There are a few electrical requirements for our RobotRacing chassis:
1. Replace NiCAD batteries with LiION or LiPo batteries.
1a. Buy the appropriate battery charger.
2. Determine power requirements for on-board computer and buy extra batteries if necessary.
3. Make some power regulators (PCBs) for the sensors and embedded electronics.
4. Include a large red E-stop button for the motors.
5. Design a remote E-stop if there is time.
Rehman
Soren,
That comparison was great! XBee sounds like fun, but seems like overkill for just an on/off switch. If you just want to learn it, maybe you can expand the project to transmit more, like maybe some off-board monitoring, for debugging, etc.
For the E-Stop the most important thing is reliability. i.e. stick to what we know works. If a garage door opener and keyless entry use RF, maybe we can do something similar. Maybe that "General TX/RX" would work too.
I think you should just buy some stuff and start playing with it, then test it over and over for reliability. We can't afford to have this fail.
Does $50 sound like a reasonable budget for the complete E-Stop project?
Rehman
You're right and I quote, "For the E-Stop the most important thing is reliability..."
I realized that anything I build will not be as reliable as a commercial product, so I looked for off the shelf transmitters and receivers.
The nearby Canadian Tire has this receiver for $35:
http://www.canadiantire.ca/AST/browse/3/HouseHome/DoorAccessories/Garage...
and this compatible remote control for $30:
http://www.canadiantire.ca/AST/browse/3/HouseHome/DoorAccessories/Garage...
I think we can crack open the receiver and use it as a relay. The only problem might be the size of the receiver and how much power it draws!
Any comments?!
I like that idea, but I'm worried that it will run off of AC. Why don't you look for something that is already DC like this http://www.allelectronics.com/make-a-store/item/RC-13/4-CHANNEL-ON-/-OFF....
Cheers,
Rehman
The only thing that I didn't like about the one above was that I couldn't find any more info on it!
I found an alternative:
2 CHANNEL REMOTE RF RELAY BOARD & TRANSMITTER = $30
*Circuit draws 9mA in idle state, 1 relay energized 40mA and 2 relays energized draws 70mA.
*Receiver Power 12 VDC
http://www.electronickits.com/remote_control/rf2.htm
Which one should I buy?! I wanna order soon so it gets here by the end of April...
I think XBee (NOT ZigBee) is a good choice if I wanna build the E-STOP from scratch. There are all kinds of XBee tutorials available online(e.g. http://www.adafruit.com/blog/2009/04/21/using-xbees-to-control-relays).
Here is a comparison between some wireless options (scroll all the way down to comparison section and read the POINT-FORMs)
http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=128
There are also off-the-shelf kits (ranging $10 to $100!!!) like this for $40
http://www.robotshop.ca/seeedstudio-315mhz-4-ch-315mhz-wireless-relay-sw...
and this one is crazyyyy cheap!!!!! MADE-IN-CHINA
http://cgi.ebay.ca/Wireless-Switch-2CH-Momentary-Remote-Relay-Receiver_W...