I want a device to reduce the speed of a remote controlled toy car. I tried removing some batteries but that wasn't much help.
Bill

 

I want a device to reduce the speed of a remote controlled toy car. I tried removing some batteries but that wasn't much help.
Bill

Welcome to AAC!

We need more information such as the number of batteries and battery type.
In most cases, removing some batteries would make the toy stop working since most times the batteries are wired in series.
If the batteries are wired in parallel, there would be no change in voltage at moderate loads.

You can try putting a high wattage power resistor in series with the motor. We would have to know the motor voltage and current rating in order to suggest a resistance and wattage.

 

The series resistor is the simplest, but it will produce heat that may be a serious problem. Just like an electric heater. Years ago we had a design for a PWM motor controller for a 12 volt motor. It used a 556 dual timer and two NPN transistors and was good for quite a few amps. I can try to dig up the circuit if there is any interest.

 

Can you detect what kind of motor it is, the common DC brushed type or the later brushless types?
For the typical brushed type see a simple 555 circuit here:
gives parts and circuit below the video.

 

Can you detect what kind of motor it is, the common DC brushed type or the later brushless types?
For the typical brushed type see a simple 555 circuit here:
gives parts and circuit below the video.

It will take more than just a 555 timer IC for most motors. Except on the cartoon channel.
I do have the circuit that uses a 556dual timer and two transistors. I have not dug it out yet.\
That circuit DIDuse a 556 DUAL TIMER, withthe first timer producing the voltage ramp wavefor and the secons timer serving as a comparator to produce and adjustable duty cycle waveform. It used two NPN transistors, the first plastic transistor was an amplifier, the second one was good for a few amps at 12 volts. It was a "power-tab device.

 

The OP has what appears to be a simple example of a small DC motor, there are a myriad of examples out there using the 555 this one for example, from my PCB supplier.PCBway.
The 555 obviously uses the correctly selected Mosfet to handle the current??
I have used to use the 555 timer for this simple application many times,

https://www.pcbway.com/project/shareproject/555_Timer_12VDC_Motor_Speed_Controller_053a14bc.html
I would use a Mosfet in this example.
Also