Radio Controlled Cars

Radio Controlled Car Article Snippets:

An RC kite is pretty much what it sounds like. That is, a kite-like aircraft fitted with RC (radio control) receiver and pulled through the air with a propeller. In structure, it has a lot in common with kites and yet it is flown around like an RC plane. The man behind the concept is Mr Michael Lim from Singapore. Mr Lim was formerly a jewelry designer but now finds it hard to drag himself away from further research and development of these amazing little flying machines!
Singapore is a crowded city-state-island in South-East Asia, with an enthusiastic and growing crowd of RC kite fliers. In typical Singapore fashion, the scene is very organized with simulator training, a ranking system for fliers and scheduled events.
So what exactly can a radio controlled kite do? It can…
float around like a glider, with the motor idling
perform all the basic aerobatic maneuvers like a light aircraft
‘hang on the prop’ in hovering or very slow flight, nose high in the air
zip around pylons like the Red Bull racers
I should add, only a well-trained pilot can do all the above!
The Best RC Kites Are Made In Singapore
That’s right, …

Radio Controlled Car Questions & Answers:

How do I make a circuit in which I can control the voltage by remote control?
I am trying to make a radio-controlled car, which can have variable speeds. For that, I want to control the voltage supplied to the car motor to be variable. I want it such that when I press a switch on the remote, the car increases the speed, while, if I press another switch, the car decreases the speed. I want the speed to be covered in 3-5 steps

I take it that the RC transmitter and receiver that you are using does not have a servo channel (continuously variable), you just have two on/off channels.
To get the control voltage you could use a digital up/down counter chip followed by a digital to analog converter. The up and down clock inputs would be connected to the 2 channel outputs. If you use a 4-bit chip, that will give you 16 speed steps, including stop.
Another way would be to use an op-amp configured as an integrator. One digital signal would cause it to ramp up, and the other to ramp down.
Once you have your control voltage you need to use it to control the motor speed. The easy way is to control the voltage across the motor using a transistor wired as an emitter-follower. That would be simple but inefficient. The best way would be to use a voltage controlled pulse-width modulating speed control circuit. You should find circuits for those on the net, try googling “model pulse width speed control”.