There’s a bunch of builders blogs out there these days, and if you’re like me it’s hard to keep track of them all. Luckily we have RSS, but even then it’s hard to track down and enter all those addresses.
To help fix the problem I’ve created a consolidated RSS feed containing around 40+ of the builders blogs I track that are focused on droid building. i.e. they post about building progress, techniques, R2 events etc. (rather than lots of Off-Topic posts with a bit of building thrown in.)
The new feed can be found here if you’d like to use it too, or drop me a message if you’d like your blog added
If you are included I’d appreciate a link back to my website or maybe a link to the Mega feed.
I also highly recommend Google Reader for all your RSS reading needs.
I can’t believe it’s been a month since WonderCon — I’ve done very little on Artoo since, which as been a nice break, but I feel guilty that I still need to go back and post on work I’d done last month.
The good news is, as a result of us being at WonderCon there’s at least one new builder who’s jumped head first into building. What’s even better he only lives a few miles away from me – Welcome to the club Steve!
Today I did get together with Gerard to talk droid and strip my Artoo back down ready to implement my revised battery system. I was hoping to get a few more local builders over, but being easter it was hard to arrange at such short notice.
The easter bunny also brought me newer bigger batteries. I’m going to replace the smaller 7Ah batteries with a single 12V 18Ah battery. Thanks Gerard!
Now to try and get the battery to fit and still be easily removed.
I’m probably going to position the new battery just off-center with a second smaller standby battery for the RoboteQ to the right. Based on the height of the battery and the clearance needed to get it in and out, the new holder/harness will probably much shorter than my original.
I’m also even more convinced that I should loose the fuse block, which works well and even has a battery voltage read-out, but it’s somewhat overkill and gets in the way of battery removal. I could try putting it deeper into the droid, but that then defeats the purpose of keeping for the voltage display.
In closing here’s shot of my frame minus the skins
Update 4/21/08: Click here for the latest wiring schematic.
Here’s another revised version of my 12V battery and charging system. I’m now using additional relays to isolate two sets of batteries which can be charged independently.
I’ve also added a little bit more detail to the schematic to show additional connected sub-systems.
There’s also a PDF version available for you to download and print.
Here’s a couple of shots of my “finished” charging port and bracket and the associated wiring and electronics before I mounted it. I say “finished”, because I’m currently redesigning the circuit again to accommodate for charging two sets of batteries to work around the RoboteQ problem I experienced at WonderCon.
I ended up soldering the LED array to a small board. They were okay as standalone strings, but mounting them permanently to the bracket was easier this way. The ribbon cable on the left runs to the PICAXE board, and I braced it to make sure the wires wouldn’t pull out
Here it is installed in back of the port bracket
I added a length of acrylic to the original aluminum bracket to mount the additional electronics on it
Here’s the PICAXE board mounted. It drives the LED array
Almost done. I wired in the relay and switch that runs to the main fuse block and batteries.
The relay is hard to see, but click on the image to see the large image and the relay is on the top right of the photo
Here’s something small I added right before WonderCon. It’s nothing fancy, but comes in handy when trying to work inside Artoo in the field.
It’s just a row of 3 square LEDs with a small momentary on/off switch.
It’s just duct taped to the underside of the middle shelf for easy removal and runs off of Artoo’s 12VDC supply.
If you’re going to put any sort of electronics in your droid and new to it, then it’s hard to know where to start. Often you’ll be assembling from a kit.
This is a great primer on circuit building, it cover the basics from recommended tools, how to correctly solder and what order you should do things in.
Instructable.com has a lot of great articles that most droid builders could use.
WonderCon was last weekend, and it was my first real test of Artoo since the rebuild. I’d mentioned that both Gerard and I had problems with our batteries. We’d figured it much be the carpet, but I hadn’t had the problem at Celebration 4 – and in the back of my mine I had a niggling theory what was causing it.
For Celebration 4 I’d used 3 7Ah 12V batteries, two dedicated to powering the NPC-2212 drive motors, and one for the body electronics like the sound system, dome drive and speed controllers. But during the rebuild before WonderCon I’d decided to consolidate all 3 batteries into one block to make charging easier. I’d had issues with power before, but thought the problem was resolved and I could consolidate my battery sub-system. Runtime at WonderCon was approx. 60 minutes vs 180+ minutes at C4 – which is a huge difference.
Unfortunately, while I was redesigning my electronics and adding the charging system, I’d forgotten that the RoboteQ speed controller really likes a solid 12V supply, so last weekend as my batteries ran down and when the NPC motors first start-up they were eventually pulling the supply well below the minimum 10.5V required by the controller. It’s “intelligent” and shuts down if it thinks it doesn’t have enough power to control the MOSFET drivers. It’s only for an instant, and starts back up almost immediately as power is cut to the motors – which resulted in the very slow and slightly jerky movement.
So today to prove my theory, I reinstalled the the “dead” batteries from last week without recharging them, and added a separate 12V battery to the Power Control lines on the RoboteQ – Bingo! Worked first time. The issue was totally gone.
I’m kinda embarrassed that I went through this, because I should have remember that there’s a know “design feature” with low batteries and high current draw on this type of speed controller.
I’m now confident that I can pretty much run Artoo for multiple hours on a single charge – but I will have to reconfigure my electronics system again – making it harder to charge batteries in place.
I really like this photo I found of Gerard and I at WonderCon
WC2008-088, originally uploaded by Barry Brown.