Basic Wiring: Determine what happens when a button pressed in existing device?

Hi everyone,

I have a (probably) basic question: I’m trying to use a toy shotgun in an arduino project. The toy is electronic and makes sounds at two events:

a. Trigger Pull
b. Reload

Now. I’m, at best, an advanced novice. I have a multimeter, and I know enough to use it to determine whether or not two different points are connected.

The toy has three wires coming into the handle (attached photo, A, B, C). I learned that if I connected A and B to the board, using a basic push button set up, I could determine when the trigger pulled.

The third wire (C), I’m ASSUMING is connected to the reload event, but why isn’t there a secondary ground (or negative or…?) for that button/switch? Can these two switches share the same circuit?

Bigger picture, I guess: In general, is there a way to use a multimeter with a cable (or cables) in this context?





You only need one GND connection for multiple switches.

That's what I thought, so I tried connecting that wire to the board in the exact same place as the existing trigger, and it never detected any switching whenever I reloaded the toy.

I'm also a bit confused as to why they might've used a red for the ground and green for the lead, so I tried reversing them (and the original trigger fires as expected), but even then,when substituting the third (wire? lead?) nothing fired when initiating that particular trigger.


is there a way to use a multimeter with a cable (or cables) in this context?

Remove the battery from the toy.
Use the ohmmeter and probe the wires, looking for a change in resistance when clicking the switches.
If that proves fruitless, place the battery back in the toy and use the DC voltmeter, looking for voltage changes when clicking the switches.

You know, I tried that, and had no luck. Although to be honest I'm just sort of winging it when it comes to "probing the wires."

This multimeter thinggy has a number of different modes, (although just to be thorough I tried all of them) and I think I tried all the permutations of the wires and the leads, and while the first button definitely beeped in logic mode, I never got the 2nd button to do anything.

Although if it's chained together in someway, do I have to have both of the trigger wires connected or... I dunno I'm sorta stumped.

(also since I , stupidly, removed the wires from the thing pre-emptively, I don't think I can do the voltimeter test)


First, you need to learn how to use your meter. You cannot just try all the permutations. Some will damage the meter, some will damage the circuit.

That red wire may not be ground, it could be connected to V+.

Does the toy still work?

Where are the switches for the trigger and reload?

First, thanks Polymorph for helping!

Second, the triggers are in the housing.

I purchased a second gun (only like $15) so that I could test before dismantling.

Here’s my first “test.” I apologize for being kind of ign’ant.


(If I move the RED lead to the contact point south west, I get the same behavior with the reload trigger.)