Servo advice

[dfox1787]

Hi guys

im after a servo that when powered has a see-saw affect.

this project is a marble dropper. is lets one marble release while loading the next one.

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[Al_The_Man]

May be simpler to go with a stepper in this application.
What form does the controller have? I assume you want the action to be automatic?
Or are you using a RC servo as shown?
You can make a controller from Arduino or any small picmicro, you may find something simple on ebay.
Al.

[BBMNet]

Hello.

Without seeing an actual picture of your mechanical device I´d say you can go with a small DC motor with an integral speed reducer. Since the motor turns freely there is no need to turn it back. A rotating bar with pins at the ends could release one marble while admiting the next one. The length of the bar should be sized according to the space between marbles.

For the option using reciprocating (see-saw) motion, it can be accomplished with servos like the one depicted as there is some internal mechanism that returns the motor back to its initial position. Using two limit switches and a DPDT relay it would be possible to implement such a device.

When the motor is at is initial position the first limit switch should activate the relay which uses one set of its contacts to keep the relay at its ON position. The second set of contacts is used to drive the motor.

When the exiting marble hits the second limit switch the relay is set to its OFF position thus disconnecting the motor which is returned to its initial position. When hiting the first limit switch the cycle repeats.


| LS1 LS2 RELAY LS1: Limit switch at the feed point.
|----| |---------|/|--------(K)----| LS2; Limit switch at the exit point.
| NO | NC | K : Relay.
| | | M : Motor
| K1 | |
|----| |---- | K1 : Set 1 of the relay contacts
| NO | K2 : Set 2 of the relay contacts.
| |
| K2 |
|----| |-------------------(M)----| NO: Normally open.
| | NC: Normally closed.
GND +12V

I hope this can give you an idea.

It would be possible to add a sensor so that movement stops if the system runs out of marbles. While that would be possible using another limit switch and probably a timer using an NE555 chip to implement it, in this particular case I would go with a system based on a PIC12F675 (a pic12F508 would do the job nicely but I happen to have 675´s in stock). That I assume is beyond your requirements so I won´t further elucidate on that. However if you want to know more please let me know.

Regards.