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Topic: HELP!! I'm New to the whole arduino thing. (Read 7483 times) previous topic - next topic

Grumpy_Mike

It looks like your CD drive has a stepping motor to move the read / write head. From a pile of scrap CD drives I had to make this project there were about a third of them like that. I had two with brush-less DC motors and conventional motors in the rest.

However, what they were talking about is the motor that opens and closes the sliding door or CD eject mechanism, I found all of these were DC motors wit an arrangement of slides and gears to change direction. Out of 25 CD drives I took apart no two were exactly the same, even those that were supposed to be the same brand so it is not feasible to provide step by step instructions.

AWOL

If the motor you have has a long (4 or 5 cm) shaft with long-pitch screw thread, then that is the head-drive, and as Mike says, is usually a stepper.

The drawer motor is often a flat motor with a single small pinion gear on a very short (4-5mm) shaft.

marquita188

#17
Jun 29, 2011, 01:02 am Last Edit: Jun 29, 2011, 01:15 am by marquita188 Reason: 1
Now I'm thinking, I'll just do the gravity way, by using the CD drive, tension springs, adjustable curtain rods.
but how do i jury-rig the push button on the CD drive?

greywolf001au

I'm pretty new to this stuff to but why not use a solenoid (or something to that effect) instead of a servo/motor/cd-drive, i simple pull motion when power is applied then would only need to be connected via a hinge (not even for a sliding door) and not have a need for gears/pulleys or any of that stuff.

I'd be looking at diminishing the time taken and noise created for the door to open so as to not deter the cats from using it (I have a jumpy cat that will not use a normal cat door), the cd-drive could be a little slow to open the door as it takes a fair bit time just to open the tray which only moves a few inches. You also then only have a plastic gear which you could buy at Jaycar for next to nothing.

marquita188


I'm pretty new to this stuff to but why not use a solenoid (or something to that effect) instead of a servo/motor/cd-drive, i simple pull motion when power is applied then would only need to be connected via a hinge (not even for a sliding door) and not have a need for gears/pulleys or any of that stuff.

I'd be looking at diminishing the time taken and noise created for the door to open so as to not deter the cats from using it (I have a jumpy cat that will not use a normal cat door), the cd-drive could be a little slow to open the door as it takes a fair bit time just to open the tray which only moves a few inches. You also then only have a plastic gear which you could buy at Jaycar for next to nothing.



whats solenoid? how can i make/build what's your talking about?

greywolf001au

#20
Jun 29, 2011, 04:02 am Last Edit: Jun 29, 2011, 04:06 am by greywolf001au Reason: 1
a solenoid is similar to a dc motor but has the electro-magnet at the rear not wound around the stack housing the shaft, when power is applied the electro-magnet pulls the shaft back in to the housing, when power is cut springs pull the shaft out. These can be bought from stores such as Jaycar, a push/pull solenoid was used in the "putting partner" devices (golf training device) for returning the ball.

marquita188

#21
Jun 29, 2011, 04:40 am Last Edit: Jun 29, 2011, 04:50 am by marquita188 Reason: 1

a solenoid is similar to a dc motor but has the electro-magnet at the rear not wound around the stack housing the shaft, when power is applied the electro-magnet pulls the shaft back in to the housing, when power is cut springs pull the shaft out. These can be bought from stores such as Jaycar, a push/pull solenoid was used in the "putting partner" devices (golf training device) for returning the ball.


which 1 should i get, and how much do that cost?
how would i put it on the cat door?
i want to use it without a PC.

greywolf001au

I would speak to the people at your local electronics parts shop as to which one would be most suitable however I would be looking for one that has a decent range of movement so you do not have to attach it to close to the hinge on the door, the closer to the hinge you get the greater the power required to pull it open. Other than that you want to make sure it works so that when power is applied the shaft is drawn back and therefore only requiring power to open the door not to keep it closed.

as far as attaching it to the cat door, if it is a hinged door (flap) you may need one either side mounted to the actual (human sized) door. the shaft then attaches to the cat door using a hinge (elbow joint). You could use the dc power adapter on the Arduino and 5 volt rail to power the solenoid, using capacitors or an extra power feed if required. unsure on the operating voltage although I am sure there is a range to choose from.

Cost would vary depending on the solenoid, its uses and where you are in the world. In Australia it would cost between $10 and $30 dollars for standard application solenoid, more for industrial type.

BTW jury rigging a cd-drives eject button would only be a matter of removing it and attaching the contacts to a pin on your Arduino and sending either high or low signal.

I do not suspect your cats will press a button in which case you need a pressure switch, light sensor or infrared beam in place of the button. A light sensor would need to be mounted very specifically so as to not open the door when the sun goes down. Not sure but from what I learned yesterday about floating pins this may be used to sense if a cat has walked between 2 probes but how to do that, if it would work on that scale or if it would be reliable I am unsure.

marquita188


I would speak to the people at your local electronics parts shop as to which one would be most suitable however I would be looking for one that has a decent range of movement so you do not have to attach it to close to the hinge on the door, the closer to the hinge you get the greater the power required to pull it open. Other than that you want to make sure it works so that when power is applied the shaft is drawn back and therefore only requiring power to open the door not to keep it closed.

as far as attaching it to the cat door, if it is a hinged door (flap) you may need one either side mounted to the actual (human sized) door. the shaft then attaches to the cat door using a hinge (elbow joint). You could use the dc power adapter on the Arduino and 5 volt rail to power the solenoid, using capacitors or an extra power feed if required. unsure on the operating voltage although I am sure there is a range to choose from.

Cost would vary depending on the solenoid, its uses and where you are in the world. In Australia it would cost between $10 and $30 dollars for standard application solenoid, more for industrial type.

BTW jury rigging a cd-drives eject button would only be a matter of removing it and attaching the contacts to a pin on your Arduino and sending either high or low signal.

I do not suspect your cats will press a button in which case you need a pressure switch, light sensor or infrared beam in place of the button. A light sensor would need to be mounted very specifically so as to not open the door when the sun goes down. Not sure but from what I learned yesterday about floating pins this may be used to sense if a cat has walked between 2 probes but how to do that, if it would work on that scale or if it would be reliable I am unsure.


and how would i connect a pressure switch, light sensor or infrared beam to the CD drive push button?

greywolf001au

That way you would connect the switch or sensor to a pin on your arduino designated as an input (see switch example sketch) then use an ouput pin on the arduino to allow power to the cd-drives button (blink example), doing it this way you would need to make a jumper to go across the cd-drives power pins (completing the circuit). This could be done in the opposite way where your output connects to power pins on drive and the button is replaced with a wire to jump across the contacts

It would be much easier to bypass the button altogether and connect your output pin directly to the cd-drive motor, set pin high and motor comes on, set it low motor switches off.

To use a cd-drive you will need to leave most of the tray intact so you have all the plastic bits to push the switches which then reverses the direction of the motor, you could attach this to another pin on your arduino and use software to decide which direction it should be moving.

I'd be surprised if a cd-drive motor would have enough power to lift a cat door without burning out,  stripping the plastic gear or snapping the little rubber bands on the pulleys first.

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