Since my previous post about making a Go Baby Go car with motorized steering a few people have reached out to me with questions about the process. In response I’m offering here a much simpler to produce adaptation. To recap, this type of car can be really fun and useful for a child who is not able to use the original gas pedal and steering wheel. The previous method I presented required modifying the frame of the car and installing your own motor that would control the steering. As presented, it also involved installing and wiring up a pot to detect the current steering position and a microcontroller to monitor and control the steering. That setup affords a lot of control and flexibility but at a higher price of time and effort. The videos below show the result of the much simpler method of switch adapting the remote control of a ride on car with built-in motorized steering.
Switch adapting the remote control was mostly straightforward. You can see the steps I took in the pictures below.
The one unusual step I took was shorting out 2 capacitors as pictured below to bypass them. Their function in the circuit was to limit how long the right and left turn commands could be sent.
I suspect the steering motor does not have any limit switches and they did not want someone forcing the motor against either of its stops for too long and possibly damaging it. This was a quick fix on their part and does somewhat lower the chance for damage, but this safety is not effective against repeatedly releasing and pressing again in the same given direction. Since these caps did from my testing cause usability issues with different lengths and types of switch cable, I chose to bypass them. If this safety is desired then they can be left in place and switches with shorter cables can be chosen. Or, the safety can be best re-implemented with limit switches added on the car for the steering.
Once the remote controller is switch adapted you can of course use any type and combination of accessibility switches you wish including buttons, joystick, sip-n-puff, etc. Here are some pictures of the joystick and bracket that I modified to have switch jack outputs.
This car I modified is a 12V Ride On Sports Car w/ Parent Control from BestChoiceProducts. Although not needed for this method of modification, below are pictures of the car’s receiver and the PCB inside (located under the seat and near the battery) for reference. The remote transmitter uses a PT8A977BWE and the care receiver uses a PT8A978BLWE. You can view the datasheet for those ICs here.
You could of course take the remote control out of the equation one of 2 ways. You can disconnect the motor connections from the car’s control electronics pictured above, and connect them to your own control circuit which will use switches as inputs. At that point you could ditch the existing PCB or keep it to control the car lights and sounds.
The other option is to keep this PCB, but remove just the receiver chip and drive the 4 relevant pads (Forward, Backward, Right, Left) directly. You could do this by adding your own microcontroller such as an Arduino, or more simply with the switch jacks (one side tied to VCC) and the other side on the target pad with a pull-down resistor.