Apr 052016

Hi, my name is Darren and I’m a serial hobbiest.

Well maybe not that bad, most of my hobbies are pretty much related (electronics, computers, science), and a lot are things I’ve been interested in since I was a kid. Most recently, I’ve invested in a fairly decent telescope and mount to do some visual astronomy, but more for astrophotography. I want to take pretty pictures of things very far away! So after a lot of reading of various blogs and websites (Star Gazers Lounge forum is fantastic), and watching numerous youtube videos, I got a tripod for my camera and a couple of cheap lenses off eBay. That is all that is needed and you can get some half decent shots.

My astrophotography album

But it wasn’t enough. So I dove back into the forums and did even more research, and learnt a few important things.

  • Telescope – Numerous different types, mainly split into reflectors, refractors, and catadioptric. All have their benefits and downsides, but for doing astrophotography the telescope isn’t the most important item surprisingly.
  • Mount – This, for astrophotography, is the most important thing to get right.You need to have a solid mount for doing anything more than a few seconds exposure, and one with tracking in Right Ascension at least, to track the stars. And it really needs to be an equatorial mount to avoid rotation of the starfield as it rotates.
  • Eyepieces – You need eye pieces to view through a telescope, and the shorter the focal length, the greater the magnification. These are generally only used for visual astronomy, as cameras bypass the need.
  • Camera – Most DSLR cameras block out a large part of the infra red by design, but you can get them modified to remove this filter and get much more vibrant images. Its not a necessity, but definitely a nice to have.

Whilst learning all this, I had a thought in my head about some form of computer control (Linux based, of course) and actually stumbled upon a few projects to help with this. The first was AstroEQ which was an opensource ‘Goto’ system (select a star, and the telescope will automatically move to center on it) designed around an arduino. That was a perfect start for me, and I was pretty sure I could get it working from Linux. Thats when I discovered indilib!

Indilib is an open source system for controlling all sorts of astronomical instrumentation, not just goto mounts, but also things like auto focusers, digital camera, filter wheels, and other custom devices you may want. Even better, all this can be run from a Raspberry Pi as the control server and a laptop using the actual astronomy software. This would mean I could set it all up, and retreat to somewhere a little warmer to actually do my observations and photography. I’m sure this is against the amateur astronomers code or something, but damn it gets cold out there.

Along with indilib, there is kstars. This is a planetarium program written for the K Desktop Environment, and with EKOS plugin can control any indilib hardware. Not only that, it can schedule work and sequences, and help you plan your observations.

I’m going to (try to) write more blog posts chronicling my progress on getting all this set up, and some HowTo posts on using indilib on a raspberry pi, with kstars, and any custom hardware I make.

Dec 042015

11934535_10156061505195316_3190924556943319116_oIts been a long time since an update, but we moved house at the start of the year and things have been hectic. At least, thats my excuse and I’m sticking to it! I have been making progress with R2 in the last couple of months, doing a lot of work on his brain for starters, and painting various parts.

Code wise, there has been a couple of fairly drastic rewrites since my last update. The interface is a REST API, which sends commands to various modules as before. I’ve added a scripting module now, so that scripts or loops can be initiated such as random sounds, or a dance routine. The servo module had to have a major rewrite too as I discovered that I could only control one servo at once and had to wait for that to finish before another command could be sent. That wasn’t much good! I’ve also written the first of the actual controller interfaces (not counting a simple web one for testing), R2 can now be controlled from a PS3 controller. Button combos are read in from a csv file to trigger certain effects or scripts. Lastly, R2 now has a voice, and can play any mp3 stored in a directory, including selecting random ones from a list of types. Next step is to get either the Pi or the A la mode Arduino to control the speed controllers. I don’t want to run them off the Adafruit i2c servo controller for safety, I’d rather drive them directly and have some form of watchdog to make sure R2 doesn’t go on a rampage. All the code is still available on GitHub under my user, dpoulson

The PDU also needed a rethink, not least of all because of the amount of current it needed. The setup now has feeds directly to the speed controllers, with relays on the output from them to the motors so I can break the circuit if needs be. These relays will automatically turn off if the battery is disconnected so that any pushing of R2 will not feedback into the speed controllers and fry them. The relays will also be controlled from GPIO pins on the Raspberry Pi so I can disconnect them via an API call. I’ll also have an input for a kill switch that will have to be permanently on if any of the motors are to be powered, possibly using a transmitter in a replica droid caller or hilt of a light saber. I’ve a base idea for the new relay controls:

Powerswitch The relays I’ve found are Omron G4A-1EA, which have the benefit of the switched load being on spade connectors on the top, rather than through PCB traces, which when I did the calculations would need to be massive to support the potential current running through them. This allows me to make a simple PCB with the controller circuit, and hook the 24V battery up to it to power the coils. If the battery is removed, the coils turn off and the circuits are broken. No fried speed controllers.

The 24V connection will probably go through the fuse box I’ve installed, with a hefty fuse. The makers of the speed controllers don’t actually recommend a fuse but I’ve seen a few comments saying a 60+A fuse can’t be a bad idea, just in case!

The battery will connect directly to the center contacts of a DPDT switch, with the fuse box on one side, and the charger connection on the other. This will allow charging the batteries without taking them out of the droid. Not sure if this is best practice or not, needs more research. Currently they are just a pair of 12V SLA batteries that I had, connected in series to give the full 24V.

I’m hoping to get some time either this weekend or next, to hook up the motors, speed controllers, and battery, to test them out and get an idea of potential current draw. They’ll be controlled with a standard RC transmitter/receiver for now. If I can get the legs onto R2 he may even be drivable by xmas.

Fingers crossed!

Nov 242012

So, the other day a large crate arrived on my doorstep.

Frickin laser!

Hmm, what could this be?

Yep, I treated myself to a new toy. A 40W CO2 powered lase CNC engraver/cutter (Model K40-III). Now, this isn’t exactly a top of the line model, infact it is probably the cheapest you can get one without going down the DIY route. It is a very cheap device from China, with the most basic of functions. Basically an X/Y axis with a couple of stepper motors, a 40W laser, and a very basic controller board. The main drawback (besides all the instructions being in Chinese) is the fact that it will only work with the rather rubbish software that comes with it, and that will only run on Windows XP. That isn’t going to work for me, especially after finding an old XP laptop and trying the software out. To say that it is buggy and un-userfriendly would be an understatement.

Thankfully, I knew this before purchasing it from eBay. There is a great open hardware project call LaOS, which is designed to replace these cheap and nasty controller boards on these types of lasers. So, armed with a PCB from the project, a bunch of components, lots of pictures of the existing setup, and my trusty multimeter, I am going to set about installing a nice LaOS board. The benefits of this new board is the fact that instead of the machine being controlled from a host machine via USB, it becomes effectively a network printer, controllable from a linux machine as a Cups based printer. This way, programs like Inkscape to draw the desired output, and send it to the machine. A much easier way to control it.

An LCD display with local controls is also available as an addon to the main LaOS board. All in all it should turn this cheap basic machine into something fairly usable. It should then be able to compliment my printer for making things, and Joy should also be able to use it for some of her arty stuff.

So, first stage was to do a few tests to make sure it had survived the journey and was in a working condition before I break it. The front panel has a handy laser test button to let you fire the laser without having a computer hooked up. Needless to say, after hooking up the water pump to cool the laser, I had a bit of fun burning things! 

Frickin laser!

Seems to be working ok

And with it hooked up to a computer with the rubbish software

Frickin laser!

About the best I could do with the software supplied

All seems good, so time to take it apart! Hopefully the next post will have a nice success story of a much improved machine

Frickin laser!


Frickin laser!


Frickin laser!

Thats a 40W Laser








Second part is here

Apr 042012

I got a nice parcel delivered today. Two nicely build hotends for my new Prusa Reprap. After all the issues with the Huxley, the Prusa has been a total doddle. The last piece I needed for it was a hotend, and after having some issues sourcing some of the components, I had a look on eBay for any pre-built ones. I found one guy shipping some from Poland that looked perfect for what I needed, not only did they have all the molex connectors already done in a way that is compatible with my Sanguinololu board, but he was offering a twin pack with one .5mm and one .25mm nozel. Oh, and a pre hobbed bolt too!

Prusa build

So, with the body built and the electronics tested, all I have to do is figure out how to attach the hotend and I can start building. I’ve already posted a video a few days ago of the body moving nicely, which is further than I ever got with the Huxley. Never know, maybe by this weekend I’ll be able to print something! Just have to finish work first.

Here’s the video of the first test of the electronics.

Prusa build

Jan 272012

The replacement electronics for my Reprap Huxley arrived today at long last. I’ve had them plugged in for nearly an hour over dinner, and no flames. Good start!

I think this evening and weekend are going to be devoted to trying to get my printer working. I hope nothing else turns out to be faulty with the kit I bought. I’m already very disappointed with the quality of it overall. If I had a better understanding of the whole Reprap process, I would have gone with just ordering the plastic parts from somewhere and building my own. I’m sure I’ll do a full write up on it at some point.

To recap, I’ve got the frame built with all the stepper motors mounted and the belts in place. So all(?) I have left to do is:

  • Calibrate the electronics
  • Finish the extruder – Just needs the motor mounting I think, and the tube inserting.
  • Finish the hot end – All gunged up, just needs the electronics attaching to the nichrome wire and thermocouple.
  • Mount the hot end
  • Mount the end stops

Once all that is done, I may actually be able to start testing. The testing is going to be a long process I think, I very much doubt I’ll be printing quality objects from the start. Lots and lots of wasted plastic doing test prints, levelling the base, etc. Still, if I can finish this weekend with an actual printed object I’ll be happy. Roll on 5pm when I finish work!