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Philip
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My guess is that it would work. The brushed version has a 2 A output so, if they use the same speed controller, it will power ant weight motors. Or it might burn up.
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Post Sun Jul 20, 2014 9:30 am 
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Nick
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Almost $46 is expensive unless you really need the space saving. To convert the servos, you will also need to hack the feedback for continuous rotation.
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Post Sun Jul 20, 2014 9:40 am 
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Glen
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Heyo,

Can any electronics peoples let me know if i might expect any issues with this setup for my laser.

Background - i was planning to use the TTL high input to the laser power supply (5v from the arduino to fire the beam), TTL low for the test button and the master on switch to the water pump interlock (wont let the laser fire if it's open circuit)

Very annoyingly the interlock and TTL high both dont work. Only the TTL low. Until light object sends me a new one i've hacked this together. It works.



The arduino is set to have the output high normally and pulls low to fire the laser.

The test button and arduino should never be on at the same time. But it might happen if i lean on the machine or something Razz

The system is running 240v for the laser psu itself, 24v for the steppers and 5v for the arduino. They are all tied to the same ground. Reckon ill have any issues with ground loops or any such with so many voltage systems?
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Post Sun Aug 31, 2014 12:30 am 
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Tim



Joined: 30 Oct 2013
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Location: QLD


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Hey Glen,

Interested in this project so will follow thread Very Happy

I always keep AC ground and DC grounded devices separate, if it means
plugging a grounded AC device into a "safty switch" power board and then plugging in an old Laptop power supply, with a ground lead on the same power board, building a drop down voltage regulator in a box ( reg & a couple of caps ) on vero board that plugs into the laptop psu and feeding the Arduino 12volts from there.


quote:
Reckon ill have any issues with ground loops or any such with so many voltage systems?


I honestly don't know I just do what I wrote above because it works and is safe.

Cheers, Tim Very Happy

Post Sun Aug 31, 2014 9:32 pm 
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Nick
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If you run all the grounds to a single point (usually the earth point on the chassis), then you shouldn't have any loop problems - that's the way its done in audio gear to avoid hum pick-up.
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Post Sun Aug 31, 2014 10:45 pm 
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Valen
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Watch the run lengths on your wires and what they run near, TTL inputs are sensitive to noise and high voltages.

I'd look at putting something like a 10-100k R on the power input to the whole thing (top right), just to play it safe.

Some models of arduino are 3.3V too, ttl is usually 5V so it might be an idea to just check that too.
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Post Mon Sep 01, 2014 11:07 am 
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Glen
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Cool well i had more of a play with it and it turned out the laser would only fire at half power constantly under arduino control. Sorted out the grounding and it's good again Smile

Whats the reasoning behind a resistor to ground then? the arduino has its own current limiting resistor and thats about all that i thought could be damaged.

+ cheers Tim Smile Ill put up more updates to my laser build later when a bit mores been done Very Happy
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Post Tue Sep 02, 2014 12:16 pm 
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Valen
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you sure that a gpio on an arduino has a current limiting resistor by default?
Last I checked they had just standard I/O pins brought out.

TTL inputs are floating they have no inherent drive high or low and will often oscillate in response to radio noise. Pulling the line high or low will stop it from floating when its not driven.
Looking at your schematic again (i was out of it last night) you should have a pulldown resistor (like 100K) right on the input to the laser PSU so it gets pulled down when the "master switch" is open and that input would be floating. Your psu may already have something in it to do this in theory the manual should say if it has a pullup or down but yeah, Chinese manual.
Then put like a 200 ohm resistor on your power input line (so if you short something (wire rubs through to casing) it won't blow up).
The 1.5K R on the arduino will protect it and override the 100K on the pulldown.
I'd look at dropping that to like 1K or even 500 ohm if you are doing PWM on that line and its of any length, you would need to scope it to see if its got any issues really.

Your arduino and the laser PSU will need to share a ground as will whatever the source of power you have for the button there, Ideally you want to have your analog, digitial and high power grounds running in their own seperate areas, then bring them all back to one point. You want to do that without making a loop for the power as well ;->
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Post Tue Sep 02, 2014 1:10 pm 
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Jaemus
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I was also under the impression there's no current limiting resistor on Arduino outputs

At least with standard boards, I've only played with a China clone Duemilanove and a Freetronics Uno clone
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Post Sat Sep 06, 2014 7:58 pm 
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TIM88



Joined: 19 Sep 2014
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Hey guys long time no speak.

My old user name was TIMMEH havent been here for a while and i am wayyy behind on this stuff.

Anyway i have noticed a number of new motors and gearboxes mentioned.

I was going to buy 4X banebots p80 4:1 gearboxes but was wondering if anyone has some they want to sell or if they know of a stronger gearbox easily matched to the cim motor in the same price range?

Post Sat Sep 20, 2014 7:17 pm 
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timmeh
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Been doing allot of reading up on the ax2550 and the ldc1430 controllers.

Two ldc1430 controllers spec wise offer the same current output and limits as one ax2550 but they are cheaper and only weigh 200grams each yet the ax2550 is 1.5kg

The ax2550 has finned heatsink while the ldc1430 has a heat conductive base plate.

According to a Roboteq tech they should both perform the same.

Why would Roboteq still then be making those bulky blue boxes when they have these smaller versions which seem much neater lighter are less expensive?

I am thinking of switching out my ax2550 to 2x ldc1430 but i am trying to understand how or if they do really perform the same seing as tho they are so much smaller and compact.
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Post Tue Sep 23, 2014 9:06 am 
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Cpnwolfe



Joined: 29 May 2012
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how does everyone weigh their robots before the competition? last year I tried cheap analogue scales and they were way off.

this year I have been to the post office but I cannot do that everytime I change something, Bought a digital scale today at betta electrical ($50 weightwatcher one) but it still does not seem that accurate. and my little kitchen scale can only cope with 3KGs just interested to see whateveryone is using.

Post Sat Sep 27, 2014 5:20 pm 
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dyrodium
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I have a digital scale at home, I weigh myself, then weigh myself holding the robot and subtract the difference. Laughing Usually close enough, then again my bots are always like, 4 KG under. Rolling Eyes
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Post Sat Sep 27, 2014 5:22 pm 
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Glen
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hahaa, we have good ones at work i've been using, but the bathroom ones are off limits for me now. Weighed that flipper i made last year at 13.55kg and it was 14.something at the event. Dammit! Laughing
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Post Sat Sep 27, 2014 5:25 pm 
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seanet1310



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I typically just turn up and hope for the best but my bots are mostly plastic so can go on a diet in 30 seconds if need be.
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Post Sat Sep 27, 2014 5:38 pm 
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