Balsa+me=no bueno

[andrewwski]

My entire EV cost me less than $50 and is capable of getting scores of 196+ consistently (not sure what my competition score was, but it was 2nd place at regionals, behind a team that was 198 or 199 something).

[dudeincolorado]

what did you use?

[andrewwski]

A timer-relay circuit.

There's three basic designs that seem to be popular and successful with EV...microcontrollers, timer-relay circuits, and wingnut brakes with limit switches (think Scrambler).

[gh]

The Electric Vehicle Wiki says "The motor is turned on for an adjustable amount of time and then stopped" about the timer method. This is dependent on a the vehicle taking a constant amount of time to travel a certain distance, which relies on the motor being supplied a certain voltage (assuming a regular brushed DC motor). To do that, you'd have to do your testing with only fresh batteries (or batteries of a given state of charge, I guess, but that's pretty hard to measure) or with a voltage regulator:

Electric_Vehicle#Voltage_Regulation

It's really not accurate to call a braking system "microcontrollers," since it's really the shaft encoder (or other sensor) that really makes it tick. You can do a timer with a microcontroller more easily than with a timer circuit, since all the timing circuitry is inside already. The idea behind the design is really using a sensor to detect how far the vehicle has traveled and stopping. To do that, you do need something to count with, which is where the microcontroller comes in.

[rocketman1555]

i know that one of my friend modified a vex system so that he could press a button for meters, another for decimeters, one for centimeters, and one for millimeters, it got first at state, but i don't know exactly how he did it, i think he used some programming

[gh]

Back on topic about jigs:


That's what I did to mass manufacture frames. I put a piece of cardboard cut out to the right shape on glass. It holds up the ribs as I glue, but there are cutout at the joints so that the cardboard doesn't get glued to it. The glass is nice, but dulls your knives VERY quickly.

Max Zaluska uses foam sandwich board (I think) to make really awesome jigs/template things:

[carneyf1d]

i think max uses styrene foam. but for science olympiad and making square frames, i never found the need to make a template. whatever works though.

[andrewwski]

Yeah...I used jigs like that quite a bit. Works well.

[dudeincolorado]

oh ok i get it seems useful

[geeks]

Could you tell us where we could get some information on designing our eggo-naut?
thanks !