Show Posts
Pages: 1 [2] 3 4 ... 93
16  Using Arduino / Motors, Mechanics, and Power / Re: Control two 5v stepper motors with single arduino board on: January 07, 2014, 12:58:38 pm
Good advice.  But it is possible with your board.
17  Using Arduino / Motors, Mechanics, and Power / Re: Build or buy Galvo for Laser mirrors? on: January 07, 2014, 12:56:17 pm
@jackrae- I tried pulsing my laser while the mirror is spinning.  At a slow RPM I cannot make a dot, but a line nearly 1 degree long.  With a shorter pulse the line is dim.  Any idea why?

Chan's tutorial sounds like the best solution for someone who has a lot of time on their hands.  Can anyone think of a shortcut?  Something to buy for cheap?  An experiment to try?  I wouldn't mind learning something along the way.
18  Using Arduino / Motors, Mechanics, and Power / Build or buy Galvo for Laser mirrors? on: January 07, 2014, 01:14:37 am
Was looking online for a way to control mirrors for a laser.  Closed loop feedback would be ideal, but I'd be willing to try no feedback like a speaker or meter movement.  How can I build something to experiment with?  Can I use a brushless R/C motor to move 5 degrees with many analog steps in between poles?  A linear actuator?  Hard drive linear motor?  Where can I find these or an old HDD?  I've tried a stepper but with gears it's not fast enough I'd like 1-2kpps.  Without gears it can move back and forth 1.8 degrees quickly, but not in between.  Any ideas to help me brainstorm?
19  Using Arduino / Motors, Mechanics, and Power / Re: 28BYJ-48 5-Volt Stepper on: January 07, 2014, 12:53:37 am
All that you said makes sense to me.  You can get 35RPM by using a higher voltage with these tiny motors!
20  Using Arduino / Project Guidance / Re: Detect interference from power lines on: January 02, 2014, 09:01:09 pm
How can I measure this field?
Ignoring the type of receiver used for a moment.
21  Using Arduino / Project Guidance / Re: Detect interference from power lines on: January 02, 2014, 05:09:30 pm
A cell phone transmitting conversation does not interfere with a modern 2.4ghz radio.
Not even inches from the receiver, while the transmitter is 0.38 miles away.
I have heard pilots say it interferes NEXT TO THE TRANSMITTER while flying!
22  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...
23  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?
24  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.
25  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...
26  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.
27  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? 
28  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. 
29  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?
30  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.
Pages: 1 [2] 3 4 ... 93