Wednesday, June 1, 2016

Bringing an Airhogs Aero-ace back to life Part 2

I received the new batteries today. They are labeled as 250mAh, but listed on amazon as 200mAh. The capacity wasn't really the major concern, it was the weight. These actually don't feel that much heavier than the original battery so I gave them a shot.

I decided to replace the lead wires coming from the board since the originals had been moved, soldered, and de-soldered so much.

Before I did this however, I did want to test that the battery voltage safety circuit that came with the new batteries would work with the aero-ace. Most of the circuits on these should be identical. They have a dedicated voltage monitor that will cut off the battery if the voltage drops below a certain threshold. It is  great feature for little aircraft like this where there is practically no risk of damage if the power cuts out mid flight.

Voltage output seemed good, the battery was at least stored correctly.

It was time to solder the new battery into the board and check it out!

Power switches turned on, throttle all the way up! ....nothing. Really? Damn.
Nothing was responding, the transmitter was inches from the airplane, antenna was connected, voltage on the board was correct and nothing looks immediately out of place or wrong.

I checked everything that I had touched, or come close to with my soldering iron 3 times. There is a fairly large diode on the board that is, as far as I could tell, reverse voltage protection, so even if my battery was backwards it shouldn't have damaged anything.

As a last ditch effort, I was actually able to dig through my old electronics drawers and find one of the "old" aero-ace receiver boards. (I think of myself as a high functioning hoarder, although I haven't come across many electronics engineers that aren't, so at least we have a community) It is identical to the "new" board, the channel selection pads are even configured the same (Channel C in this case).

Soldered in, everything double checked, all switches on, throttle up!  .....Double damn.

So it was a long shot, this board had been sitting in that drawer for 7+ years, and I have no idea what I did to it before it actually ended up in there. I was pretty discouraged at this point. The thought had crossed my mind several times at this point that the problem may actually be in the transmitter. I even went to try to view the output on my scope. Unfortunately, the display on my old analog scope isn't working.

Ill let it sit on my bench for a few days, and stew over it.


Bringing an Air Hogs Aero-Ace back to life Part 3 (Update)

So, it was last summer when I was messing with fixing the air-hogs Aero-ace airplanes. From what I remember, I was somewhat successful at getting the new batteries installed and charged. My problems came from the batteries being too heavy, and not getting much more than a somewhat controlled glide out of each plane even at full throttle. It was fairly discouraging, and at the same time, my friend had made a foam board RC airplane that was much more fun to fly. (Not too surprising).

I decided not to mess with them much more after that. I assume that there is a lipo that is fairly easily available that would work, but for me, it just wasn't worth it anymore. The larger, but more maneuverable, foamy really inspired me to finish the laser cutter to make more foam RC planes.

Who knows, I may return to these, they are still sitting on a shelf in my garage. Flite test has done some cool video's on micro RC planes in the past, and these air-frames would be perfect for the same micro control electronics.


Solid State Laser Engraver Overhaul

I had a lot of free time on my hand when I was laid off in January of 2015. I needed a project to work on to keep myself from going crazy while I was still looking for a job. I have a tendency to have about 15 project ideas floating around my head at any given point, a side effect being buying random parts for any one given project over time, and then those parts lying around for a while. It makes having all the parts I need for a given project already in my work-space a common occurrence. This was the case for my laser engraver/cutter. I had at least 90% of the hardware that I needed to build the project, which was good because I had to keep the cost moving forward to an absolute minimum. Here is the final result.


Yeah I know, not very pretty.

I use ball bearing drawer sliders, and Nema 17 stepper motors with direct drive 1/4 20 threaded rod. The main structure and all connecting pieces are made of 3D printed parts and 3/4" square aluminum tubing. I use a "2.5W" 405nm laser diode. It works fairly well, but has a small working area and banding problems. Even with these short comings I was able to get a few fairly useful projects out of it. I was able to engrave my name in leather for a couple cases. I also helped my friend cut out poster board stencils used to make road markers for his wedding. I also used it to make a custom Munckin board for my wife. (Not perfect, but still pretty cool)

I was never completely happy with its limited use, and have been wanting to remake it larger, and more capable for several months now.

These are my general guidelines:

1) Get rid of the threaded rod and use belts
2) Increase the work area to fit a sheet of dollar tree foam board
3) Increase laser power (Still solid state, more on this later)
4) Improved ventilation
5) Be able to make grey-scale images (Raster Etching)
6) Software controlled laser power
7) Laser Z-axis control for material differences and multiple pass cutting
8) Improved control hardware enclosure and functionality

Going with belts makes it significantly easier to increase the functional area of the laser, especially with 3D printed parts. It also makes alignment easier, and speed at which I can move the laser head. I am going to use some parts that were designed as replacements for my solidoodle 2 for the longest axis. They use (bearings from amazon)

I am currently using GRBL on an arduino for control, and have been happy with the performance and ease of use, so I don't see a need to change. There are also distributions for the raspberry pi that are made specifically to interface with GRBL and use a web interface. This is also the direction I plan on taking, eliminating the POS macbook that I bought for 100$ 5 years ago. Yeah, still regret that decision, but it was a functioning machine I could leave attached to the laser.

Update (6/1/16):

I started this blog post several months ago, and like many things it has sat unfinished for quite a while. Recently, I have made significant progress on the cutter and am pushing myself to somewhat document what I have done on here.

The next post will contain as many pictures as I have of the progress so far and how things are progressing.