several old arduino boards from Sparkfun in my top desk drawer for literally years. I was probably avoiding them because I knew once I started it would only open up years of work on things that I didn't have time for and didn't really want to know what I was missing... But I've ruined it now. It's no big deal, it's no great accomplishment but the little arduino board connected to my Mac right now is flashing it's LED under my own control.

I played with trying to burn PIC type chips probably 10 years ago but I refused to run windows and at the time that made it virtually impossible to actually do that. Now days that is no longer the case. I've been ordering little boxen from sparkfun and others for a long time now and the pile of things I really need to build something out of has grown alarmingly large. Now just have to figure out the setup of these XBee doohickies and it's going to be a very interesting year.


Wiznet Configurator

Wiznet makes an excellent ethernet to serial board that is inexpensive and is fully supported by XTension unfortunately they never had a Mac version of their configuration utility that lets you give it an address and setup the serial port.

I noticed yesterday that they had published the specs for talking to the boards making it possible for me to throw a configuration utility for the Mac together. I could theoretically compile it for Linux and Windows too if anybody is interested let me know, I just dont have a machine handy for testing those targets so I haven't done so yet.

The program seems to work and implements all of the available fields though some of them appear to be different in the version of the firmware that I've got than what is documented. Indeed in the documentation even the length of the data packets is wrong so i'm not sure the things i haven't tested actually work.

To use it plugin a 5v power supply and ethernet to your wiznet board. It will assign itself an address or take one from your DHCP server depending on. To find it run the software and all wiznet boards found will be displayed. Double click one in the list to edit it.


To use one with XTension it needs a static IP address and be in Server mode. Then setup the serial port for whatever settings are needed for the particular device. This should work with CM11's and W800's and Weeder chains and just about every other device in XTension that supports a remote TCP connection instead of a local serial port.

I was unable to make the direct connection to the device work, so the configuration is returned via a UDP broadcast. What this will mean for having multiple devices on your local network I dont know yet, I only have the one but i've just ordered some more, and some with multiple ports to experiment with further.

This is released as freeware and AS IS. Let me know if it gives you any trouble and please feel free to make a small donation via paypal to james@sentman.com if it turns out to be useful to you.

(update: 2/8/11 added the linux compile. I haven't even tried to run it but it might help someone out, please let me know if anybody finds it useful)

wiznet devices can be purchased from Sparkfun as well as Saelig Electronics

(UPDATE: 2/10/2012 discovered an error in the server/client/mixed setting of the program. It swapped the mixed and server modes due to a misprint in the documentation so you might have reconnection issues if you thought you had it setup in server mode you were really in mixed mode. Setting it back up (and turning off the serial debug flag which may also have been on by mistake in that version) you’ll get it all sorted out. This blog is moving and the new entry with notes on the new version is now at: http://www.planetarygear.org/2012/02/wiznet-configuration-update.html )


Expensive printer taunts me

I hate my Epson Artisan 800 printer. I hate it, it's not got long to live until I salvage it's internal organs for motors and gears to use in other projects unrelated to printing. It was ludicrously expensive but I liked the fax and scan and the ability to print on CD's and DVD's (which I've used exactly once since purchasing the thing) The scanner has worked well and the quality is pretty good. The printer has given me a couple of good prints but mostly I dont use it for pictures which i order from online services.

The document feeder for the scanner/fax has never worked. But I'd been using it for a month before I tried to use the document feeder so I couldn't return it. It feeds one page, then tells you there is a jam. There is no jam, you can't clear it. You have to bang it up and down just shy of the amount of force necessary to break off the plastic hinges and then it will clear the jam.

Yesterday I tried to receive a fax only to be told that the light cyan ink cartridge was not responding? And needed to be replaced. well.. OK waste all the ink in there and replace it. Meanwhile the fax was, I think, received in the background. It chewed on the new light magenta cartridge for a while and then told me I had a fax to print and I told it to go ahead. At which point it told me the light blue and dark magenta carts were now not communicating and needed to be replaced. these also were not out of ink and were working fine just a couple of days prior. So I replaced them too. But now I had lost my background fax needs to be printed message. Though I did find it by going through about 7 levels of menus to re-print the last fax received. So I got it.

Now today I go to send a fax (being careful as usual not to use the document feeder) and I get this hilarious message:

My printer wants to die, and it wants me to help it to it's reward. So I'm off to surf macworld printer all-in-one reviews. Or maybe I dont need a color ink jet anymore at all... I hate printers. Why do they all so expensively suck? I'm thinking that I might spring for the HP unit with the ink that is more expensive than individual molecules of anti-matter just to have one that works. But Kodak claims their ink is the cheapest and their units get good reviews except for the scanner, which is the part I'm mostly going to be using. Then my friends are telling me that canon ones are also excellent, I love canon cameras and video devices so I'll be looking at those too.

But I can tell you, no more epson devices will ever cross the threshold of my home and this one will be leaving in very small pieces.

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Kitchen Bookshelves

It has become necessary to begin a small woodworking project for the preservation of sanity. The kitchen needs a skinny, open frame book shelf for cook books and such to get them off the counter. I have quite a bit of lumber that needs to be used up for projects so a little complexity is added by having to make use of whats already taking up space in the garage. Some good pine 6 inches and some more that is 3 inches which I'll joint together for a 9 inch shelf which is wide enough for most of the cook books. It's a little skinny for stability but I can screw it to the back of a cabinet to make sure nobody pulls it over on themselves.

biscuit jointery
Used biscuit joints to join those 2 pieces together for the full width of the shelf. If I was buying lumber of the proper width this step wouldn't be necessary.

clamping the shelves
clamps are a bit big for these little shelves but I have enough of the bigger ones to do all 6 shelves at once. After they are clamped I ran them through the thickness planer to eliminate any differences between the 2 pieces and they feel much more like a single piece of wood except for the changes of grain. But those will be less obvious after finishing. My planer is a cheap one and it leaves a bit of a dwell as it goes in and comes out of the blades, if I had remembered this I would have made each shelf an extra 4" longer so that I could trim off the section that got that flaw, but it isn't too bad really, makes it look a bit more like recycled lumber and have some extra character.

edge routing
After trimming the edges so they are the same finished size I ran them through the router table for a nice ogee edge. If I had planned ahead I might have added edge bocks to the outfeed side to avoid the little bit of tear out on that side, but only 1 actually looked bad enough to notice and I sanded them out fairly good.

jointery layouts
The uprights are 4 1x2 hardwood pieces. Not just putting them on the 4 corners but adding a bit of character. The back ones are flush with the back, but stand proud of the edge far enough to clear the beading I'm going to route down each edge of the uprights. The front ones I started an inch back but the same amount proud as the rear ones. Since we loose an inch front to back the stability of the thing is further reduced, and it's going to be tall about 14" between each shelf as I want the top shelf to be high but it's going to be screwed to the cabinet anyway.

checking the cutouts
just checking the back cutouts. That upright isn't the final one, it's actually 3" wide instead of 2 and just a short scrap piece that I used to setup the beading bit in the router table. They look pretty good I thought.

Rough assembly. I thought about doing some fancy tenon joinery inside the cutouts, but that would have been difficult and this was a quick weekend sanity project. So after lining up just placed an inset screw through to hold the shelf. After this was dry I plugged the screw holes and sanded them flush. Almost invisible and yet still very strong.

The finish is a mahogany gel stain and spar urethane varnish. I dont normally like gel stains but this gave the pine a really nice dark and even finish that would not have been possible with a regular stain. Also I left some extra stain in the beading for further antiquing. It looks really nice and is only a little darker than the stain of the cabinets it's attached to.

beading closeup

The natural uneven take up of even the gel stain made the wood look much more interesting, I like the effect on the uprights very much. I could have reduced this with a pre-coat of a 3 pound cut shellac prior to staining, this is a great technique for any non-hardwood you're finishing with any stain but it would have added an extra day to the project, and it really does look good the way it came out.

in use with stuff

screwing it to the side of that cabinet makes it rock solid. Another detail was a little 1 inch cutout at the bottom of the back upright. This lets it sit flush instead of against the quarter round molding that runs along the bottom of the cabinets. All in all I'm very happy with it, the spousal approval level is high for a short duration very inexpensive project and it looks great.


Poor Wiring

I have some lamps in my bedroom that simply will not regularly turn themselves on and off via X10. I moved plugs around yesterday and spent some time looking for something sucking signals or generating noise, but just didn't find anything like that. I am the proud owner of the monterrey instruments X10 signal analyzer so I am able to measure signal level and noise and there just wasn't any noise to speak of. THe signal level however was very interesting. In most places the outlets in a room are daisy chained one to the other around the room. The first outlet below the switch box in our bedroom had a signal level of .3 volts, which is excellent. 4 outlets around the room where the lamps are plugged in the level was down to 13 millivolts and the X10 module couldn't see it at all. I unplugged everything between the first outlet and the last and still it made no difference. It did bounce around a little though. Wiggling plugs and moving them around let me get the signal up to 20 millivolts and the module would sometimes be able to read it.

While doing this I took a good look at the outlets. They are the cheapest kind you can buy. They are all loose in the boxes. They are likely wired via the "backstabbed" connections and the screw then used to send power to the next one in the fastest and worst install method possible.

I will be replacing them soon. Backstabbed connections should never be used if you're concerned about your safety or about your X10 or other remote control signal quality. Screws can come loose too, yes, but if you torque them down properly they wont. Plus I can check them all again in 10 years and tighten them up if necessary. The backstabbed connections cannot be tightened up and just get worse and worse.

The way I'll be installing them will be via wire nuts, pigtails and the screw connections on brand new, high quality outlets. In each box, for the most part, you'll find the power inlet romex, and the romex carrying the power on to the next outlet. Those should be properly twisted and wirenutted with a short pigtail of wire. The pigtail goes to the screw terminal on the outlet. Doing your own outlet replacement isn't hard, it isn't complicated. Go get the little book the hardware store has on how to do it properly and safely. And obviously, if you're considering that you might be able to do it with the power on, or if you think you dont need to check each outlet with a voltage sensor because often one outlet in a room is on a separate circuit then you shouldn't be dreaming of doing this yourself. Most electricians will be happy to wire your house to your specifications. They will just charge you more hours of work if you make them use the good methods which take a few extra minutes per outlet.


Multimeter Support for XTension

When I learned that there were multimeters out there that had documented serial protocols I added that to my todo list for XTension support. I bought this one from radio shack more than a year ago and never got around to looking at it in any detail. Now with the kids just starting back at school and having just unearthed the protocol docs it was time to do something about it while I refreshed my memory on the code I haven't touched in months while I played with the kids over the summer. This is just first light, it's not quite beta ready yet but it's talking to XTension and updating a unit value in the database for the displayed value. Here is my Radio Shack model 22-812 multimeter with an FTDI usb/serial adaptor sticking out of the top and a View in XTension showing the value.

meter is online
Still on my to do list is a significant change value that can be set, otherwise you will get a lot of updates at higher resolutions. This is just measuring line voltage here and it's bouncing around a couple of tenths of a volt constantly. So being able to set that will help. Additionally I could do some conversion to handle the auto-ranging... Or just recommend that if you're likely to change ranges while you are reading something to turn off auto ranging. The way the protocol works it just sends the display characters, not an ultimate voltage or reading. So this display might be volts or millivolts or ohms or megaohms or milliohms... This can read out anything that the meter can read so you might use it for temperature or with a clamp on current transformer or something. One thing I have noticed is that the auto-off feature to save the battery seems to be turned off when logging to the serial port. This is good because it means you could power it with a 9v wall wort replacement and it will keep running and not shut itself down.

We shall see how useful it turns out to be for me. In the meantime if you want to play with it before I get around to an official beta please drop me an email and I can send you the new builds that include support for it.


Under cabinet LED lights

Really nice new house, but the lights under the cabinets are so ancient that the tubes actually have a starter and click click light BZzzzzzz. Totally unacceptable! Good under cabinet fixtures, even of the regular florescent type (and I have no interest in the halogen type, too hot and wasteful not to mention continual bulb changes) are very expensive, upwards of $50 a light and more for the wider ones. Little LED ones are available but they are even more expensive but not nearly as bright. Current limited power supplies for LED's are available now directly from china at pretty decent prices and one watt warm white LED's are not that expensive anymore either so I tried to roll my own to replace the lights here.

The power supply is a 7 to 12 LED driver from dealextreme.com and the LED's are from them too. All you have to do is solder them in series and glue them to a heat sink. But that is not as easy as it sounds...

I decided to reuse the fixture cases already wired in under my sink, the power supply is small and will easily fit in them. I used a piece of u-channel aluminum an inch or so shorter than the length of the bulb that used to be in the fixture and arranged the LED's upon it.

First lesson learned: The wire I used was too thick. It's just a watt of power so thinner wire would have been fine and would have made it much easier to manage during the glue up portion.

Here's the channel with the led's being held down while the epoxy cures with blue tape.
blue tapeas it turns out, blue tape could not hold them in place with the resistance from the overly heavy wire I used and none of them glued flat. Heat kills LED, they must have good attachments to the bar or they will die and dim early.

So I pried them all off and began again, this time using one of these blue clamps which have cutouts in the face just about the right size to cradle the lens on the LED without breaking it. So now they are glued on right and they are really quite impressively bright even without any lenses.

I just screwed them into the same case as the old lamp, replacing the ballast with the new power supply. They are quite a bit brighter than the old lamps and are a superior color temperature the heat sink gets warm to the touch but never so hot that you couldn't hold it which means that either I"m not making good thermal contact with the LED's and they will shortly self destruct, or that it's working great and well within thermal limits for long life.

Putting the diffusor back over them though reduces the output considerably, so for now I've left it off. You can't see them under the cabinet anyway, but I need to figure out some better ways to make it pretty before I replace the rest of them.


feels so good when the pain stops...

I haven't blogged any more projects since moving as moving and summer with the children home is enough of a monumental task without having to document it for posterity. I did however just solve an ongoing problem with the automation in the new house and it is such a relief that I have to tell somebody about it.

Basic functionality is to manage the outdoor lighting, can be as simple as on and dusk off at dawn or dimmed and brightened in response to movement in the yard or anticipated visitors or whatever. I never quite got to that point. I installed a used UPB switch that I had purchased in a large lot off ebay a year or so ago and used that to control the lights over the garage doors. Sadly I added 2 variables at the same time by doing that and also putting in some fancy cold cathode compact florescent bulbs at the same time. Something there generated huge amounts of powerline noise when they were on. They would turn on just fine, but after a few seconds they would no longer turn off. They taunted me for a month of my waking up only to discover the lights still on. Sometimes other X10 switches would turn on during the night too, mostly just the backyard light on the same circuit so no big deal but also very frustrating.

After weathering this for a while I installed an inline X10 filter between the switch and the lights thinking this would surely fix the issue. I just had done the same thing to the overhead garage lights after I discovered that GE replacement electronic T8 tube ballasts also made enough powerline noise to shut down automation in the whole house. (doesn't some government agency test these things to see if they are any good before letting them put all those stickers on things?) Installing the filter was no easy task either. I actually added another 2 gang box above the switchbox in the garage wall and mounted it there relocating wires. There was no access to the light boxes themselves at all.

After all that the problems remained. Deciding that these mail order CCFL lamps were just too powerfully evil to be saved I broke down and bought replacements of regular CFL bulbs from the hardware store and installed them. The outside lamps make this very difficult as they are very fancy fixtures with totally rusted bolts that do not come apart easily. I still have scrapes and scratches on my hand from squeezing it into them holding the bulbs as far as they would open.

After all that, STILL no change in the amount of noise!

That left only 1 other possibility, well, it might be that the brand of bulbs I bought at HD was defective too but I've used those before without difficulty. I took out the inline filter and spliced an extension cord into the line going up to the lamps and plugged it in. The lights turned on with no noise. I turned on the switch with no load connected to it at all (but with the lines carefully capped for safety of course) and it generated all the noise all by itself! The lights were not implicated at all it was a defective switch!

Replaced it with another switch and there is sanity again with my outdoor lighting. I had been avoiding really going to town installing switches in the house until I was certain things would actually work. Now I think I know why this person was selling a whole house full of UPB switches on ebay. He was tearing them out after tearing his hair out why they just wouldn't work.

So never overlook the obvious, that is the most likely place for the problem to be. Now to move on to other sources of frustration!


X10 Controlled Nightlights

First project in the new house worth documenting is the install of some X10 controlled LED nightlights. These got a high level of spousal approval ;)


A reason to buy an iPad?

So I Oooo'ed and Ahhhh'ed along with everybody while reading about Apple's new iPad. But apart from a desire to develop remote control apps for XTension on it I really couldn't see how I might actually use one. When I lug my laptop off with me it's so I can do development and I need REALbasic and XCode and all the ancillary things that go along with them. Those things, while they compile for the iPad (well not RB yet but one can hope) they don't actually run on it... So it would be nothing but a plaything for me if I were to buy one. My plaything budget, while it has increased over the years, has not grown to the point where I can pick up $500 toys without some planning.

So I put the idea out of my head.

Then last night as I was reading teh intertubes in bed, I began to think wistfully about our next family vacation and remembering past family vacations and I have brought my laptop along on all of them. I like to be able to log into the house remotely and make sure the cat lady has come when she said and that sort of thing and add a little extra randomness to the vacation light programs. But I also then tend to do actual work. I like my work so this isn't really a problem for me. If I only brought an iPad along I'd still be able to do all those important things like logging into the house and getting my email and VNC and all the rest, but I would be prevented from actually doing any real work. Since the compilers wouldn't be sitting there taunting me to come and accomplish something I would be able to eschew work with a clear conscience.

I'd have access, I'd have books and the web, I'd just not have to do any work. An enforced vacation without having to leave all my connectivity behind. Now that might just be worth the entry price someday.

Course.. the problem is that I can pretty much do all that with my iPhone now...

1 comment

22.5 degrees

Or how I learned to stop worrying and embrace the protractor...

Did I mention cutting crown molding was a black art? Those corner units need a 22.5 degree angle cut, and my miter saw has an indent at that angle, but of course it's a little bit off, just like the 45 degree indents and so you have to measure each time you switch it from one side to the other... But eventually it's all up and done and really looks nice. It's just primed right now but the whole thing is getting a fresh coat of paint and all cleaned up and one more step complete.