Friday, September 21, 2012


Here's an illustration of the various sizes of SMD LEDs.  They're pretty cheap on ebay.  0603 Soldering tutorial.  Several more on youtube.  I'm trying to figure out what size is best for the Ladybird.

Note: on the back side there's an arrow. The arrow points to the negative wire.


  • 0603. Footprint: 1.60 x 0.80 x 0.40mm.
  • 0805. Footprint: 2.00 x 1.25 x 0.80mm.
  • 1206. Footprint: 3.20 x 1.60 x 1.10mm.

This is the 1206 data from the ebay vendor:

Electronics You Need To Get Started

Here's pretty much the electronics you'll need to put together your first plane (not counting transmitter/receiver).

Clockwise from upper left:  LiPo battery charger, brushless motor, servos, electronic speed controller (ESC), battery voltage checker, LiPo battery.  In the center are bullet connectors (note the bare wires on the motor) and props.

Here's some notes on how much these things cost, cribbed from an email I sent to MarkV over at the Brain Wagon:


here's the build list, which I tried to make as complete as possible.  let me know if I left anything off!

everything's from except for carbon fiber, epp foam, and glue which are from  all the numbers are what I paid including shipping.  all the zero items are things i've got excess sitting around from buying bulk quantities.

traditional glue is hot glue, but i like the foamtac coz it's a bit lighter and (imho) more resiliant.  try gluing a couple of pieces of scrap foam together and if it doesn't give you zen tranquility then use hot glue, keeping it as light as possible.

the epp was more expensive than i remembered... it was about $60 for 6 sheets, not 10 as was my recollection.  I'll stop everything off in the morning and we can check out the tx/rx if you've got batteries...

power system

$10.24    1500 kvm, 24 gram "blue wonder" motor
 $1.25    8x4 props (2)
 $8.58    18A ESC
 $0.00    theraband prop saver bands
 $0.19    JST pigtail, ESC side
 $0.72    2mm bullet plugs, male (3) (motor side)
 $0.72    2mm bullet plugs, female (3) (ESC side)
 $0.00    2.5mm heat shrink tubing


 $4.00    carbon fiber 3mm
$11.60    9mm 1.9# EPP foam, big sheet
 $0.00    blue velcro

control surface

$0.00    skewers (2)
$1.03    1.5mm pushrod snap connectors (2)
$6.46    9g servos (2)
$0.00    paper clips (2)
$0.29    control horns (2)


$5.50    beacon foamtac glue
$1.19    transmitter strap


$13.73    2S/3S balance charger
$14.40    3S 500 mAh LiPo batteries (2)


    hot glue gun w/ low temp setting (good one here)
    razor blade cutter with lots of sharp blades
    reaming tool or drill if you're careful (for enlarging servo holes)
    jewelry pliers (for pushrod)
    soldering stuff

Saturday, September 15, 2012

Easy Star Stabilizer Repair

 You can read the details (and see the video!) over at the Brainwagon, but the tl;dr is that the EZ* lost half the horizontal stabilizer in a crash.  I could tell MarkV felt pretty bad about it, but I told him it would be no problem to get things good as new.
I double-checked on the EZ* RCG thread, and Elapor (the proprietary foam mix that Multiplex uses is CA-safe, and CA is the recommended repair glue.

So, I used a couple of drops of cheapie Harbor Freight CA (10 tubes, $1.80 on sale) and a spritz of HobbyKing kicker and put the stab back to normal.  Total repair time: about 2.5 minutes, including taking the pics.  Don't tell MarkV, I don't even think he noticed a previous repair from where I busted off the vertical stab!

Tuesday, September 11, 2012

Quadrature Encoding Function

Oddbot has the perfect example here.  He ORs the A and B inputs so that one line can control the interrupt.  And more here.

Monday, September 10, 2012

Telemetry Cable for the 3DRobotics Radio

Here's how to make a telemetry cable for the 3DR Radio.  It's slightly different than the one 3DR sells. The 3DR cable has a 5-pin connector on the radio side.  I like the 6-pin connector with an empty pin because it reduces the number of ways the connector can be incorrectly hooked up to the radio.

If you do much of this kind of stuff, you owe it to yourself to get the most excellent crimping set from Hansen Hobbies.  Here's some notes on cable making in case you're interested:

(TODO picture of radio end)
(TODOpicture of APM end)

Cable (4 wires)

Radio          APM       Color
-----          ---       -----
1. GND (BLK)   1. GND    Black
2. CTS            empty
3. 5V          2. 5V     Red
4. RX          3. Tx     White
5. TX          4. Rx     White
6. RTS            empty

Saturday, September 8, 2012

Corrugated Carrying Cases

Here's a pretty good supplier that was pointed out to me.  There's tons of them on the Internet, you just need to know what they're called. They come in a couple of size, bundled in packages of 10.

Friday, September 7, 2012

RC Micro World Free Trial

Via rcadvisor, here's a free offer from RC Micro World: Free access to the current issue and past 11 back issues through October 15.

Free Offer link  (username: Neat-Fair, passwd: tempneat)

No foolishness, credit cards, etc.  This will get you logged in and able to download the issues.  A one-year subscription is $24.  The plans are amazing... the image here is a screen shot of a full-size plan.

Thursday, September 6, 2012

Atmel Flashing Tool from HobbyKing

Hmm, this could open up quite a few possibilities.  It's a device that presses down over an Atmel microcontroller and makes the proper connections to flash new firmware.  No soldering onto pads!  Looks perfect for flashing ESCs.  You'll need the USBasp device as well.

Atmel Atmega Socket Firmware Flashing Tool
USBasp AVR Programming Device
eXtreme Burner AVR software

HK describes it thusly:
This genius tool makes flashing the Atmel Atmega MCU found in many ESCs or other devices using Atmega processors a walk in the park. No need to solder or create cumbersome clip on devices, simply connect the socket flashing tool to a USBasp AVR device and place the socket over the exposed Atmel MCU! 
Requires: USBasp AVR Programming Device for ATMEL proccessors.  Suits the Following MCU: Atmel Atmega8, Atmega48, Atmega88, Atmega168, Atmega328

  • Fits Atmel processors that use the "QFP32" package.
  • Doesn't fit AtMega64 used in Turnigy 9x.
  • Doesn't work for SiLabs processors.

Here's a video where hummingbirdRPV flashes four ESC's without even removing them from his quad.

Monday, September 3, 2012

Disabling the built-in GPS on APM 2

Andreas sent me a note pointing me to the procedure to disable the APM2 built-in GPS.

tl;dr: the disable pin is adjacent to GND.  Short them with a solder blob.

Sunday, September 2, 2012

Zephyr II Battery Box

Here's my battery box for the Zii.  I made it for two reasons:

  • I needed a bit more room for these 4000 mAh cells, so I trimmed a bit from the front and back of the battery compartment.
  • Other people have commented that crashes were crunching up the Zii nose, and that a plywood battery box helps prevent this by transferring the crash energy to the rear of the body where there's more foam to absorb the energy.

Here's the cut I made to the the front and back of the battery compartment.  I made it flush with the leading indentation.
Here's a closeup of the front cut.  Ther was some epoxy sealing a gap... I used my Xacto saw blade to cut through the epoxy.
Here are the five pieces of the box.  I routed out two slits for the battery strap.  I don't have measurements as I just marked the cuts against the opening.
I started with the front and back walls, placing them flush against the front and back foam walls.

Next, the bottom.  It sits flush against the front and back walls.  Don't let those boards ride up -- the sides of the fore and aft boards should butt against the bottom board.  See the illustration below.
Finally the side walls.  Also shown are some hinges that I might use to hold the top hatch on.

Here's the side view of the box.  Be sure that the bottom and sides touch the flat surface of the front and back walls.  this will transfer energy from the front of the plane to the back if you nose in.

Saturday, September 1, 2012

JST-DS Walkera 2-Pin Connector

As seen on the Walkera Ladybird (and presumably other Walkera 1S craft).
Vendor is sammylam on ebay. listing here.

Note that some other brand has an identical connector WITH OPPOSITE POLARITY so be very careful in this regard. Here's a nano-tech with opposite polarity.

Update: the polarity of the advertised pigtais looks like it is opposite that of the Walkera Ladybird.