I need a critical help in designing a magic toy

[salvazero]

I want design this project for magic shows, and I would like to include this in the act.
How Can I design a circuit so I can make the ball move? I need to design circuit for it.

The wand will have the transmitter.
The ball will have the receiver in it.
I want to make it stop when the wand is less than 1 feet away and or plus 2+ feet away.
Start at 1-2 feet, spacing is not critical. Close is good enough. Parts I think I need.

The Wand
1. An adjustable transmitter
2. Battery The ball
1. A receiver
2. Motor-do not include in your circuit
3. Battery
4. Gears- do not include in your circuit

I need for you to advise me on what is the best way to make this magic toy. I just need the circuit without the motor or gears.
See the example


This is an example only

I need a correct circuit for it.

1. I need a transmitter to transmitter only at a distant of 1-2 feet only. I was told that I would need an adjustable transmitter and Receiver.
2. I will be removing the on and off switch in the ball and replacing it with the receiver, to tell it to come on or off. The receiver will open and close the circuit for the battery to activate the switch.

Can you supply me a schematic showing me the wires to connect and what type of transmitter and Receiver to buy and any other components that I might need to complete the circuit?
I want to know Schematic showing me the wires to connect and Parts I will need.




Any help will be appreciated.

Thanks in advance

 

[betwixt]

Is there any particular reason why you show the HT12 devices? They are data encoders and decoder and decoder ICs but it seems you only want a proximity detector.

From an electronic point of view, this is quite hard to do. Building a transmitter inside the wand should be easy enough but you need a fairly precise distance detection at the ball and that excludes the use of any directional antenna inside it. The trouble is, all antennae are directional and over such short distances, other factors such as the table material and nearby reflective surfaces will play a large part in the range it works over. Just using signal strength to assess the distance will not work reliably, especially as the receiver will be rotatating.

There are several solutions but I feel a radio link may be unsuitable due to it's unpredictability. Some ideas:

1. most relaible will be to ignore the distance sensing and manually 'drive' the ball by operating a covert switch, maybe squeezing the wand or pressing a hidden button.
2. push the ball magnetically.
3. use a low frequency, low intensity magnetic field and pick-up coil, this may suffer problems with directivity again.
4. if the ball material is suitable, use an invisible (IR for example) light source and sensor.

Just ideas....

Brian.

 

[salvazero]

Thank you very much Brian, for your time and consideration.

The drawings was just an example. I need to make it activate with an RF signal 1- 3 feet away.
Accuracy is not important, just as long as it operates when the device is near it.
I dont mind the size of the wand, I can work around that, I can put the transmitter under the magician's sleeve.

Is that possible?

 

[BradtheRad]

Consider broadcasting two different signals on different frequencies. One is strong, the other weak. The weak signal is only detected at less than 1 foot distance.

Also consider ultrasonic ranging between the ball and wand. (a) The ball sends out 'tick' sounds. (b) The wand hears it and sends back its own tick sound. (c) The ball waits until it detects the wand is between 1 & 3 feet away (1-3 milliSeconds), and changes its behavior.

Or, the wand sends out tics which are echoed back by the ball. The wand detects the ball at the desired distance, and sends commands via ultrasound.

The project is no doubt easier to construct if the ticks are in the audible range. This could still impress the audience as they hear the tics like a 'conversation' taking place between the ball and wand. It might enhance the effect. But then I'm not a showman, and instead it might tip them off to how the trick is done. So use your own judgment.

- - - Updated - - -

A cheap and easy method is to use your arm to cast a shadow over the ball when you want it to move. A simple photosensor circuit might be sufficient. Or cast alternating shadow and light, creating a code which the ball interprets. Reliable operation depends on the size and intensity of the light source. In addition I go along with Brian's suggestion of making the wand transmit IR light.

 

[Gorgon]

I think I would have had the control in the wand, maybe a small omnidirectional camera of the same type used in optical mice.
Make the optics so you look at the size of the ball and that indicates the distance.
If you add a accelerometer so you know the direction of the wand, you can direct the ball via a radio circuit just by rotating the wand.

Another problem is how you make the ball rotate. One way is to shift the center of gravity inside the ball, like a hamster wheel.
The last problem is to do it without sound.