What electronic switch should I use?

Question

I am trying to create an electronic trigger system with an airsoft gun.

Requirements:

1. Fire once (rotate motor for one revolution even while trigger held).
2. Fire multiple (rotate motor for as long as trigger is pressed).
3. Safety switch to stop motor if closed.

I am Struggling with req 1 as need to detect a full revolution and then disable motor until trigger released and then repressed.

So far I have one switch for the safety (simple flip switch) which will be put in between power and rest of circuit. I have another normally open button for the trigger which will be placed between motor and safety switch mentioned above. I then have a gear (turned by the motor) which has a part extruding which will press another button.

I’m then wondering how I can implement functionality to stop the motor if the above switch is pressed.

My idea is to add a electronic switch of some kind which is opened by the above switch cutting the power to the motor for as long as the trigger button is pressed and then closed when the trigger is fully released.

I will also need to add a method to choose between req 1 and req 2.

Thanks hope that explains better.

Answer 1

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Simple and complex.

Simple (Figure 1a)

• If safety switch is on and TRIG is pressed the motor will run.
• The motor will continue to run as long as TRIG is pressed.
• When the motor moves away from the home position the CAM switch closes. When TRIG is released CAM will keep the motor running until it reaches the home position and the motor will stop.

Complex (Figure 1b)

For single-shot control we need to check that the trigger has been released before allowing the motor to start again.

• With TRIG in the off position and the CAMb NC contact closed RLY1 will energise indicating that the trigger has been released.
• When TRIG is pressed its NO contact will start the motor via RLY1's contact. CAMa NO contact needs to close very quickly to maintain supply to the motor when RLY1 drops out. The diode helps make RLY1 slow to drop out.
• When the motor reaches the home position CAMa will open and switch off the motor.
• Meanwhile RLY1 can't pick up again until the trigger is released.
• The CONT switch allows continuous running as in Figure 1a.

Answer 2

Here's a solution using relay logic.