How to ‘piggyback’ driver chips on Ladyada’s arduino motor shield

I really like the motor shield from adafruit industries. It is simple and it allows me to plug it in and start playing quickly. I usually have giant machines in my head, and the shield just wasn’t designed for those kind of motors.
You aren’t going to end up running your prius off of one of these controllers, but it turns out that you can almost double the max motor current draw just by soldering on some chips.
From Adafruit’s forums I figured out what ic’s I need to order (L293). Here is the label on the esd bag.

Now all that you need to do is solder them on top of the existing motor driver chips! As strange as it sounds, the theory has been vetted. Each one of those drivers can handle 600mA continuous. By stacking one on top of another they each handle ~600mA and you end up with ~1200mA! The motor shield has two driver ICs mounted on it, they are the two outer ones.

Here is a shot of the board. It is assembled, but it only has one motor driver chip per channel (‘channel’ feels weird there, but you know what I mean)

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An easy fix for atm card skimmers…


The other day I was using an ATM with a color touchscreen and I was thinking how if it had a skimmer attached I wouldn’t have a clue. They all look different, with different forms, materials and behavior.


Then it came to me: Why not have an option on the atm where it will show you a photo of itself on the screen? It seems like a great solution to a ridiculous problem. Other than ATMs that don’t have color screens are there any issues?

Sparkfun Autonomous Vehicle Challenge

I just got back from the Sparkfun AVC. It was a blast! I shot a lot of video, but that will take a while to get processed edited and uploaded. In the meantime here are the things I thought were cool on the ‘factory tour’ with a few AVC shots thrown in.

This pond instill fear in a lot of AVC owner/operators. Strangely enough the airborne division didn’t seem to mind the water as much as the trees.

This lil guy broke down the day before the big race. Sigh. It’s not easy being autonomous.

Known for it’s blazing speed, Bluebot held it’s own. It eventually claimed first place in the DNF division!

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Missed out on Sparkfun free day? Buy it anyways!



So, like many of my readers I spent the morning watching firefox time out on sparkfun’s website. Eventually the clouds parted just in time for me to see the ticker go from 70k to 98k, to 100k. Just like that the first ever (annual?) sparkfun free day was over. I was bummed. Then I started thinking about it. Everything in my cart was something I wanted, and I did have a good time this morning, and I had a good time thinking about what I was going to get, and why. I have always thought sparkfun is a really cool company, and the fact that I can’t get this stuff for free isn’t going to stop me from buying it.


Right now there are probably a few thousand people still crashing the gates of sparkfun.com trying to get in on free day. It is over. They rewarded us with the chance to get free stuff. I personally am going to thank them by buying it anyways.


Thanks Nate, thanks Sparkfun!

Weird banding on Canon 7d explained!

The other night I was out filming traffic. I ended up getting a really weird camera artifact. It looks like a dark bar that rolls through the shot from bottom to top. At first it made me freak out a bit, thinking that the camera was somehow broken. I eventually figured out that it is the result of A) a flickering light source and B) the right (wrong) shutter speed. I think the streetlights were tungsten bulbs, but they may have been HID bulbs. Whatever they were they definitely had a flicker to them.

I read somewhere that ideally you should shoot a shutter speed that is double the frame rate. This gives you a 180 degree shutter and it should look very similar to film. The way that I made these bars appear was by changing the shutter speed away from 1/125 when I was shooting 720p60. I have ideas as to why this creates the banding, but they are all theories. If you have any more insight pleas tell me in the comments!
Moral of the story: keep the shutter speed at twice the frames per second. Change the aperture, or buy a faster lens!

good gear to go with your shiny new canon 7d


I can only hope that there will be a lot of other happy people unwrapping new cameras this christmas. I bought my 7d about a month ago, and the best/worst thing is that now I realize buying it is just the beginning. I want to buy sooo much gear to use with it, and it is tough to find well recommended, modestly priced gear. Here is the short list of what I have or want to buy, to wet your creative whistle.


bogen tripod with fluid head.
If you buy nothing else on this list, get a tripod and a fluid head. The 5d/7d do not have ANY image stabilization capabilities, so if you plan on using any lens longer than a 50 you will need to use a tripod. The fluid head is also critical because many other types of heads are built for still photos. They are easily adjustable, but not in smooth movements. A fluid head is designed for video, and is the only real way to get a smooth pan.

Hit the MORE for more!
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Slow motion from the 7d. 720p60 to 24p How-to

There were a few different stages of excitement that I went through after getting my Canon 7d. First I played around with all of my manual nikon lenses (using an adapter of course). Next I marveled at the settings and the live view feature. Finally I decided I wanted to go out and shoot some slow motion video. This is fairly easy to do seeing as the camera shoots both 720p and ntsc at 60 frames a second. The software side of slowing things down required some thinking, but it’s easy once you get the hang of it.

Here is what I (and the wisdom of the internet) have come up with.

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Site hacked – media temple’s reaction.

UPDATE – I just spoke with the VP of customer service at media temple. It seems as though there is a lot in the works. He wanted to reassure me that their reaction to this has been very carefully thought out, and that they are currently investigating the hacks.


While I generally want to know everything about anything immediately as it happens, I understand that if MT handled this that way it could lead to a situation where an exploit was widely disseminated before the vendors had a chance to patch it. There are an incredible number of pieces of hardware and software involved, and it only takes one exploitable piece to create a problem.


In short, sit tight. Media Temple will hopefully release more info when the time is right. In the meantime you can rest assured that their measured reaction is the result of careful consideration, not sloth.

I will leave the original post below quoted for reference.

There aren’t many answers here, but recently this site was hacked (which is bad) and my host Media temple saw errant behavior, (and recognized it) changed the ftp password, and restored backup to the site (which was good!)


At first I was not very upset. These things happen, and it seemed like media temple did the right thing in a timely manner. Then today I searched for one of the php files the hackers had put up on my site and discovered this page (google cache) which has quite a few other sites that had been hacked in a similar fashion. Something very fishy seems to be going on here.


Media temple sent out an email blaming the hacks on old ftp passwords. That would make sense if it was a handful, but hundreds of sites? That sounds like something only Media temple could screw up.


I sent in a ticket asking them if they had been compromised. I’ll update it when I have an update. Personally I am much more upset about media temple’s failed coverup than I am about media temple getting hacked.


Here are a few links from other people who seem to have caught the story earlier then I. One guy had his blog hacked twice!


http://www.inquisitr.com/47860/the-epic-wordpress-mediatemple-failure/

http://www.kyle-brady.com/2009/11/07/wordpress-mediatemple-and-an-injection-attack/