I'm thinking about modifying an rc car with a 9v circuit. In short I want to use an 18v cordless drill battery and motor but to avoid frying the 9v control module I was thinking of using relays with the forward and reverse output from the original 9v circuit as control power and keep the 18v circuit separate. Would love any input
Will it work? What could I do as an alternative? What appliances could I salvage parts from? Trying to just use salvage parts to build this project

 

What appliances could I salvage parts from? Trying to just use salvage parts to build this project

Hey, the Honeydyne 617 has exactly the circuit you are looking for. Salvage the parts from one of those babies.

 

Hey, the Honeydyne 617 has exactly the circuit you are looking for. Salvage the parts from one of those babies.

Thanks, does the mod sound possible? I'm fairly well an amature in electronics

 

First thought (and easiest to do) would be a 9V zener diode 1N5924BRLG 9.1 V, 3.0 W Zener Diode Voltage Regulator to provide the 9V control power.

 

I already have the 9v control power from the rc car unit, I want to get the full 18v from the drill battery to the drive motor. I want to control the drive function with the existing control unit but I can't run the 18v battery through it without frying it. I'm assuming you mean using the diode to regulate the 18v battery at 9v? If so can I do that and use relays to drive the motor at 18v? I was just going to use the 9v battery as well as the 18v but if I can find the right diode I might be able to rig the two circuits to the 18v battery correct?

 

Relays tend to take a lot more abuse without failures than do silicon switching devices.

 

You have an RC car with a 9 volt battery. You want to drive the motor with 18 volts without affecting the 9 volt circuitry. Sounds like a recipe for motor failure. Doubling the voltage of a motor is going to generate a lot more heat. I don't think the motor will survive that. But it's your car. If you want to try running the motor fully loaded (driving the car with the extra battery weight) that's entirely up to you.