Robo-Cross B

[darkwinters]

Hey all,

The latest vex controllers use a 75.0 mHz frequency. The Robo-Cross rules on the website state:

• Radio waves as allowed by FCC regulations, which correspond to both the
frequency (e.g. 2.4 GHz, 5.8 GHz, etc.) and the power (e.g. 100mW, 50mW, etc.).
Allowable examples include, but aren’t limited to: Bluetooth, WiFi, ZigBee, R/C
cars, etc.

• Note that some older R/C systems designed explicitly for model aircraft operate in
the 72.0 – 73.0 MHz range and are explicitly prohibited from operating model
‘surface’ vehicles and devices. The corresponding, allowable, surface devices
operate in the 75.4 – 76.0 MHz and 27 MHz range. Most modern R/C systems
operate in the 2.4 or 5.8 GHz range and incorporate ‘spread spectrum’
technology

Would the latest VEX frequency still be allowed?

[chalker]

Can you point to a link that shows the specs for Vex controllers at 75.0 MHz? According to this link, they are all in the allowable range: http://www.vexrobotics.com/75mhz-crystals.html

[darkwinters]

Can you point to a link that shows the specs for Vex controllers at 75.0 MHz? According to this link, they are all in the allowable range: http://www.vexrobotics.com/75mhz-crystals.html

Whoops - my bad.

From this page (http://www.vexrobotics.com/vex/products ... -2192.html), I had gotten the impression that the transmitter was to operate exactly at 75 mhz.

Thanks!

[Dr_Donut]

Does anyone have any good starter kits besides VEX? I heard they are a little pricy.

[1nxtmonster]

Does anyone have any good starter kits besides VEX? I heard they are a little pricy.

I would imagine that you could get along fine with a Lego Mindstorms. The EV3 has 4 motor ports (correct me if I'm wrong) and comes with a remote control. The precision won't be the best however.

[retired1]

Other than a tether rig I think that the cheapest decent equipment is a Vex pic v5 transmitter and rx. You can frequently find these on ebay for $40 to $50 including freight. You can buy a signal splitter and run up to 6 things off of it. The proper motor does not come up very often, same for solenoids--except at near list price. I do not remember if it takes the 2 wire or the 3 wire motor. One of the two takes a motor control per motor. Figure $30 for the splitter and something like that for the motor with the control.
This is a fraction or the top of the line Vex and can be fully functional. If need be, you can add another rig to it as long as it is on a different frequency and be able to control 12 items.

[jander14indoor]

I don't know about kit, but to get started, any RC vehicle chassis, treaded or rough terrain better, can be modified with simple attachments to make a cheap, effective robot. I saw one with a straight OWI robot arm attached to the top that did very well last year.

I'd suggest getting SOMETHING running fast to practice, develop ideas, find out what works and what doesn't is better than starting with the idea to build one perfect robot.

Jeff Anderson
Livonia, MI

[Robo-cross]

I have the vex clawbot kit and I built it and it is 32-33 cm wide.
Does anyone have ideas on how to make it smaller?

[Unome]

I have the vex clawbot kit and I built it and it is 32-33 cm wide.
Does anyone have ideas on how to make it smaller?

What is it made of? (your school probably (maybe) has something to cut metal & plastic with)

[Robo-cross]

It's metal