Help building single revolution motor/servo/stepper circuit

[llphil67]

I am trying to design a system that will trigger a motor/servo/stepper to rotate one full revolution only. This is not the project, but is an example: a coin rolls over a microswitch which triggers a motor to make exactly one revolution and stop, ready for another coin drop to repeat process. I am very new to this so I will need to know specifically what I need to obtain and how to build the system. Thank You in advance.

 

[rjenkinsgb]

The simplest setup would be a geared DC motor with a cam attached to the output shaft, as well as whatever it drives.
(Gearing reduces the speed and gives things time to happen, plus vastly increasing the motor torque).

The cam needs to operate a microswitch at the "zero" position of the shaft rotation. The switch breaks the circuit and stops the motor.

The trigger switch just connects across the stop switch to make the motor run past the stop position, so the stop switch releases and keeps power on to the motor.

That's how simple mechanical car windscreen wipers stop in the "parked" position - a contact or switch that keeps power on until they get to the right point.

You could also use the stop switch to operate a relay that controls power to the motor. Having that connect a low value resistor across the motor when it releases would give a more accurate fast stop rather than the motor coasting on a bit.

Example geared motors; the type you need depends on how fast it must and how much power the output shaft needs:

N20 DC Geared Motor 3V, 6V, 12V 3mm Shaft Arduino PICAXE Raspberry PI UK Seller | eBay

N20 DC geared motor, 3V, 6V, 12V various RPM. · UK based supplier.

www.ebay.co.uk

Reversible Torque Turbo Worm Geared DC 12V Motors GW370 12V 0.6 - 120RPM | eBay

The worm gear motor with self-locking, ie, in the case in the absence of electric motors. 1 Geared Motor. Load torque: 10KG. No-load speed choice:0.6rpm/10rpm/25rpm/100rpm/120rpm. Material:416 Stainless.

www.ebay.co.uk

DC 12V Large Torque Mini N20 Worm Gear Motor Full Metal Gearbox Robot 16-381RPM | eBay

• Low speed, Can be forward and reverse. • DC Deceleration. Good Good quality.

www.ebay.co.uk

If it's something that must operate fast. eg. less than a second for a turn, you are probably going to need a more sophisticated and much more complex system.

 

[danadak]

The simple method described above excellent. But if there is a coin jam,
wrong size coin, another countries coin sized different, you could stall
the motor.

Using a micro and a RC 360 degree servo motor you could detect motor current
and manage a stall, even reverse motor to possibly unfreeze jam.

Regards, Dana.

 

[tepalia02]

I think a coin sensor should be added to the system.

 

[Pommie]

This is not the project, but is an example:

Looks like the last two posters missed this part. Plus 1 for RJ.

Mike.
Edit, the voting system appears to have disappeared.

 

[vu2nan]

Here's a circuit that utilizes a microswitch and a momentary push button switch.

The microswitch is to get actuated once per revolution. Its 'NC' contact is used.

Actuation of the momentary push button switch starts the motor.

The push button is to be released when the microswitch gets released.

Re-actuation of the microswitch, after one revolution, stops the motor.

Nandu.

 

[shortbus=]

This is a necropost guys. The TS hasn't been here since May 15 2022, two days after the question was asked.