C945 Transistor to Arduino UNO not working - Turning Remote Control Car ON/OFF

Hey guys. I have a problem that I need help with solving

I have taken a remote control car apart and I want to turn it on and off using an Arduino Uno

I have soldered off the VCC and Ground wires from the manual on and off switch which were at the bottom of the car and I have taken a small circuit board and soldered them onto the board.

I have then soldered a transistor onto that board in a way where the VCC from the RC Car is in line with the transistor collector and ground from the RC Car is in line with the Emitter. I’m using the C945 P331 Transistor who’s PIN out/data sheet can be found here. http://www.ges.cz/sheets/2/2sc945.pdf

I know that transistors are the digital switches which can help me achieve my objective.

Also on this little board I have soldered the Base of the transistor in line with a resistor and then I’ve soldered a jumper cable in line with the resistor.

The idea is that I can connect the other end of the jumper cable into an Arduino Uno, give the Arduino code to give the PIN voltage for 10 seconds then withdraw voltage for 10 seconds and yeah.

The remote controlled car has batteries inside it btw.

So basically I want to open and close the circuit using an Arduino command.

So now after connecting my jumper cable to the arduino and running the code, and trying to drive the car within the 10 seconds, nothing happens. When I use the RC Remote to drive the car nothing happens!!

However, when I close the circuit by touching the end of the jumper cable together with the VCC and Ground solder, while driving the car using the remote control, THE CAR DRIVES

So it seems that the circuit IS working to an extent because when connecting the Jumper cable to the VCC and Ground solder together to “close the circuit” the car drives… But something is preventing my arduino from controlling the car.

I’ve connected the Jumper Cable to Data PIN 13 because the blink code uses PIN 13

Or perhaps there is a problem with my code

It’s attached below, check it out


Turns a RC Car on for ten seconds, then off for ten seconds, repeatedly.
On the UNO, MEGA and ZERO, it is attached to digital pin 13, o

 This example code is in the public domain.


// the setup function runs once when you press reset or power the board
void setup() {
 // initialize digital pin LED_BUILTIN as an output.

// the loop function runs over and over again forever
void loop() {
 digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
 delay(10000);                       // wait for a second
 digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
 delay(10000);                       // wait for a second

Please help me
Strathmore University
Nairobi, Kenya
Bachelor of Science in Telecommunications

Attached below are photos of how my circuit looks

Did you also connect Arduino ground to emitter.

Hey Wawa
Yeah, I made sure that the emitter of the transistor is in line with the ground from the RC car

Did you also connect Arduino ground to emitter.

Please check out the photos I've attached. You'll see exactly how the transistor and cables from the RC car are layed out. Thanks in advance

I only see one wire going to the Arduino.
Current needs two wires to flow.
Two wires for the car current and two wires for the Arduino current.

Where should the 2nd wire go? and where should it come from?

Emitter of the transistor also to Arduino ground.
Base resistor (black wire) to the Arduino output pin.

Should I connect the emitter to the arduino ground pin by soldering the jumper cable unto the already soldered emitter? Thanks so much in advance

By soldering a second jumper cable to the emitter.

Thank You!

It worked!!