Archives for the month of: March, 2011

Oh yes, I think this will do very nicely:

Mmm, shiny.

I decided to create an on air light to indicate when we’re broadcasting. While I could have just wired a switch to a light fixture, I wanted to take the idea a step further. Using Ustream’s API, I set up our on air light to turn on automatically when we start broadcasting. This project was just for fun, but learning how to use the XBee Internet Gateway to get the Arduino online wirelessly will come in very handy for future projects.

[from Make:Online]

As some readers may know, I have an alter ego producing and hosting a wine industry talk show that airs on terrestrial radio as well as podcast to the Internet. As part of the evolution we have something of a ghetto setup to allow the curious to watch as we tape our episodes (tape on Wednesday, air on Friday). Since we do use the USTREAM thing, having a beacon like this to let us know that the stream is live (and that we should behave ourselves) would be mighty handy.

So I’m putting this one on the list of show projects, to make our production that much better. I do actually have some other show projects, including:

I’m sure that list is really just getting started.


Funny, the things you get tied into when you join an online community such as RepRap-Dev, the developers mailing list for the 3D printer I hope to eventually build for myself.

It seems that we now have a few contenders throwing their hats in the ring for a chance to be the electronics-of-choice for RepRap.

Meet Sanguinololu (or visit its RepRap wiki page). Difficult to pronounce, being a mashup of Sanguine (the word), Arduino (the prototyping platform), and Pololu (who sells motion control units for driving stepper motors that enable 3D printers to actually work); if they can hold to the mission of being less than USD100 to build, that’s really good news to cheapskates like myself.

But hold on, there’s also the Generation 7 electronics, which also promises to compete on the price performance curve.

And then there’s RAMPS (RepRap Arduino Mega Pololu Shield), which has quite a lot of momentum, but is spendy but proven to work.

My biggest issue with all of these three options is their dependence on Pololu driver boards, which are (wait for it) out of stock.

How NOT to enable a growing open source hardware movement.

How NOT to enable a growing open source hardware movement.

You just knew that was coming, didn’t you? It doesn’t matter how affordable the Pololu drivers are if you can’t actually buy them.

[If there is a unifying theme to what I’ve seen so far in the Arduino/RepRap world, it’s this: it’s a supply chain, people. If you choke off or constrict any part of it, the whole thing suffers. Newbies like me are left wondering why we have to venture onto EBay to bid or buy Arduino Mega knockoffs from Hong Kong or Shenzhen when we’d rather be supporting the people who are actually developing them? The same generally goes for RepRap electronics, Pololu drivers. Does nobody have an interest in this movement growing?]

And finally, there is a fourth contender in the ring! It’s getting positively crowded in here! Along comes Repic, which claims to come in under USD90, but requires RepRap folks to venture into the land of Microchip PIC microcontrollers in order to go there. I sense a black sheep, but I’ll keep an open mind.

I can at least agree with list member Neil Underwood, who put it nicely:

3 open source electronics all competeing head to head to lower the price point/increase the capacity for RepRap electronics can’t be a bad thing.


I can’t help but see this as a good thing

Yup, legitimate and honest competition, even in Open Source Hardware, is a good thing.


Being that it’s Friday evening here, I think a bit about the weekend to come.

The weather this weekend is a mixed bag, but I’m going to need to hang a door on the chicken run, and start working on the inside of the chicken coop, so that we can put those ladies to work! Now then…

Today I was starting to look over application notes and data sheets for a home power meter that I can use to measure power that we’re buying from PG&E and measure the power we’re not buying, but rather selling to PG&E. Being the early adopters that we are, we defied the tin-foil hat wearing residents of Sebastopol and went ahead with getting our Smart Meter installed.

It’s pretty. It’s digital. It’s the future, people. I don’t understand how you can deny that there’s already freakish amounts of RF coursing through your body every minute of the day as you shout into your Bluetooth headset jammed into your ear canal, which is linked to your wireless phone tucked in your pocket (mere millimeters from your flesh, mind you), sitting in front of your computer, and you’re upset about a meter on the side of your house causing you harm? Seriously?

Anyhow, we now have a smart meter that runs both ways. Unfortunately, and partly due to the fact that our neighbors all cower in fear of progress, we can’t actually go to PG&E’s website to see how much power we’re using on a real-time basis. Thanks, neighbors!

[And don’t get me started on the solar array we had installed using Enphase Energy microinverters. They have a subscription-based web site called Enlighten that will show you — Ruby on Rails style — how much energy you’re generating. But they lock up the transceiver (that you bought) nice and tight, and expect only that you will obediently plug it into your home broadband network so it will transmit your power generation data to them, so they can turn around and sell you your data back to you. Ridiculous.]

So, I’m left with the option of measuring and logging it myself. There are some very well worn Arduino forum posts and even some cool European-oriented open source hardware websites where folks have set this up (that’s not exactly being fair. There is a growing community of people on that site, it’s just that it takes a very 230VAC non-split single phase view of the world). And now there’s even someone in the U.S. who has helped figure out the nuances of split-phase current transformers for us lay people.

So if I was fully equipped, here is my power meter wish list:

  • Accurate to +/- 1% from 1A to 200A (which is the size of my residential service)
  • Powered by it’s own 240VAC circuit, to ensure voltage reference for each half of the single phase.
  • Wifi or XBee or some other RF transmission for the short distance of getting the signal into my house. Don’t forget the tin-foil hat.
  • Actual measurements will be taken by a circuit I’ll design that uses two separate Analog Devices ADE7753 tied over SPI to an Arduino-compatible MCU.
    • I will likely use two split core current transformers (200A) that meet my desired accuracy for the mains.
    • I will need to find two smaller current transformers (20A) that will work for the solar microinverter lines.
      • My biggest problem here is finding CT’s that will perform well enough under low-load conditions (< 1 amp) as well as full load conditions. And as long as I’m not spending a fortune to do it.
    • One of the ADE7753’s will measure the incoming service from the utility.
    • The other ADE7753 will measure the “incoming service” from the solar array microinverters.
    • Together, I should be able to work out my net metering myself.
  • The MCU will retrieve measurements from the ADE7753 and store it until it periodically forwards a collection of the data to a waiting RF receiver, hooked up to a real computer (well, okay, a Mac Mini, but it’s cute anyway) that will properly compile it into a database of sorts. Alternately, it will upload the data using a RESTful web service to a cloud-based web app that I write myself. Yeah, okay, keep it simple.
  • From there the data is stored on servers that I control (assuming I don’t go with Google AE, that is), and the data is mine to use as I wish. Enphase be damned for their closed-source, closed-minded approach.

Simple, right? We shall see about that. I’m figuring it’s my 2011 on-the-side project for getting on top of our energy usage.

My biggest problem right now is that I don’t have any of this equipment (except perhaps the Arduino). Sigh.

Yesterday, I picked up a band saw for $20. (thanks, Craigslist!) It’s in need of some repair. Let’s see what’s funky about it.

Craftsman 10" benchtop band saw

Here is the little bugger now. From the front, it looks to be in relatively good shape. Notice the “throat” area of that saw (the  area between the blade and the left side of the saw from this photo’s perspective). The fact that it’s so deep (heh) means that it has clearance on par with band saws much, much larger. The table is anodized aluminum from the looks of it, and is slightly corroded.

Yes, that’s the back of my car. Good thing you can’t see the floors.

Bandsaw power switch is missing the safety key that allows you to turn it on.

Here’s the first real problem, easily solved. The safety key for the power switch is missing. The guy I bought it from had one that fit his Sears table saw, and so he didn’t need to get a replacement. I am not so lucky. Still, it’s only $6 at Sears to replace, so then I’m out only $26 for a very capable band saw.

The bandsaw is opened, and the drive pulley is damaged. It will spin freely without moving the timing belt, which would in turn move the band saw blade idling pulley.

Now this is the real problem. No, not the sawdust, the drive pulley. You can barely see it from the photo (it’s the black plastic thing just left of center on the photo), but it’s backed off about 1/2″ from the motor spindle, and it appears to be stripped of its timing belt teeth on the pulley itself. This means that when you turn it on, the spindle will rotate furiously, but the timing belt and the idling pulley on the other end of that belt don’t move, which means the saw blade doesn’t move.

Sears sells a replacement for $13.50 online. So  now the bandsaw will cost me at least $39.50, but that’s still a bargain.

The front panel shows that the drive pulley has been rubbing against the front panel, wearing off the paint and likely helping cause the demise of said pulley.

If you look at the inside of the front panel, you can see where the drive pulley has been rubbing up against the panel, wearing a nice donut shape through the paint to the bare metal. Good times.

The back side of the saw.

Finally, the back side of the saw, which shows some rust pitting on several parts. Again, mostly cosmetic, but should be addressed with a nice cleaning. Basically,  some hardware replacement will  be needed if the rust can’t be cleaned off. Also, I would imagine that replacing the capacitor on the motor would be a useful thing to do. Then a coat of rust-resistant paint over the pieces and this should be a serviceable saw.

I’ll write more as the cleanup of this particular tool progresses, and hopefully it will actually work here pretty soon.

Update 4:50pm, March 3: Having ordered the parts on, I didn’t take into account sales  tax and shipping, so the total for the key and the pulley is $30 delivered. I should get those parts next Tuesday. So I have between now and then to clean this little beasty up.


Why on Earth would someone want to make everything themselves? I mean, isn’t it cheaper to just hustle down to the Target/Best Buy/Wal-Mart/Costco and buy it cheap?

Well, I suppose in one sense, it is cheaper, in that it might take less money to accomplish that, at least for now.

[Engage Tin-Foil Hats]

But in a world where oil prices are increasing, transportation costs will start to climb, meaning those cheap products will stop being cheap. I’ll leave the doomsday conclusion to that thought for another day. Suffice it to say, however, that possessing the tools and skills to build things yourself is going to really help in the decades to come, perhaps more than at any time since the end of World War II.

[Okay, Tin-Foil Hats Off]

This little corner of the world is going to chronicle all of my side projects. Builds regarding items that actually can be used to build things. Builds of general interest. Builds that interest nobody but me. I know that makes it a mixed bag, but it’s my party, and I’m going to make the rules.

So, why is this sexy? I don’t know, just ask my wife. It gets her ridiculously turned on that I make stuff. Okay, that’s an exaggeration. Actually, it has more to do with the fact that I’m working on her projects, and she generally expresses her appreciation in an PG-related manner.

What projects am I looking to profile on this blog? Well, here’s an incomplete list, in no particular order:

So, watch this space for further developments.