Show Posts
Pages: 1 [2]
16  Using Arduino / Motors, Mechanics, and Power / Re: Simple motor question.. on: February 24, 2013, 12:45:20 am
Enrico, there is virtually no limit to what an arduino board can control, for instance, I have successfully controlled my milling machine spindles which has 2 by 2HP three phase electric motors on it! The trick is that the arduino board won't power these sorts of things directly (obviously), so you need to find something to interface with it, eg relays or in my case, a VFD (Variable Frequency Drive) which has a serial port interface. Also, when you get to these bigger items, you need to make sure your board is isolated from any feedback from these motors to protect your board and to ensure it functions properly.
17  Using Arduino / Motors, Mechanics, and Power / Re: Heater control on: February 23, 2013, 05:41:53 am
Hi mycrotrol, I would like to add that you should also do some research on optical isolation or similar as you will be needing to switch high voltage along with high amperage. Here in Australia it is not uncommon to have 240v AC at 25 amps supplying the heaters. Another thing is as you design the system, you should look at making it fail-safe. That is, if anything goes wrong anywhere, the main power is left OFF. Hot water heaters are potentially deadly items if not controlled properly. That is also why they have a water relief valve to release pressure (or release under high temp as well) to prevent explosion. I personally have seen a 250L heater level a brick wall as the owner " plugged the leak" on the TPR relief valve. Another thing to keep in mind is if you are planing to wash with or drink this water, you must keep the temp above 65 Celsius to prevent legionares disease among other things.
18  Using Arduino / Motors, Mechanics, and Power / Re: L293D Getting Really Hot, Really Fast on: February 23, 2013, 04:12:57 am
Another thing to remember is some driver boards come without heatsinks on the chips and they leave it up to you to fit them afterwards. With this in mind you'll find a driver board that can handle 25A may only handle 1-5A without the heatsinks installed. Some boards have them factory and I'm not sure why they supply others without
, maybe to save on cost?
19  Using Arduino / Motors, Mechanics, and Power / Re: Simple motor question.. on: February 23, 2013, 02:05:56 am
If you get into the nitty gritty, I believe there is a small difference in the load and current draw for each direction, but I have never had a problem and therefore never worried about researching why. There may also be a slight difference in each motor as well, even if they are the same model. The main issue you might have is getting the robot to track straight over a long distance. You can calibrate this with the code or, if you need to adjust it on the fly,via a trimpot on either the motors or for higher currents, run a trimpot into an analog input and use it as a reference to bias one motor or the other.
20  Using Arduino / Motors, Mechanics, and Power / Re: 30RPM Worm Drive on: February 23, 2013, 01:03:18 am
If you are in Australia, try Jaycar. they have some dc reduction motors and worm drive kits at reasonable prices. How much torque do you need?
21  Using Arduino / Motors, Mechanics, and Power / Re: Magneto interference with arduino on: February 23, 2013, 12:56:04 am
Thankyou, I shall, would you know if I would have to do it to the earth only or to all the inputs, the other inputs read the alternator so am I able to presume they are electrically isolated from the earth noise?
22  Using Arduino / Motors, Mechanics, and Power / Re: Simple motor question.. on: February 23, 2013, 12:51:27 am
There is no problem changing polarity on a permanent magnet motor so yes, you could just swap the wires, but couldn't you just do it in your code? I presume the motors will be bi-directional in the application anyway?
23  Using Arduino / Motors, Mechanics, and Power / Magneto interference with arduino on: February 23, 2013, 12:32:26 am
Hi guys, I'm trying to use a freetronics eleven (UNO) with a LCD screen shield on an alternator based generator I have built. The board will be used to read volts, amps and RPM of the 2HP two stroke motor.  It will also interface with the field coil on the alternator to control max load on motor as well as the voltage and current outputs. I believe all is well with the interface between the UNO and the alternator as I have reduced all the inputs to 4v via resistors to ground and the RPM input is taken from one of the three phases of the alternator winding before the bridge rectifier to avoid feedback from the motors magneto. 
The problem I have is the magneto on the motor is causing the LCD screen to read out some kind of ancient Egyptian language and the board eventually shuts down. The unit works perfectly if you remove the magneto from the motor and spin it all by hand so I'm led to believe this is not a code issue. I have used double shielded cable all round and mounted the boards in an aluminum enclosure to try and reduce noise. It seems now the interference is finding its way to the unit via the ground wire and I have no idea how to stop it as I need to have the arduino grounded to the generator as it is its power source.
Any help will be much appreciated but, if possible, try to dumb it down for me as I'm not a guru with this stuff (yet).
Pages: 1 [2]