Category Archives: Engineering

Club photography: Lighting experiment

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I was thinking about experimenting with a couple of flashes next time I go out club shooting. I do a lot of shooting at Club Neutral here in Toronto, and I thought I ‘d start my experiments there, since I know the layout of the place.

Above the dance floor, there is a frame that is attached to the ceiling which holds all the lights. I can easily reach this frame (ceiling is low at Neutral) I am going to attach 2 flash units to the frame. One at the front pointing away from the stage (towards the DJ booth at the back), and one at 90deg to the first strobe. And point them to illuminate the crowds.

Both flashes will always go off together, and what I’m hoping to accomplish is to always have light available when photographing crowd members dancing. Having 2 light sources at 90deg to each other should (emphasis on should) ensure that my subjects will always at least have side lighting.

Now this will light up the entire club, so all the people will be lit up. To try to isolate just one person dancing, I will shoot from down low. This should ensure that I only capture the person dancing with minimal heads in the background.

I’ve made some clamps (and will also buy a proper one) to clamp the flash to the existing structure at the club.

Will add to this once this experiment is complete.

Lumber cost

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Just came back from visiting my local Home Depot in Etobicoke (Canada) at Shareway Mall.

I’ve been wanting to design a deck, and a picnic table, but didn’t know how much it would cost me. Now I should be able to estimate a cost without making a trip to HD.
Here are the current prices as of 18 April 2010.

Pressure Treated Lumber:

5/4 x 6 x 16 – $10.76

4 x 4 x 12 – $14

2 x 4 x 10 – $5.75

2 x 8 x 12 – $14

2 x 6 x 12 – $10.30

1 x 6 x 8 – $3.55

Heli/RC parts and info

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Info:

TREX 450 bible

Parts:

HK-Parts

Hobby King

HobbyHobby (Mississauga location)

RC711

HeliDirect

Hobby-USA (carries CopterX Black Angel parts)

HeliPal

Value Hobby (in USA)

AC-RC

Blades:

Airy Harden Blade II : Highly cambered blades that come in 238mm, 210mm, 185mm and 160mm.
The HoneyBee CP2 (that uses the 238mm blades) has a rotor speed of 17oorpm. So keep things under 2000prm. (Reference)

Supposedly, more surface area and more camber on these smaller blades for a Blade CX2/Lama V4.

Pinions:

Heli-Direct Pinions selection: well organized

Calculate RC Helicopter Head Speed

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In order to calculate your RC helicopter head speed, there are 4 things you need to know:

  1. The number of Teeth (T) of your motor pinion. If you set up your RC helicopter yourself, you should know that by heart. If you bought the RC Helicopter RTF (ready to fly) or someone set it up for you, just count the teeth of your motor pinion. It is a lot easier than counting the teeth of your main gear.
  2. The number of T of the main gear. This is easy to find – just count the teeth on your main gear. Well, not that easy – just try it, you’ll know what I mean. I get a different number every time I count it. Again, you may find the number of your main gear T on the owner manual.
  3. Motor kv – the rpm (head Speed) produced by a motor per volt applied. You should be able to get the motor kv from the motor specification sheet.
  4. Voltage: This is the voltage of your battery. You may get this information from your battery specification sheet or label.
  5. Efficiency rate: This is the percentage of your RC helicopter motor efficiency when you are flying with your set up. It is the norm to use 80% (.8) or 90% (.9) depending many factors though you run 100% on your throttle curve.

As it was said earlier, the result would only give you a rough estimate of the head speed. A better way is to use a tachometer to measure your RC Helicopter head speed.

Estimate Head Speed = (Motor kv * Battery Voltage /(Main Gear /Teeth of Pinion)) * Efficiency Rate

Quadrotor

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Going to put together a list of what I would need to build a quad rotor that can do some lifting. Quad built using motors on each corner.

Inspired by the stability of this quad. Video showing AP stability shown here.

LED Strips from HK to light the 4 corners.

Motors (listed in this post) Turnigy 2209. Going with this 20L-22 motor

Turnigy 18A speed controller from HK.

3.5mm plugs from HK

Body:
HK450 heli tail booms. Carbon Fiber ones, and Aluminum ones.

Boom holder.

Battery.

Props. Get them here?

Some more details.

Tricopter controller

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I’ve decided to use William’s tricopter controller boards for my own copter.

Reasons being that I’m using 3 rotors, and that the code is written in basic, so that will be easy for me to edit.
I don’t plan on starting with the full IMU cube. Just 2 gyros will do for a start, and I will add on later. Probably a bad idea not to use the whole cube… should just bite the bullet, and make my life simpler, since the development of this copter is secondary to the platform I am after.

Also Will’s code will not dirrectly work on my machine, since I will be adjusting the pitch on the 3 corners, not the motor speed. And the servo that he controlls, will be used by me to control the main motor speed.
These modifications will be made to the code when I get to that stage.