February 2009 Archives

FPV on an R/C Airplane - eventually...

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Well, I was hoping to get some first person video off my glider, however it turns out that the camera cannot run off the USB cable (oops. Should have tried that first I guess). Via Make Blog, here is a cool site that shows some of what I'd love to get into:

FPV equipment

MAKE Magazine blog entry about FPV hobby

More Golf Dome Indoor flying dates!

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Through the grape vine I have received word of 3 more dates for indoor flying at the Golf Dome. Turn out has been very good at these events, and I encourage anyone who has not yet checked it out to brew an extra pot of strong coffee and make the trip!

Here's a map to help you out!

Flying times are 10:30PM until 12:30AM, however, the dome is open from much earlier on for those who want to practice driving or start the evening earlier at the snack & beverage facilities.

The dates booked are:

Friday March 6

Friday March 27

Friday April 17

Don't forget that the dome is booked this Friday (February 20th) for flying as well.

Binary Clock - Part 2s

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I started building a binary clock (nearly a year ago). I had some surplus 7490 and 838 decade counters. These are TTL I believe and seem to have no problem driving LEDs through 150ohm resistors. I have a divide by 60 circuit that takes the 60Hz AC and produces a 1Hz clock. This feeds another 838 which is connected to a 7447 that is driving a single 7-segment LED. My last 7490 is in place to drive the 4 LEDs that will display the 0-9 minutes.

I ran out of parts :-( Here's how far I got:

binary_clock_progress.JPG Since then I received a bunch of 74C90 - CMOS variety chips. I cannot seem to get these to play nicely. I have discovered that CMOS inputs require pull up resistors, and now I am hearing that they cannot (or should not) be used to drive LEDs directly as the current is too much for them. Hmmm.. Would like to keep the part count down if I can.

Anyone willing to trade 74C90's for TTL 7490s??

I'm trying to have 2 x 74C90s count 0-59 (in binary). I have a clock line coming off my circuit board to the prototype board. I can get one 74C90N to count 0-9, however, the second 74C90N does not want to count to 5 consistently. If it does anything, it counts 0,1,2,3,4,5,4,5,4,5,4,5.....

It appears that the QC bit is turning off then back on very quickly during the reset because if I use the QC bit to drive the first 74C90, that one counts even though QC looks like it stays high.

This is my prototype mess:


(Hmm... just had a thought - I have some 4050 buffers - would they be more suited to driving LEDs???)

Any advice would be appreciated! Thanks!

Sophisticated Lady Upgrades - Video???

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So I'm pondering a new plane for the spring / summer and realizing I don't have a lot of cash...

Late last summer I had put the motor and radio from the Sophisticated Lady glider / sailplane back on the original donor (MicroWhiz). However, that did not turn out so good as I'm not quite ready to take on a fully acrobatic airplane. I also tried a couple high-start launches with the glider, which was neat, but again the flights are just to short for my liking. Ridge soaring off a high-way overpass is probably not the best idea either - even though I probably have a lot more skill now then I did when I first tried.


As a result, I decided to put the motor back on the glider and get it ready for summer. Along the way I took a good longing look at the little servos in the MicroWhiz and compared them to the big standard servos I put in the glider. The weight savings can't hurt and given their location, reducing the weight might make a slight improvement in the Center of Gravity.

Looking down - I use some thin plywood strips to create new mounting points at a right angle to the original mounting points.

Look at all that SPACE!

In the process of transferring the servos from the MicroWhiz to the Lady, I picked up a couple tricks. The main one being installing the EZ-Connectors.


These at the little posts that clip to the servo control arm and have a set screw to clamp onto the push rod leading to the control surface. The challenge with these parts is the grommet that holds the connector in place is a tight friction fit and needs to be pressed on far enough for the shaft to stick through / past. They are too tiny and tight to get together with my fingers, and pliers will only get the shaft flush. Scrounging through one of my many buckets of junk I spotted a simple hanging hook / hinge. It is basically a small piece of thin metal folded in half with hole drilled through for a mounting screw. The hole was small enough to prevent the grommet from falling through and the metal thick enough to provide the room for the post / shaft to come through.

Now I could use the pliers to quickly press the pieces together.

EZConnectorWorkingIt.jpgOne other snag is the control arms do not have large enough holes by default for the posts. I had to enlarge them slightly to fit. Make sure that the connector can turn when in place. Once in place, there were a few minor adjustments and of course trimming that I went through. I had to reverse on of the channels on my transmitter. Final trimming will have to wait until I get out and airborne.

Next step - Video!

I would really like to try some POV video with a plane. I bought my son a cheap (really cheap) digital video recorder and have rigged up a mount for the lady. Assuming I can get balance and power issues worked out, expect to see some grainy video this summer!

In this picture you can see a bolt with a number of nuts threaded on. This was part of the nose weight to balance the plane properly (along with a 1oz fishing lure). I am hoping that the weight of the camera (it is quite light) will be sufficient to provide the forward CG I need (the tail has a lot of glue and is quite heavy).

I am hoping I can power the camera from the main flight battery (I realize this is risky - but I'm trying to save weight and will monitor power consumption closely). It normally requires 4xAA batteries, however in playing around with its 'web cam' mode, I observed that it will run off the USB connector (once started I removed the batteries and it stayed running). A simply 7805 regulator circuit will weigh less then 4xAA batteries. I have not confirmed, but it may also be possible to simply tap into the receiver/servo power supply from the speed controller and use that.

Stay tuned!!

Tri-plane repaired!

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Remember this little gem???


Back in November, this neat little Tri-Plane met a 3D head on and shattered into many pieces. I thought that was it.

However, last Friday it was BACK!


Can't really tell from the photo, but this is the one! The wings have definitely been glued back together. I actually saw it buzzing around the golf dome! So way to go to whoever owns it and had the patience to put it all back together!.