Show Posts
Pages: 1 2 [3] 4 5 ... 93
31  Using Arduino / Project Guidance / Re: Detect interference from power lines on: January 02, 2014, 05:02:22 pm
I agree!  I have found no noise from 30-1000Mhz.  Yet R/C forums have 100's of users who insist they lost their plane because of interference.  Few disagree on those forums.  I saw a legal case that was decided on our side.  Just back from a range test.  I am using a cheap 2.4Ghz Chinese radio walking along the path under the lines.  We walked for miles staying apart.  It works reliably at 0.38 miles.  I have moved both the transmitter and receiver when I could so they are still line of sight.  There were no glitches.  At this distance trees or metal in the way prevent reception.  There is no way to get this distance here, on the ground, without a valley between hilltops.  Kansas or an ocean would work.  It is interesting that I have been unable to get the same range in the past, with a different radio, without power lines.  Then line of sight range was limited even when space was available to move further apart.  I will have to try this radio when I find a clearing large enough.  It appears that the power lines INCREASE distance and reliability.  Is that possible?  The only glitches were from thick trees or metal towers in the way.  What's the maximum range you have gotten with any R/C equipment new or old?  Is there a better way to measure interference?

I have gotten 2 miles with a 1W transmitter and 16 element Yagi from a mountaintop...
32  Using Arduino / Project Guidance / Re: Detect interference from power lines on: January 02, 2014, 04:18:48 pm
There's nothing scary about climbing a tower, except for the height.  In this case my toy helicopter was near the lines without any apparent interference.  There is little evidence that working 10m from 110kv lines causes cancer day after day.  How do you recognize a transformer from far away on the ground?  It seems that there are none nearby.  I imagine there are many faults effecting R/C control.  Can there be any involving wires only?
33  Using Arduino / Project Guidance / Re: first project : DSLR trigger on: January 02, 2014, 01:48:41 pm
I agree both must be pressed, and focusing considered.  There is no need for optocouplers, as long as there is no high voltage source in your project.
34  Using Arduino / Project Guidance / Detect interference from power lines on: January 02, 2014, 01:46:33 pm
I've built a device to detect interference in the AM band.  With this it is possible to measure the distance from a 110kv power line.  Is this same noise responsible for failure of a 2.4ghz digital transmission?  How can I measure it?  Does it correlate with the xKhz noise?  I've experimented by raising a receiving antenna to be very close to power lines.  No degradation was noticeable.  I have heard both sides, that it predictably and repeatably effects reception, and that it doesn't at all above 2ghz.  I am using a SDR to measure the noise change in various bands 20m from 110kv power lines.  So far I see nothing above 20Mhz.  Maybe a faulty transformer is responsible for all documented cases of R/C failure above 2ghz?  In many cases this has been proven.  Would an nrf24l01 be sensitive enough to measure any potential problems?  I have no way to determine this since I don't have a problem 10m from the 110kv lines...
35  Using Arduino / Project Guidance / Re: Arduino BLE presence detector on: January 02, 2014, 01:32:47 pm
Would be a great project!  I hope someone has an answer here.  It could be done with NRF24l01 hardware.
36  Community / Exhibition / Gallery / Re: Laser Lissajous with Audio Sync using Arduino (clone) and Python on: January 02, 2014, 11:24:07 am
I did something similar in 1985 using DC motors and PLL to control the phase between the 2 motors so the spirograph image will remain stable.  How can I do this today using stepper motors?  It would be jerky? 
37  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: January 02, 2014, 10:52:28 am
You can also measure how long it takes to get a reply.  With retranmission you will get 3 values, immediate, delayed, or sometimes none.  How often you get none is useful. 
38  Using Arduino / Motors, Mechanics, and Power / Re: Can a DC motor hold up a weight? on: January 02, 2014, 10:44:27 am
It is good!  A normally closed relay would be best because the switch only needs to be open for a short time while moving.  The coil current is significant when battery powered compared to an Arduino.  Have you figured out how to make it sleep?
39  Using Arduino / Project Guidance / Re: first project : DSLR trigger on: January 02, 2014, 10:37:38 am
Do not be afraid to connect the Uno pin directly to the camera plug.  It works perfectly and simply for your model.  Use a 1-10k resistor just in case I'm wrong.  If you don't trust me.
40  Using Arduino / Project Guidance / Re: arduino uno sleep mode?? on: January 02, 2014, 10:33:34 am
I like this because it is simple:

The microcontroller uses almost no current compared to the supporting circuit.  Turn off the USB chip and LED.  Now you're left with the regulator idle current.
41  Using Arduino / Project Guidance / Re: Forty-two Unos in a row on: January 02, 2014, 10:30:44 am
Only one wire is needed for the entire length.  How about a really slow PWM.  Like count how long the pin is high every 30 seconds.  This would allow 31 values 0-30.  Why limit this to integers?
42  Community / Gigs and Collaborations / Re: looking for experienced code writer for joint work in movie replica creations. on: January 02, 2014, 10:21:41 am
I have written Arduino code to read a script to automate motion for the movie industry.  The same script format can drive multiple servos and cheap steppers at the same time with one microcontroller.  I do not have an easy way to generate the scripts.  If you can understand how to do this, the rest is easy.  A new idea is to use a special servo with feedback to generate the scripts by moving the unit by hand.  This will take some development effort buy maybe this is what you want?
43  Using Arduino / Motors, Mechanics, and Power / Re: Can a DC motor hold up a weight? on: January 02, 2014, 10:11:59 am
A 28byj-48 stepper motor can support a large weight without power because of the 64:1 gearbox.  Look on Ebay it is only $2.  Your challenge is to get enough torque to lift 2kg.  There are 2 methods.  Use 20v to drive a 5v motor.  Leave plenty of time for cooling.  Or use a small shaft as a drum to wind the string.  Have you seen my code to do this?
44  Using Arduino / Motors, Mechanics, and Power / Re: 28BYJ-48 5-Volt Stepper on: January 02, 2014, 09:52:38 am
There must be a problem or misunderstanding in the code.  Off the top of my head I have seen 30RPM.  At 20RPM for example the speed is almost infinitely variable.  Each step can be 800us or 801us.  So you can go 20.02 or 20.04RPM. 

We can conclude that most motors are and not 4096.
45  Community / Bar Sport / Re: off planet robot wars! on: December 29, 2013, 01:46:17 pm
We are considering it for the entertainment value alone!
Pages: 1 2 [3] 4 5 ... 93