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R/C Answered

Hi, I'm making plans for a remote control car from scratch, and have a few questions. Are hobby motors able to go backwards, how do you control that? Any ideas on making a wireless usb cord for a webcam? Do you know of any small things (like motors) that could move a switch remotely for the steering mechanism? Any other ideas?


Tamiya have a lot of excellent hobby sets... yesterday I was looking at the tank tread set, dual gearbox set and universal plate. Using those three compoenents you would have the chassis, drive mechanism and steering mechanism sorted. Total price was about $45 Australian. Then of course you've got the control side. By far the simplest and easiest solution would be to repurpose an existing RC transmitter/reciever. The easiest DIY solution I can come up with is a cheap 433MHz radio transmitter (sparkfun have them for $15-ish for the rx/tx pair) plus a microcontroller on each end, or on the reciever side only if you are willing to use your PC for input. Then again you may not want to go down the tracked vehicle path. Again the dual gearbox would be the a good basis for a rear wheel drive car. If you are using a microcontroller on the reciever side you could use a servo for front wheel steering.

I think that im just going to take apart an old car, link the forward/backward switch to the left motors, and link th right motors to the left/right switch. Becauase i'm going for alot of raw power, im using a motor for each wheel, and like i said before, will go forward on one side, and backwards on the other when i want to turn. If I do the webcam thing, ill get another and just hook a normal toggle switch instead of the one they have so that i can turn the light on/off

I may not even have a webcam if i cant figure a way to make a weireless usb cord, I jsut want a LOT of power and speed.

That looks pretty cool, but do they talk about how to setup a remote and receiver? Because thats [as far as i know] the only part im still fogged about.

go buy a cheap rc car and fit the inside parts to a cool model car

I wanted to do it more from scratch, not just changing the body. Im going to use 4 separate hobby motors, and do it all like that, though i may use a rc cars insides for the wireless part.

I was planning on making it totally from scratch..my plans were to have a motor for each wheel, and have the lefts controlled together and rights controlled together so i would have left go backward and right forward to urn left...I just need a wireless switch somehow.

there isn't really a easy way to make a wireless switch, the cheapest way to go is using a toy r/c car's electronics, if you want more power, then add a set of relays as a h-bridge my friend actually used a four relays, 4 transistors, a few resistors, and a zipzap car, and his scratch built r/c car set a record for our computer engineering class race track

That might be the easiest way, just to get one or two small cars, and rip out the electronics. How can one extend the range of those small ones?

i think all motors can go backwards, but you need a speed controller that can reverse how "scratch" do you want to go? if you get a r/c kit it could come with servos that you can use for steering

For DC motors or for brushless motors? there's a pretty good set of forums at http://www.rcgroups.com check out the forum on DIY electronics. Going from a simple forward-only speed control to a bi-directional one adds quite a bit of complexity (you go from one transistor to a minimum of 4), except that may not be how you want to handle it for a car (you want a reverse GEAR, which could be implemented with a relayor mechanics independently of the speed control.)

I was going to use a "hobby motor" from radio shack. ...all of a sudden this is seeming alot more complicated...

Yeah, it gets complicated pretty fast. You'll probably need a gearbox of some kind as well. There's a reason that a lot of robotics hobbyists tend to start with an off-the-shelf toy of some kind that has already put the mechanical bits together reasonably well (and probably in such huge quantities that the working toy is cheaper than bare parts bought by a DIY-er.) You shouldn't necessarily let THAT stop you. You can look at my 0Motor Speed Control Hack to get an idea how speed controllers work. (I wonder if I can add a "reverse" function without too much trouble... Hmm.)