[RichD]

Perhaps you are missing nothing. We run without magnets and we run all sorts of cars, so having a better controller is more important. We actually hold races and of course all of our tracks have electronic timing. If you mostly run by yourself or with friends that might drop by from time to time who will use the controllers that you supply you will save money by sticking with that. For the most part I expect that if you race with a club that places no restrictions on controllers you would want to try everything and use the best controller that you can afford.

 

[RichD]

Everyone in my club uses an electronic controller, either a Difalco or a 3rd Eye. One of the club members is a dealer, so we get to try the latest thing. At the end of the day a controller is either going to get you lower lap times or it isn't. I have tried a few controllers with adjustments that didn't seem to do much. Having an almost infinate number of adjustments is not always going to be a good thing, with too many adjustments finding that perfect combination could be like finding a needle in a haystack. I use a Difalco Genesis, it has 30 bands and the entire resistor network can be swapped for one with a different total value or for a custom made on that does not have linear steps. The controller has the heat sink, transistor and two relays mounted at the plug end. Power for the car does not go up to the handle and back. There is a 30 amp blast relay for full speed and a 10 amp relay for full brakes. When the brake control on the handle is used the brake relay is bypassed. The sensitivity control on the handle adjusts the point on the trigger pull where your car will start to get power, that is especially useful if you run on tracks with different voltages. The final control on the handle is the choke or "anti spin" control, it limits the maximum voltage that the car will see, which is useful if you are trying to drive an overpowered car. On my controller that feature is bypassed at full throttle, the controller can be ordered with a switch that disables the blast relay. With that swich on the car would not get full power at full throttle with the choke control turned up.
One drawback to some electronic controllers is that they do not have fine enough control. Most of them use resistors connected to the bands on the wiper pad. Because of the size of the wiper button there is a practical limit to how many bands the controller can have. Resistor controllers have a possible advantage in that respect, each turn of the wire is another band. 3rd Eye controllers have a wire wound resistor in place of the more common wiper pad and Slot.it controllers use a Hall effect sensor.

 

[RichD]

It would be better if you could try the controller before you bought it. Besides having all of the desirable features it is important for the controller to feel right in your hand and if you race it is nice to have one that won't fall apart in the middle of a big event or get cooked if you hook it up wrong. My Difalco has a resetable fuse and diodes for protection and if those were not enough the only part likely to fail is the transistor, which is cheap and easy to replace.

 

[RichD]

You can add variable brakes to a controller by putting a 25 ohm potentiometer in the brake circuit. With resistor controllers you can lower the effective ohm value by wiring a second resistor in parallel with the original resistor. The second resistor can be a fixed or variable type, but either way it is better to use something with a ceramic core. There is a pitfall to using a parallel resistor, the controller will not be linear. At the start of the trigger pull the controller will act like it had a lower ohm value, at the other end of the trigger pull the controller will feel more like it did without the extra resistor. I tried this trick once, I started with a 45 ohm controller and put a 500 ohm rheostat in parallel. I also had a bypass switch to take the rheostat out of the circuit. With the rheostat adjusted properly the effective resistance at the beginning would be 25 ohms, but the controller did not really feel like a 25 ohm controller. Since adding a fixed parallel resistor is a cheap modification you could add a 50 ohm resistor to get about 24 ohms or a 150 ohm fixed resistor to get about 35 ohms. Give that a try and see how you like it.

 

[RichD]

If you were to add a fixed resistor in series with the one in a Parma Economy controller you would not be able to get full power. You would have to modify the controller to add a full speed contact like Plus and Turbo controllers have. As someone pointed out there would be a considerable gap between the voltage at the full power end of the resistor and the full power contact which could be a problem. Building your own controller is a nice project, what would be the total cost of the parts? One would have to source the parts and perhaps pay postage, which gets more expensive if you can't get all of them from the same place.