Archive for the ‘Unipit’ Category

new toner transfer method

I was having inconsistent results with the Press’n'Peel Blue toner transfer film using an iron, so I thought I’d try a different tack. 2 G-clamps, a thick piece of nice flat aluminium, two solid pieces of wood, and make a clamped sandwich with the flat aluminium against the PnPBlue, and the wood spreading the clamp pressure evenly. The whole thing went into the oven at 150deg C for 30 minutes. The results:

only a couple of transfer problems, touched up with a PCB pen
board1 (51k image)

clean! Ammonium Persulphate, do your stuff
board2 (29k image)

teeny bit of dremelling where my PCB pen touchups were a little enthusiastic, and it tests well
board3 (56k image)

so here it is

cheesy enough for ya?
pit_aug09 (48k image)

Work’s progressing nicely on the pit for the expo. I’m deep into the PitManager software now, and it’s getting a good refactor as I’m building it to best OO practice.

Work on the HSI has stopped for now, but that doesn’t mean I’ve stopped thinking about it. After the expo I’m going to build a VSI and RMI/Compass, to practice the skills I’ll need to realise the HSI. The design is pretty tight now, I have access to gear cutters for the ring gears (if I ask Scott REAL nicely!) and all that’s left to do is prototype it.

MCSSOH working again

Well, this was weird.

After extending the wireless doorbell receiver away from the MCSSOH module via an ethernet cable, it didn’t work. When I took the cable out of the loop again, it still didn’t work.

Uh oh, I broke something.

So I did a bit of poking around and determined that there might be some sort of issue around the rectifier, that was intended to take the AC signal through the speaker wires and convert it to DC to drive the PIC pin. A bit of googling revealed that someone else had done something similar using a reed relay rather than a rectifier.

So, I pulled the rectifier and put the reed relay over the AC pins (using wires out of the existing DIL socket), leaving the DC pins unconnected, just to see if the relay would be closed by the doorbell.

Not only did it close the doorbell, it lit the SSOH lamp! With the PIC pin completely disconnected from everything! Wtf?

All I can think is that the inductive load on the doorbell has somehow compensated for a fault elsewhere in the circuit and by some coincidence two wrongs are making a right. I will be totally unsurprised if it just stops working sometime in the future, but for now I gaffer-taped down the reed relay, closed it up and re-mounted it in the pit :) The missus is happy that she doesn’t need to traipse down the stairs to get me late at night if I have my headphones on.

great source for cheap steppers

Thanks to Scott Hendry for the link.


Cool article on using light-dependent resistors to sense movement in small ranges (example uses an F-16 high-G HOTAS).

candidate PCB

Herewith the first cut of a 6-way PhidgetLED64 lamp driver PCB: {{popup pl64lad01_01_PCB.gif pl64lad01_01_PCB 677×720}}clicky

And here is apparently the best toner transfer paper for printing PCBs:

*edit* Luckily a very kind gent on the AllAboutCircuits forum picked up an error with the board – the jumper pads should have been connected to the MOSFET sources, not to the #6 pins. Doh.

{{popup pl64ldv2.gif pl64ldv2 660×699}}clicky for final version

converting a PhidgetLED64 to drive 12V lamps

My Master Caution and targeting Mode Control Panel illuminated switches have a 12V lamp in them, which can’t be driven directly by my PhidgetLED64 which is designed to have directly connected LEDs. So – after much mucking about, the following:

your mileage may vary depending on the qualities of your lamps
pl64ladr (3k image)

hoping the magic smoke will stay inside
pl64ld_01 (48k image)

it’s alive!
pl64ld_02 (48k image)

review – Building Recreational Flight Simulators

I make no secret of the fact that I’m a huge fan of Mike Powell’s website ( and first book, Building Simulated Aircraft Instrumentation (BSAI). Mike’s site was both inspiration and assistance to me in the early days of building my cockpit, and though I’m yet to finish building any of the specific instruments from BSAI (parts are still sitting on my workbench!) it’s been an invaluable resource for other cockpit projects on PIC programming and other topics of which I had little or no prior knowledge.

So I’ve been waiting excitedly for Mike’s second book, Building Recreational Flight Simulators (BRFS). And last week it finally arrived, delivered right across the Pacific Ocean nine days after my painless and quick Paypal order. So: what is BRFS like, and what does it offer the beginner and more experienced pitbuilder? These questions, dear reader, I hope to answer for you.

Book 2 is a more generic look at simulator cockpits than Book 1 (the clue’s in the titles). While BSAI was a deep dive into DIY instrumentation for a flight simulator cockpit – air core, stepper or servo-driven, with digital or analogue electronics – BRFS looks at the entirety of the pitbuilding hobby. Topics covered in detail are:

- Joysticks, control yokes, pedals and engine controls (the primary interfaces with the simulator)
- Position and force sensors
- I/O and scenery display
- Computer drawn, flight-rated and DIY instruments
- Panels, switches and warning/status lights
- Interfacing with Microsoft Flight Simulator
- Sound
- Enclosures and motion/force cueing
- Precision layout, printed circuit boards and microcontroller programming

Most chapters follow a similar format. Mike starts with some context in real aviation, how and why replicating that function might augment your flight simulation experience, discusses some options for building or purchasing the necessary components, and finishes with a construction project designed to provide a practical foundation for one’s own specific cockpit needs. If you build every project in the book, your cockpit will be impressive to say the least!

The engineer in you will be delighted with the plethora of excellent line drawings. For a visual person like me, these are a great way to consolidate the topic. Additionally, Mike has introduced printed circuit board designs, which will save you a great deal of time if (when!) you construct your project. I also have it on authority that the electronic versions of these board designs may be made available to purchasers of the book, for use with board fabrication shops. If you’re not delirious with excitement at the prospect of dipping boards into hot caustic liquid to etch them yourself, this may be of immense value to you!

Where necessary, full PIC assembler code listings are provided in the book. Again, there may be soft copies of this code made available in future to avoid typing errors. I’ll update the review if these become available.

Mike’s referencing is expansive. Every chapter includes references to community, commercial, online and literary sources of products, techniques and information that is relevant to the topic. He is careful to avoid any endorsement of specific products or vendors, fitting for a book that is more encyclopaedia than opinion piece. I am particularly glad to see that BRFS references suppliers outside the continental US, for example Maplin in the UK and and my local (in Australia) electronics chain, Jaycar. The author has clearly embraced his growing international audience.

Putting the content aside for one moment, onto Mike’s writing. He seems to have matured – and relaxed – as a writer since BSAI, and the book is authored in a style that makes for easy and even entertaining reading; rare for a such a technical tome. There are 180 footnotes in BRFS, often dryly chucklesome and worth a skim read in themselves. An example:

“Recreational flight simulation ranges from sitting in a cardboard box pretending to fly 15, to … “
Footnote: 15I’m fairly certain I’ve outgrown this stage.”

These and the general conversational style help to make the reader feel that they are enjoying a discourse with an equal, proud geek to proud geek, without any sense of being lectured by a superior intelligence (though Mr Powell is undoubtedly that). Whether you end up diving into specific sections as a reference, or sitting in the bath and reading it cover to cover, you will find the book’s structure accommodating. The writing is clear, grammar and punctuation are spot on (often a risk with self-published works) and the printing and binding first class.

I’m sure there are excellent reasons behind sticking to a treeware-only format (rampant copying being foremost no doubt) but a searchable PDF version would be extremely useful when searching for a particular keyword or reference. If I hear from Mike on this topic I’ll amend the review.

So: the audience. Let’s start with the nugget; the newbie to cockpit building. If you’re anything like I was, you are now bewildered with the amount of information on the toobs and wondering where to start. You may even be feeling that you don’t and will never possess the skills to build something yourself.

For this person, BRFS represents a distillation of the information cornucopia that threatens to induce “analysis paralysis” and that in itself makes it excellent value. The beginner may tend to rely more on commercial products than home-built for their first pit, and this is perhaps the one area where you may feel that BRFS has gaps in detailed content. However, given the incredible range of commercial products and simulator software products, it is quite unreasonable to expect the author to cover them all, and BRFS will at the very least appraise you of the existence of most of them which is often half the battle. More to the point, it will reassure you that it is possible to realise even your most fanciful simulator dreams, and that you can develop the knowledge and skill to do it yourself.

It would be easy for me to say that much of this book is not for the electronic or mechanical beginner, given the excruciating detail on such arcane topics as microcontroller assembler code, serial port communications, precision construction and many other heavy technical topics. However, it would be fairer to say that it is not for someone who wishes to remain a beginner. The important thing is the mindset – if you possess an interest in what makes these fascinating devices work, and are intrigued rather than frightened by lofty heights of understanding, you will get a great deal out of this book regardless of your current knowledge. I am living proof that it is possible, in a short space of time and using Mike’s books as a catalyst, to go from zero understanding of PIC RISC assembler to being able to design and build my own applications – and I am by no means spectacularly gifted, as my wife will happily (and vociferously) attest!

For the more grizzled simpit veteran, BRFS offers a number of things. There are specific projects that may be of great value to your current or future pit (in my case the RS-485 I/O bus and the LCD radio heads) and many of the projects may have at least passing relevance to something you’re working on. The more we fly our pits, the more we are niggled by their little limitations, and BRFS will drive you (and give you the blueprint) to at least consider building something that does exactly what you want rather than settling for what’s commercially available.

In addition to that, you may find it simply a fascinating read. Don’t underestimate the simple joy of reading something written by a like-minded individual, aimed squarely at your own passions. You may even learn something!

I’m sure by now that you’ve realised that I like this book. I like it a lot. It is a quality product, well written and rich in content that is, if you are reading this review, directly relevant to your interest in flight simulation cockpits. I can’t think of a flight simmer with an interest in pitbuilding who would not get at least their money’s worth out of it.

If I may wax lyrical for a moment: I am notorious for supporting flight simulator products for little or no better reason than ensuring that they continue to be made. The high-fidelity sim market is a tiny niche, and when compared to the quick-fix console market, is not particularly lucrative. If you have no other reason to purchase BSAI and BRFS (and make no mistake, there are many good reasons to!) consider it simply because the future of our hobby depends on us – individual simmers – supporting quality products with our hip pockets. Otherwise, you may find yourself reading “Super Awesome Jet Combat Extreme VI (PSP3) for Dummies” in the near future because there are simply no better options.

Lecture over. Great book.

Building Recreational Flight Simulators is available from for US$59.95 plus P&P.

tactile feedback for slip

I was chatting to huggybear the other night about the balance in DCS:BS, and how there is no real feedback on slip other than looking down at the balance ball – which in my case is usually fully deflected left or right.

So I got to thinking that it would be cool to get some tactile feedback. Now IRL when you slip, you feel it in the pit of your stomach and in your inner ear canals. How to replicate that? The initial idea is to use motors (e.g. this) with an asymmetric flywheel, similar to what is done in mobile phone vibrators. Mount one on either side of the seat, near the kidneys. then, take the LoGetSlipBallPosition() output from DCS (which returns a value of -1 to +1) and pipe that to my custom PitManager software, which in turn pipes a value from 0 to 99 to two outputs on my PhidgetLED64, one for left and one for right. Sync the motor speed to the current coming out of the Phidget (from 0 to 30mA depending on the input value) with all sorts of isolating and amplifying wizardry and you have vibrating kidney sensors that give proportional feedback to remind you to step on the ball.

Problems: choosing motors and flywheel sizes that will give noticeable feedback, but won’t shake themselves apart; building a properly isolated circuit that can be driven by the PhidgetLED64 (my only output module); not burning down the house or causing myself permanent kidney damage.


*edit* on further thinking, the sort of bollocking around I’d need to do with the PhidgetLED64 is astonishing. However… this. Perfect. And much neater too, if I end up selling the kits as HuggyBear suggested!

*edit 2* On even further thinking, what about the TN Games bullet vest? It has a C/C++ SDK so I can code directly to it.

X52 spring mod

I was getting the royal shits hovering in DCS:BS with a strong centering force on my X52. Now, by the standards of the old X45, the X52 is positively silky, but for a helo it’s like nails down a blackboard every time that centering cone locks in place.

So, with the aid of three plastic zip-lock ties, I compressed the spring which has done a nice job of reducing pressure in the center for fine hovering control, but retaining pressure at the edges for tactile feedback that it’s time to trim.

Start by not tightening them all the way, and play with it a bit. You can keep tightening them around one spring loop until it’s just the correct tension for you. I initially tried taking out 2 spring loops, but the stick flopped around and flying on Route mode required constant effort to maintain the cyclic in the centre, which kind of defeated the purpose.

3 zip-locks, evenly spaced
pit_x52springmod (38k image)

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