How can I use an Arduino to simulate button presses on this Remote Control PCB

Question

I read with interest here this post: How can I use an Arduino to simulate button presses on this PCB

I am a beginner in this and I am trying to learn how to do this based on a small remote control I would like to simulate a fake press using an arduino.

I am also not sure if I need to use a MOSFET as it is a very small device requiring little amperage so I think a small transistor will do ?

Basically, I would like Arduino to send a signal to the 2 red points here that will simulate a fake button press.

Hope I am making sense here. I appreciate any guidance or pointers on what I need to make this happen. Thanks !

More details to share: With COM on Battery-Negative and the other lead:

• on the right side of the button = 12V. When button is pressed = 12V

• on the left side of the button = 0V. When the button is pressed = 12V.

I will just focus on one button. Disregard the other button.

@Dave Tweed https://electronics.stackexchange.com/users/11683/dave-tweed If you are listening, I would really appreciate if you can share some advice.

Thanks all

Answer 1

This is just the first step towards your goal. You need to figure out whether the buttons, when pressed, connect the chip input to battery negative (pulling the input low) or battery positive (pulling the input high).

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Low-side switching and high-side switching.

• Switch your multimeter to DC volts and connect the COM lead to battery negative.
• Connect the V lead to one side of SW1 and note whether you get a low (0 V) or high (+12 V).
• Now press SW1 and see if the voltage changes. If not then move to the other side of the switch and repeat.
• Repeat the test on the other switch.

If you have the arrangement of Figure 1a the solution may be fairly easy.

Answer 2

Ok. Solved.

5V relay 10A ? VCC to Input, GND to GND and + to 5V and the NO wires connected to the 2 outlined contacts of the RC button. Thanks to @Transistor for the guidance and help.