Faller Jupiter Ferris Wheel 140470 / 140471 - Construction Log















































Video@YouTube


Enhancement & Control Box Project

Aim of Project:
To create a Control Box for the Jupiter Ferris Wheel that will incorporate an automatic loading/unloading sequence.
The Loading Area is designed to load 5 cars at a time (although strangely, there are 36 cars). The plan is to place seven small magnets around the back of the Wheel and a reed switch on one of the main supports. As one of the magnets passes and activates the reed switch, the Wheel will be programmed to stop. After a designated time period, the Wheel will advance slowly to the next magnet and stop again. Once all 7 sets of cars have been loaded (I'll ignore the 36th car), the 'ride' will start.
The whole sequence will repeat after the Wheel has made a number of revolutions.

Like my homemade Indiago, Octopussy and Paris-Dakar Go Kart Control Boxes, I will use a programmable Picaxe chip to control the Wheel and to detect the activation of the reed switch.

Phase 1 - Modifications to Wheel

The first task was to add the magnets to the Wheel. I'm using 3mm Neodymium Cube Magnets. These magnets would fit perfectly on the outer edge of the Wheel if it wasn't for the drive wheel, which has a small rim on it that would keep striking the magnets. For this reason, I've had to set the magnets slightly off-centre.
The reed switch was been attached to the same support as the drive wheel. The wires on the reed switch will eventually be laid neatly around the edge of the model.


One of seven 3mm Neodymium Cube Magnets attached to the rear of the Wheel.
The reed switch has been glued to one of the supports.



One of the magnets positioned directly opposite the reed switch.
The distance between them is sufficient for the reed switch to be activated.


Phase 2 - Prototyping

As with past projects, I built a prototype circuit on a breadboard. All that this circuit needs to control is one motor and a reed switch - the same as the Octopussy model - and in fact, the circuit is virtually identical to the Octopussy prototype circuit. The main difference is that I found that because the Jupiter motor only needs 1.25v(*), using Pulse Width Modulation to reduce 5v down to 1.25v didn't work very well (the motor didn't run smoothly and became quite noisy). I had to take a different approach. I ended up using a component I hadn't used before - an Adjustable Voltage Regulator - where you get the output voltage you want by connecting resistors to its pins according to a formula. The formula didn't work that well for me (I guess there were other factors in the circuit that affected the output voltage), so ultimately it was a case of trial and error, but eventally I got the voltage I wanted.

(*) The maximum voltage that can be applied to the motor (without damaging it) is 3v. The circuit board that Faller supplies with the Jupiter Ferris Wheel contains a potentiometer that allows you to vary the speed of the motor. For me, the best speed was produced when the potentiometer was set to deliver 1.25v.

This is what I ended up with:



And this is the flow diagram of the above circuit (produced using TinyCAD):



The illuminated Jupiter sign and Column lighting which come as part of the Jupiter Lighting Kit will also be powered by the Control Box (shown by the EL+ & EL- terminals in the flow diagram).

Phase 3 - Software

When power is connected, if one of the magnets is not already directly opposite the reed switch, then the wheel will advance slowly (using PWM) to the first magnet it finds and then stop.
After 7 seconds, the wheel will rotate slowly to the next magnet and stop again. This will be repeated until all the cars have have been serviced.
The main 'ride' will then start.
As the wheel rotates, the reed switch will be monitored and the pulses generated as the magnets pass will be counted. After a certain number of pulses, the wheel will slow down and stop when the next magnet faces the reed switch - the aim here will be to stop the wheel at the same group of cars that were loaded first.
The whole sequence will then repeat.

This is the code that I've currently got loaded on the Picaxe chip:

symbol magpulse = b0
symbol outer = b2
symbol inner = b3
main:
	gosub locatestart
	pause 7000
	for outer = 1 to 6
		gosub loading
	next outer
	gosub ride
	goto main
	end

locatestart:
	do while pin2 = 0
		high 0
		pause 1
		low 0
		pause 1
	loop
	for inner = 1 to 100
		high 0
		pause 1
		low 0
		pause 3
	next inner
	return

loading:
	for inner = 1 to 100
		high 0
		pause 1
		low 0
		pause 3
	next inner
	do while pin2 = 0
		high 0
		pause 1
		low 0
		pause 1
	loop
	for inner = 1 to 100
		high 0
		pause 1
		low 0
		pause 3
	next inner
	pause 7000
	return
	
ride:
	for inner = 1 to 100
		high 0
		pause 1
		low 0
		pause 3
	next inner
	for inner = 1 to 200
		high 0
		pause 1
		low 0
		pause 1
	next inner
	for inner = 1 to 200
		high 0
		pause 2
		low 0
		pause 1
	next inner
	high 0
	let magpulse = 0
	do while magpulse < 49
		if pin2 = 1 then
			inc magpulse
			pause 500
		endif
	loop
	for inner = 1 to 200
		high 0
		pause 2
		low 0
		pause 1
	next inner
	return
;           COMMENTS 
;
;
;main:
;
;
;
;
;
;
;
;
;
;locatestart:
;	locate next magnet
;	  {
;         {use PWM to run motor
;         {slowly
;         {
;
;	advance past magnet to 
;	line up cars more accurately
;       with steps
;	- motor running very slowly
;
;
;
;
;loading:
;	start motor running very slowly
;	
;	
;	
;	
;	
;	increase motor speed and advance
;	to next magnet
;	
;	
;	
;	
;	decrease motor speed
;	move past magnet to accurately
;       line up cars with steps
;
;
;	
;	wait 7 seconds for cars to load
;       	
;
;ride:
;	start motor running very slowly
;	
;	
;	
;	
;	
;	increase motor speed
;	
;	
;	
;	
;	
;	increase motor speed
;
;
;
;
;
;       set motor to run at standard speed
;	
;	count pulses generated by magnets
;	- allow 0.5 secs for magnet to pass
;	  by before looking for next pulse 
;
;
;
;       decrease motor speed	
;
;
;
;
;
;	

Phase 4 - Stripboard Layout

I've arranged the components of the flow diagram (from Phase 2) into the following stripboard layout (using VeeCAD Stripboard Editor):



Key Component Value Purpose (as I understand it)
C3 / D1 Capacitor / Diode 100nF / 1N4001 To reduce high-frequency interference and absorb back emf.
T1 / T2 Transistor BC337 To amplify the small current from the chip sufficiently to drive the motor.
BR1 Bridge Rectifier W02M Used here to allow DC connection pin to be positive or negative.
R2 / R3 Resistor 1k / 10k / 1k / 10k Used to divert a small current to an input pin when the reed switch is closed.
R4 Resistor 10k Restrict current flow through chip to the transistors.
R5 / R6 / R7 Resistor 4k7 / 10k / 20k Recommended connections / values by Picaxe
R8 / R9 Resistor 510R / 330R Used in conjuction with Adjustable Voltage Regulator.
U1 Programmable Chip PICAXE-18X Picaxe Programmable Chip
U2 Voltage Regulator L7805CV Converts input DC (in this case 9v DC) to 5vDC.
U3 Adjustable Voltage Regulator LM317T Used here with R8 & R9 to reduce 5v DC to 1.25v DC.
C1 / C2 Capacitor 100nF / 100uF Smoothes the DC output from the Voltage Regulator


Phase 5 - Building

The reverse side of the stripboard with cuts applied and components ready for assembly.













And here's a video showing the model working with the Control Box:

http://www.youtube.com/watch?v=PHvegnNJUX4



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