I have a large HO slot car racing set, which is a great hit at any parties we have at home. After the kids are allowed to play on it for ten minutes or so, they are invariably unceremoniously booted off by their dads who go at it with an enthusiasm and verve that is always great fun to see.
However, remembering that the paragraph above stated the word 'party' with all the attendant drinks, it tends to get a bit problematic due to the ten tons of spaghetti connecting everything, and most importantly the hand held controllers. Despite me making a dedicated junction box and extension cables so that the drivers are at a station away from the track, there are still always the moments when someone is forgetting that they are holding the controller and starts moving around. This ends up either disconnecting stuff as plugs are pulled out, or in extreme cases the track gets pulled apart. Necessarily all the contact points to the track have to be sited at a point between the driver station and the track, rather than being tucked away in a corner away from harm.
The physical setup of the wired controller is very simple, essentially a wirebound rheostat with a sprung wiper that is directly actuated by the trigger. This is housed in a pistol grip shaped plastic housing, and the power from the 22v power source is passed to the rheostat, and the resistance due to the position of the wiper reduces the voltage out that is then send back to the track contact strip.
So my thinking is that if I can have wireless controllers that connect to a base unit on the far side of the track, it will massively help all this.
some other design considerations
up to eight cars are controlled on the track, so whatever it is needs to have discrete channels
Each lane (car) requires 18 to 22 V DC at a max of 2 amps; the power supply is taken care of by an external unit and can be either 1 large unit with enough to supply all 8 cars, or each car can have an individual power supply unit. I have no preference as to which
I have a 3D printer and CNC machining facilities so I can make a suitable trigger grip housing for the hand held unit, but obviously will have to have some kind of battery with it. The physical size and weight should not be too big for comfort so the electronics presumably have to have low consumption and be compact.
I wish to maintain the sprung finger actuated control method.
The recommended resistance of the controllers is apparently 45 Ohm for the types of cars I have
There is a way of providing a braking effect using a shunt so when power is removed it slows the cars down faster; at some point I would like to incorporate this but am happy to wait for this until later.
So with the above in mind, I am looking for ideas and suggestions as to alternate ways to achieve this. I see the project broken into 2 parts, the hand controller and wireless link to the master controller, and the motor control units and their actuation
Staring with the motor control, one way I thought of was to have the existing physical controllers mounted in a suitable fixed housing with a servo motor actuating the trigger via a mechanical linkage. The output from the controller would then control the servo via an arduino output. This means keeping a lot of the existing hardware and using the electronics to just control the servo position.
The other way would be maybe a PWM output, however I am aware that the voltage and current involved exceeds the capabilities of the arduinos. The advantage would be that it is solid state and probably would also be a lot more compact and ultimately more reliable.
On the controller side, I know the R/C aircraft crowd use multi-channel receivers and transmitters to control the various servos, but the transmitter is an all in one box. I need up to eight discrete controllers. So is Bluetooth a possibility, so that the channels do not interfere? Obviously the channels have to be separate so that they do not interfere. The range over which they would have to operate would be up to about 15 metres, but a lower range would be acceptable if necessary.
So at this point I would like to ask you all for ideas and feedback on my suggestions and project above, and would welcome any suggestions on solutions that differ to my proposals. Let ma know of any questions or if I have left any detail out