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Author Topic: Something That Flies  (Read 2085 times)

Agent_of_Change

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Something That Flies
« on: August 06, 2016, 02:22:32 PM »
So far, this is just 'a setup' for four motors with propellers. the end goal is a quadcopter, but currently it just needs to get off the ground.

i'm pretty sure there's at least one thing wrong with this...
« Last Edit: August 06, 2016, 03:20:37 PM by Agent_of_Change »

mogul

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Re: Something That Flies
« Reply #1 on: August 09, 2016, 02:17:56 AM »
i'm pretty sure there's at least one thing wrong with this...

I see plenty unusual ideas in this design. Not that this alone would indicate a problem.

Where i see the biggest challenge with what you have drawn so far is the power source. Assuming the two "9V" boxes are the usual 9V alkaline smoke alarm batteries, my experience is that they do not offer a great deal of power compared to their weight. 

Agent_of_Change

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Re: Something That Flies
« Reply #2 on: August 17, 2016, 04:14:53 PM »
Update:
I got my motors from old CD drives and I knew nothing about their specs. I just checked their current draw, and out of four, two draw 0.7A each and two draw 0.9A each. That's a tad inconvenient.

I should really have mentioned before that I don't know what I'm doing, and I'm only just finding out now about stuff like batteries having a maximum current.

Going forward at the advice of various peeps, especially mogul, I'm hoping to borrow a stationary power source and see what I can make happen with that. In the meantime, here's a newer drawing. I don't know the 'correct' way to do it, but I hope this is better.

20160817_231009.jpg
*20160817_231009.jpg (51.59 kB . 1024x576 - viewed 122 times)

G'Night yall.

bdk6

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Re: Something That Flies -- Schematic diagrams
« Reply #3 on: August 17, 2016, 04:44:42 PM »
A proper schematic diagram helps immensely with clarity of your circuit.  Schematics are the universal language of electronics.  I highly recommend you learn how to read and draw them, especially since you are going to have to learn it in school anyway.  Here's a decent introduction https://learn.sparkfun.com/tutorials/how-to-read-a-schematic

There are a LOT of computer tools for drawing schematics.  A few popular ones are Eagle, KiCad, and gEDA.  All of these also allow you to export the schematic directly to a PCB program if you decide to make a PCB.  If you do make a PCB and don't use a tool like that to help avoid errors, you are wasting your time. 

In any case, pick a program and learn how to create proper schematics.  These all have free versions.

KiCad http://kicad-pcb.org/
gEDA http://www.geda-project.org/
 Eagle https://cadsoft.io/.
« Last Edit: August 17, 2016, 04:54:44 PM by bdk6 »

bdk6

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Re: Something That Flies Motor current
« Reply #4 on: August 17, 2016, 04:57:31 PM »
One thing to note about motor current.  It will vary depending on the load on the motor.  With the motor not actually trying to move anything, it will draw minimum current.  The harder it has to work to move something (a vehicle, your hand, air, whatever) the more power it will draw.  It is important to know and accommodate the MAXIMUM current it can draw.

Agent_of_Change

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Re: Something That Flies
« Reply #5 on: August 18, 2016, 08:42:27 AM »
I don't know what happened, but my previous attempt to post this seems to have disappeared.
Long story short, I got ahold of a stationary power supply (im calling it an sps) and after only 3 hours (with bdk's help) I got things to work. Nothing flew, and one of the motors was dead, probably from soldering too slowly, but things worked at 7v (not the planned 9v) without getting warm. I took a photo and video.

20160818_143416[2].jpg
*20160818_143416[2].jpg (47.25 kB . 1024x576 - viewed 117 times)


The video came out better than expected, but admittedly I had to continuously fiddle with the blob of jumper cables, so most of the video doesn't have all three turning simultaneously. I'm still really happy about this, because power problems aren't such an issue now that I have access to an sps, and because something has been built for the first time in months, and because of the community feeling that came with this.

Going forward, I suppose there need to be new motors, controllers, and reversed propellers. That could take a while because of procrastination. The schematic diagramming is the more immediate thing. I've already been introduced to some of the symbols, I just didn't think to connect classroom diagrams with real life hobby stuff. If/when I draw things properly, iA I'll put it below.
« Last Edit: August 18, 2016, 12:41:18 PM by Agent_of_Change »

Bajdi

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Re: Something That Flies
« Reply #6 on: August 18, 2016, 09:47:42 AM »
Why are you using an L293 to control the motors? You only need to spin the motors in 1 direction so no H bridge is needed. The L293 is very old technology and has a big voltage drop (wasted power). Get yourself some logic level mosfets to control the motors. Much simpler and effective :)

mogul

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Re: Something That Flies
« Reply #7 on: August 18, 2016, 03:18:10 PM »
... Nothing flew ... I took a photo and video.

Really nice progress you make here. Now. lets see how much lift you actually made. Put the build on a kitchen scale and see how much it reduces it's weight when motors are at full speed.

And I second what Bajdi said, leave the H-bridges behind and get some cheap power MOSFET's. Logic level is good, and low on resistance is good too. I'm not a MOSFET expert, I usually get my parts directly from china on aliexpress.com, dirt cheap. Recently I got 5pcs FQP30N06L for about $1.70, including shipping. Others here will probably tell me why these are some lame devices - i usually forget to look on the most important parameter in the datasheet. Yes you know who you are, I'm looking at you...

Anyway, to show you how cheap it can be done: http://www.aliexpress.com/item/5PCS-FQP30N06-TO220-FQP30N06L-TO-220-30N06-free-shipping/32712777386.html

 

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