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Archive for February, 2018
Posted by blitzen | Feb 27, 2018 @ 01:11 PM | 4,923 Views
This modification requires a little soldering skill and doing goofy stuff like this requires a HAM license.
Take a crumby toy and fix it so that the signal is efficiently transmitted. A center fed dipole has a 2.1 dBi gain. Theoretically it should send the signal twice as far as the original. In reality, it does better. An omni-directional antenna held vertically emits an almost perfect doughnut shaped radiation pattern. If the dipole is turned horizontally, the radiation pattern shows the signal strength is in front, back and most importantly up in the air. There is no strength side to side but we can easily change the direction we are facing. RF is wasted as some of it is traveling behind us and towards the ground.
The tools are a small soldering iron, electrical solder and flux. A small wire cutter, finely calibrated ruler and an exacto knife. A drill to make 2 small holes (each slightly off center) in a popsicle stick.
The scavenger hunt. A length of thin flexible coax cable measuring at least 17.5 cm. That cheap audio cable from the broken Hi-Fi or VCR will do nicely (RCA plugs removed). Solid conductor telephone, doorbell or alarm wire. 2 pieces cut to 31mm. A bit of string or a mini plastic cable tie. Sticky tape and a clean popsicle stick.
Note: The insulation on the coax is soft and melts very quickly. It's tricky to make a solid join without melting the dielectric. The two 31mm wires should be positioned with a slight air gap between their ends.
Posted by blitzen | Feb 26, 2018 @ 10:30 AM | 2,591 Views
A middle aged woman comes in and buys a complete FPV multi rotor RTF set of moderately good quality. This was a present from a wife to a husband. She explained that her husband already had experience with a “camera drone”. The outfit was costly as it included all the components and accessories. A day later, the woman returns. I thought it was something trivial but it was a request for another “drone”. She said, “It flew off into the woods five minutes after he got it. We couldn’t find it”. I was curious as to who’s idea it was to get another. I didn’t ask but during the conversation I became very suspicious that the “drone” wasn’t for her husband at all. So, I suspect a suburban housewife is sneaking off with her “drone” while the kids are at school. I wonder if her husband knows.
Posted by blitzen | Feb 11, 2018 @ 08:59 AM | 3,609 Views
This question I still see so often answered incorrectly. Do I need a FCC license to use an FPV transmitter? To answer that question correctly, I’ll quote directly from a portion of an article in the April 27, 2017 Model Aviation column titled FCC Concerns by Tony Stillman. My reason and concern is that misinformation might dissuade a novice from flying as licensing may be too much to swallow at first.
"Typical model use today would be in the areas of FPV drone or fixed-wing racing. A commonly used frequency is 5.8 GHz. In order for an unlicensed person to use this frequency band, the FCC only allows specific power output maximum levels.
In this case, they use a complex calculation based on the measured output of the device from a specific distance away. If the device falls below a certain threshold, the FCC requires an FCC identification number on the device itself. This marking indicates that the transmitter can be legally operated without a FCC license.
These items have been tested and determined to have low enough power levels, and a fixed antenna as part of their design, so that they will not be an interference threat to other users. Typically these will be 25 milliwatts (mW) of power or less, but the actual determination process is complicated.
However, if the item’s output power is above this level or the antenna is replaceable, there will not be an FCC identification number on the product, and it will require the proper FCC licensing to operate."
Posted by blitzen | Feb 10, 2018 @ 11:02 AM | 3,644 Views
As far as the hobby goes, I had a bad day yesterday. It seems everything I touched turned into a steamy pile.
I just couldn’t get it together and busted up a quadcopter on the first pack. The bottom frame part, 3 props, 1 ESC, 1 motor, CMOS cam and FPV antenna are all broken. It was interesting to watch the image sensors burn up. It looked like blood slowly dripping down the screen. Unfortunately, the goggles weren't recording.
Starting the repair job late at night was a disaster. Blurry eyes, clumsy fingers and bad decisions. I should have waited. Stress and fatigue made everything worse.
I haven’t gone back to take a look at it this morning. I think I’m just going to sit here for awhile and enjoy a late breakfast.
Posted by blitzen | Feb 05, 2018 @ 01:49 PM | 2,827 Views
A package of BetaFPV 40mm 4 blade props came in the mail yesterday. They are replacements for my ducted (75mm) frame kit's three bladed props. Fitting on a 1mm shaft, they are to be used with either 0720 or 0820 brushed motors. The benefit is increased lift. I felt a change in the throttle immediately on take off. During the flight the throttle position was generally lower than before. This is an inexpensive upgrade that really works.
My hope was that getting these might lessen or change the pitch of the annoying noise the quad makes. Unfortunately changing the props has had the opposite effect and the quadcopter sounds even more bothersome to me. Flying in my apartment, the noise level is unacceptable. Before I dismantled the quadcopter, I wanted to answer some unknowns.

Experimenting with 0720 Brushed Motors
Changing to a “better" motor brand was a waste of time and money. While on the bench, the new motors ran slightly smoother. There wasn’t any noticeable difference once the props were attached. Maybe they will be longer lasting than the Apex 17500KV motors but I doubt it.
A set of generic unrated 7mm x 20mm motors were slower but had just enough power to get the job done. I didn’t attempt flips or rolls. Almost as expensive as faster motors, choosing the faster makes sense.

Experimenting with 40mm, 4 Blade Props
According to physics, cutting 2 blades off of the 4 blade props should decrease lift. I’ve tried it and it does. So, I wouldn&#...Continue Reading
Posted by blitzen | Feb 01, 2018 @ 11:56 AM | 2,615 Views
My junk draw is deep. It holds miscellaneous pieces and parts stripped out of things that quit working. I was in there looking for something and while rummaging through it all I got distracted. After a few minutes, I found enough stuff to build a small FPV quadcopter.

Because some solder needed to be cleaned up and the cam needed to be fixed, the assembly took a little longer than usual. I was so lucky finding all the parts that fit together. Even the motor wires were just long enough to reach.

The quadcopter is feather weight with more than enough thrust and it’s controllable too. The FPV signal is strong and video quality is good. I’m really happy and I think it looks okay. That’s surprising as it is made of used parts from 8 different quads.

Basically it’s a 90mm FPV quadcopter with an F3 brushed flight controller and 8.5 mm motors that I didn’t know that I had.