The Blair ChroniclesIt's just a matter of record.

Although another major revision is done, Thunderbird, as I have said on a continual bases, still remains a work in progress.  I want to see what type of feedback I’ll get so I decided to take this video (this is a ~30.7MB file)

I also need to make a few design changes and wanted the pics so I could briefly explain what technical changes/modifications will take place next.

The changes start with the pan and tilt control arms (vertical tilt control arm is black with the 4 screws at the top and is almost centered in the pic). These will be converted to ball and rod links and will eliminate some of the hardware and also tighten and lighten up the assembly.  Also, the angle extension (the aluminum angle that points toward the lower right corner of the picture) for panning the black circular base needs to be trimmed and the control arm mounting point changed so the travel is greater than it is currently (from ~60 degrees to more than 90 degrees). 

The electronics are all constructed on prototyping breadboards which have changed from a very complex system using a Basic Stamp micro-controller to juggle input signals from limit switches to output power to motors that drive pan, tilt, zoom and triggering.  I started with a double pole double throw switch circuit years ago when I did not understand anything.  I knew a motor had to have juice to turn and you could reverse the wires on the + and – terminals to reverse the rotation and that was about it.

It took a lot of years to figure things out and surprisingly, I about turned full circle going from the basic switch, jumping off to complicate things with the Basic Stamp and then returning back to the original idea with educated modifications.  The biggest development came with finding and learning about the wonderful “h-bridge”.  Anybody and everybody who is in the electronics business knows about this jewel like they know the back of their hand.  But, I didn’t.  I do now though and the new circuit consists of motors driven with individual h-bridges that are powered by a 9 volt battery and activated by switches through a transmitter and receiver circuit.  Didn’t need the micro-controller although I really enjoyed learning how to make it do things that were very cool.  (I’m sure the future will bring me some wild idea where I can incorporate a Basic Stamp!)

The final version controls will look nothing like the switch box on the left.  I plan to take a portable aluminum briefcase and mount a LCD flat screen in it along with arcade style push buttons to get that “007″ effect, should make “Q” a little jealous although I think he may be a little bit beyond my “tinkering”.

On the right is a closer look at the transmitter (TX) circuit that I built and which is also pictured above hooked up to the toggle switches.  If you touch the red wire to the black wire the circuit transmits the signal to the receiver (RX) unit which sends a logic signal to the motor h-bridge and turns the motor one direction.  If you touch the red wire to the yellow wire, same thing happens and the motor turns in the opposite direction.  Easy huh?

Just on the left of Thunderbird is the RX circuit which also includes the h-bridges, one unit that contains two bridges and another single bridge unit.  These will go away in the next build session.  I have located a single h-bridge design that is made to replace the circuit panel in a servo.  This will make space much more manageable and provide a cleaner more compact design.  Also, not shown in the picture, is the wiring and video circuits although you can see the camera on the left of the pellet rifle.  This has been and still remains a difficult juggling act between economy, space and picture quality.  (I mention this as a side note on economy because each predator Thunderbird is designed to eliminate has questionable value depending on any one individuals motivation to spend large amounts of money to get rid of them.  I touch on this subject elsewhere and it is worth discussing: how problems motivate people to spend their cash…)

In terms of video it’s worthy to note that what you see in the movies and on TV with respect to a view from a rifle, for the most part, is a special effects view. It is not that of an actual scope or camera or any real combination that contains actual cross-hairs.  The countless attempts I made to achieve this eventually brought the entire project to a stand still, that is, until I happened to stumble onto a fantastic solution. I now have the ultimate solution of which the output video from Thunderbird’s targeting camera shows the full target scene with adjustable cross-hairs at the operators station.  Expensive but perfect.  Combined with controllable 60X optical zoom you can pan and tilt the turret for target acquisition and then zoom in for the most accurate shot possible. 

Another hurdle that had to be solved was how the video would be transmitted and the resulting quality.  Wireless solutions offer problems with quality and obstacles.  Unless you spend more money, your line of sight from the TX control unit to the RX unit cannot have obstacles for the best quality video.  There is also a problem with power as it relates to using hard wiring or having a wireless set up.  You can chew up batteries pretty fast when you leave a camera on for long periods and in my case, this could be periods of hours.  On a side note: this was also a BIG factor in powering the turret pan and tilt motors.  When not in use the positioning had to stay fixed without the use of power unlike radio controlled (RC) servos that use pulse width modulation (PWM), where the pulse needs to be constant from the source drivers to the motor in order for the motor to stay put and hold to any fixed position.  My lead screw design takes care of that problem and also solved the problem of speed.  It was very difficult to come up with the mechanics to get something to move so slow and not stall out a motor yet retain enough power to move the load.  You cannot see the lead screws but if you watch the video it all makes sense.  Just imagine a target 100 yards away.  How far, if you were looking through a scope, would you have to move your rifle to make the cross-hairs move just a smidgen?  Think about this for a minute.  What moves near you a fraction of an inch moves at a 100 yards in distances of feet or yards!  It’s a real testament to how highly tuned human movements can be.  Replicating these finite movements with a few motors and the driven mechanisms is a tough proposition! The only thing left to do here is incorporate an electronic means to double the voltage to the motors so that the speed can be increased.  This option is necessary in cases where a target/s may move or be spread at distances that require movement within Thunderbird’s capabilities but on opposite ends of it’s limitation.  In other words, if you want to pan or tilt Thunderbird to another more distant position versus a lessor distance, you can do so quickly.  Again, the video shows how fast Thunderbird moves.

Speaking of tough challenges, I thought the video cross-hairs would be the demise of Thunderbird until I found a solution by luck in one sense and by stubbornness in another.  It became clear with time the triggering method I would have to build would be equally daunting.  The force needed to pull the Crossman’s trigger was incredible.  The natural pull could be measured at ~7 pounds or so.  To move the trigger about a half inch should be an easy thing to do wouldn’t you think?  It was a great challenge to solve and after a host of attempts I finally reached a combination of mechanical principles that worked.  I still have one more modification to the triggering mechanics to tweak them up to my liking.

I’ve got it all done in prototype form and while the end result looms ahead like a carrot on a stick, I defer any over excitement because I am not quite sure the whole thing will work out as planned.

Up to this point, I have tested successfully individual parts of the whole project but have yet to test a completed system.  This is a big factor because I have Jerry-rigged a variety of pseudo complete systems each one having its own drawbacks.  Some drawbacks were impossible to fix and some I could workaround and in the end I have planned for and made appropriate changes that will be incorporated into the final version.  Until I can finish up these loose ends and finalize construction to a point where I can produce small production part runs based on solid construction drawings, I can only remain guarded to Thunderbird’s final success.  Which seems to beg for an answer of what is success?

Project Thunderbird’s success will equate to a variety of marketable products.  Adjunct or assistive pellet gun products used for predator and pest control and other non-related products that may enhance the abilities of users in the areas of long term, long distance visioning such as security or surveillance, bird watching and other animal or special interest photography, videography and film making, hobby modeling and construction.

Products for purchase upon future and final version release.

1. An affordable complete “plug and play system”.
2. A complete system “parts kit” ready to assemble for the do-it-yourself types that want to save some money.
3. A set of “down-loadable plans” to scratch build a complete system for those who want to save more money over a kit purchase and have the general “handyman” skills to accomplish such a task.
4. Axillary products available as above.  For example: linear motion slides of various sizes, pan and tilt slow motion turrets, short distance force mover devices, visioning systems.

Related posts:

1. On the road to freedom
2. Is it really a viable idea?
3. Motivation
4. Progress takes time.
5. RBS (Tripping Your Trigger)