Charging Jack LEDs

I’ve been busy most evenings this month getting ready for WonderCon, but thought I’d stop and post this new addition which I’ve been working on and off for a while now.

I’ve expanded my battery charging port to include some LEDs. The flashing pattern is based on the scene in ESB where Luke and Artoo meet Yoda for the first time.

The whole thing is driven by a 18X Picaxe board with some custom code. I’d originally planned on using some simple timer IC’s, but thought this would be a good project to experiment with Picaxe.

I’ve tried to capture the LED sequence the best I could, but it’s only shown straight on for 10 seconds, and even then it’s obscured by the door some of the time.

To get to this point I had to create a new acrylic mounting plate. I still need to wire in the new charging circuit Bob helped me redesign, but this was the first step in the process.

I went through several iterations and prototypes to get it to fit and work around the Robart hinges. Hence the slots on the left hand side.

I’m hoping to fix it to the 12V charging socket and use it to mount to the metal bracket I made a few weeks ago as part of the original charging circuit.

It’s also been a steep learning curve the as I’ve not really done any major thinking about complicated electronics in a very long time.

I’ll try and post more details in a few weeks, but here’s the completed circuit after a few late nights. I may switch to a smaller Picaxe, like the 08M, as the 18X is a little bit of an overkill for this project. But the price is negotiable in the grand scheme of building a droid. I’d have to guess the whole circuit costs less $35, but in the process I had to buy a bunch of stuff to figure out how to get it to work.

Here’s a a close up of the LED matrix connected to the PICAXE board.

I also had to create a voltage regulator circuit to power everything directly from the batteries as the main power distribution board will be isolated/turned off when the batteries are charging – and the whole point is for R2 to show some bling while he’s charging right?

I ended up using a LM7805 which will step down the 12V supply to the require 5V.

When I get a chance, the plan is to eventually make the LED’s display the current battery voltage when I press a button as the Picaxe 18X has a built in voltage reader.

Posted by Chris on February 13th, 2008 in Electronics | 9 Comments

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9 Responses

  1. Thomas Nixon remarks on

    Wow Chris, very impressive…you’re starting to make me jealous 😉

  2. Calvin Thomas remarks on

    That is VERY AWESOME!!!
    I like the LEDS seq.
    I’m probly not going to be able to do this on my R2, I messed up and bonded this door shut when I was getting the skins ready.
    Man, I really like that!!
    I’ve watched the video about 10 times.

  3. Bob Ross remarks on

    Hi Chris,

    That is a neat feature – very eye catching !!
    Definitely worth the extra time adding it.


  4. Thomas Nixon remarks on

    Hi again Chris,

    Do you have any diagrams as to the wiring setup for both this and the charger? I was also thinking about have as much as possible built inside both my artoos.


  5. Chris remarks on

    It’ll be a couple of weeks before I post a revised diagram, but here’s the charging circuit which has everything but the flashing LEDs.

    and my original concept with how I made the supporting bracket etc the original flawed/over-engineer circuit

    All I’m doing is chaining 5 LEDs of each output of the Picaxe, and I added a little voltage regulator circuit to drop the battery down to 5V to drive the board.

    You may want to read Murrey’s Picaxe manual if you haven’t done so already. Great stuff in there and the Picaxe is very easy to program.

  6. Thomas Nixon remarks on

    Thanks Chris… the led setup seems pretty straight forward and I didnt know about that manual…so thanksx2

    by the way I just changed my blog address its now moved to wordpress. They had better options and functionality so I thought I’d change it now before I got too deep in blogger.


  7. Chris remarks on

    Hi Thomas

    Links updated.

    This site also runs on WordPress software 🙂


  8. Tammy remarks on

    AND, the best part is, he got a legitimate steal on the LEDs. They should have been 0.49 for one LED, but he paid 0.49 for a pack of 10 due to them being marked up wrong. And of course I found them 🙂

    So they may be the cheapest thing on the droid!

    Tammy (the wife)

  9. Thomas Nixon remarks on

    Hahaha… well done Tammy!


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