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1  Forum 2005-2010 (read only) / Development / Starting a new robotic project! on: January 05, 2007, 06:50:34 am
EDIT: Found a more appropriate place for this, I think. Here ->
2  Forum 2005-2010 (read only) / Interfacing / Re: Arduino PWM on: February 17, 2007, 10:29:47 pm
In case anyone was wondering, I managed to make it a two-speed trike using the following:
(I only had 2 30 amp relays, a couple of switches, and a bit of wiring handy, so I came up with this design)
3  Forum 2005-2010 (read only) / Interfacing / Re: Arduino PWM on: February 10, 2007, 03:44:21 am
Ok I suppose the problem with my design is that little or no transistors have NC/NO? Which is why I need 4 of them?

I suppose all of these transistors in the first diagram are capable of being driven directly from the arduino PWM outputs?
4  Forum 2005-2010 (read only) / Interfacing / Re: Arduino PWM on: February 10, 2007, 03:31:11 am
Thanks for the information everyone, and sorry to be posting a month later - haven't had time for this lately.

Ok, I haven't yet got an arduino (Still!), but am trying to look at my options here. I could get an arduino for $31.95 USD ~$40 AUD
from here:
Plus postage. Next I need something to interpret the PWM signal - that circuit above looks good, but I am hardly any good at complicated looking circuits!

Here's a simple HBridge which I just drew in MSPaint. Why couldn't I just use that? Its perfect! By default, the brake is on. When you turn on Relay2, it goes backwards, when you turn on relay 1, it goes forwards.

The question is, what part do I need to interpret an analogue signal (from a potentiometer) and put that into PWM, and then according to the PWM, switch these relays on and off very fast!
5  Forum 2005-2010 (read only) / Interfacing / Arduino PWM on: January 11, 2007, 08:24:23 am
Ok, Firstly I just need to clarify PWM. As I understand it, Pulse Width Modulation is turning things on and off at very high speeds in order to see an average effect.

I'd like to control a high-current DC electric motor and am wondering how I should do it.

Basically, I have a "Golf Trike" which I got at an auction. It is a 3-wheeled contraption and the back wheel drives it. It has 3 12v batteries in series to provide 36v.

At its peak, the electric motor can suck 750w - that's 20.8 amps! (At 36v).

Here are the problems
1) I still dont know much about the arduino.
2) How do I control the speed of an electric motor from the arduino?

Do I need a solid state relay that can switch it on and off very fast? This sounds like a bad idea.

Help! :s

(P.S The reason it doesn't work already is because the cheap chinese design (The entire circuit was covered in glue overheated when a "large" friend of mine was on it for a couple of hours). So I would need something which exceeds the requirements so that it doesn't burn out.)

It has an accelerator but I dont know how that works. I'm sure it would be compatible with the arduino. But is the arduino what I want for this project?
6  Forum 2005-2010 (read only) / Interfacing / Re: Checking Voltage on: January 06, 2007, 05:01:30 pm
I've just found this image:

See, it can only be between house & mains, or house & generator - NEVER generator & mains.

It would be a proper transfer switch! All this will do is automate switching it on and off! - That has to be safe smiley-razz P.S: Generator is only 6000kVA.
7  Forum 2005-2010 (read only) / Interfacing / Re: Checking Voltage on: January 06, 2007, 05:38:22 am
Heh. I'm sure changeover switches aren't that expensive! All they are is a double-throw switch!

At any rate, I'll investigate it further and post my findings and if I go ahead with it.
8  Forum 2005-2010 (read only) / Interfacing / Re: Checking Voltage on: January 05, 2007, 08:21:46 am
Which is why I just wanted an electrician to install a regular changeover switch, which I can plug some kind of mechanical level straight onto = Safe, and insurance-friendly!
9  Forum 2005-2010 (read only) / Interfacing / Re: Checking Voltage on: January 05, 2007, 07:51:57 am
I've been searching around, but anything for "automatic change over switch" brings up a whole device, including the computer to change it over :s
10  Forum 2005-2010 (read only) / Interfacing / Re: Checking Voltage on: January 05, 2007, 06:52:23 am
I haven't got the changeover switch yet - I didn't think it would be so big, and I thought solenoids had alot of power. Apparently not? Perhaps a small DC motor would be better instead!
11  Forum 2005-2010 (read only) / Interfacing / Checking Voltage on: January 05, 2007, 06:27:36 am
First of all, I'm almost completely an electronics n00b. My knowledge goes as far as connecting an LED or small DC motor to a battery :-)

I'm very interested in buying either a basic stamp or arduino. Apparently the arduino is better (and cheaper smiley-grin) so I think I will go with that, but I am unsure if it can do what I want it to!

I'd like to create an automatic changeover switch for my house & generator.

I would get a regular changeover switch installed, and somehow mount a solenoid onto it. That way, I'm not dealing with mains power directly.

I understand that I would need a relay connected to the arduino in order to control a solenoid. I would run the arduino off a 12v battery, constantly hooked up to a charger, so that gives me the power for the arduino, and 12v for things (like relays & solenoids) for when the power is off.

I dont know how much power a solenoid draws, but would a 5v solid state relay connected to an Output, and the ground on the arduino be able to turn a solenoid on and off using things like digitalWrite(pin, 1)?

Or would I need a 5v solid state relay to turn on another (solid state, or mechanical) relay to control the solenoid?

(Reason for this method is because I am not comfortable with making my own relays that have protection etc).

Also, I would need a fairly decent relay to start the generator... Hmm actually I could rip apart the key wiring and just use that. So would I need just two 5v solid state relays, or something else, is the question. smiley-razz

That is one side of it,
the other is: How should I check that there power - on the mains and on the generator.

I suppose I will need a power point on the other side of the changeover switch which is stepped down to 5v to plug into the arduino, so that it can tell when the power is back on.

And also one on the generator to tell that it is started and producing electricity.

How would this connect to the arduino though? Where would the + and - of the 5v go on the arduino? I cant connect them both to input pins. But I dont want and power to go into the arduino that might hurt it!

So, anyone up for helping a complete n00b out? smiley-grin

I also have another project I want to try, but I'll leave that to another thread smiley-grin
12  Forum 2005-2010 (read only) / Exhibition / Re: Poor man's 32 channel light controller on: February 11, 2008, 05:20:51 pm
Hmmm, for just lights, arduino would be overkill, wouldn't it? I was looking at doing a computer controlled light display last year and saw that you only need some basic kind of PIC to interpret the signals, when networked.

(However you're doing other things like microphone input - that will be interesting)
13  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Automating Gates/Garage Opening on: July 25, 2009, 11:39:39 pm
Perfect! I forgot all about active RFID. Perfect.

I will start researching this now!
14  Forum 2005-2010 (read only) / Frequently-Asked Questions / Automating Gates/Garage Opening on: July 24, 2009, 09:34:16 am
So apparently I'm too lazy to push the button on the remote!.

We have two separate electronic gates and a garage, all controlled by a remote control with 4 buttons.

My idea is to have an Arduino which will close the circuits on these buttons in response to various events, eg Car approaching gate or Car approaching garage.

I'm unsure what I can use to identify vehicle. Maybe I don't know how I should do it yet either. Perhaps an arduino with a GPS module could signal to open the gate when the car is approaching the zone that the gates are in, and close it when the car is leaving the zone. The Open/Close on a single button poses the problem that it might get out of sync.

I'd be interested to hear ideas - I will do some more thinking and come back to this thread later in the weekend.
15  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Creating a lawn mowing robot on: August 10, 2008, 03:51:50 am
Hrm, the next problem would be data storage. Maybe mapping = bad idea. I don't like the idea of a "stupid" robot roaming around mowing places twice though. Perhaps I can connect it to a PC (or more likely, a motherboard with a flash memory card) and have a program do the hard word while arduino just gathers data from the sensors... then I wonder - why wouldn't I connect the sensors directly into the PC's parallel port in the first place.

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