Backyard Aquaponics
A place to discuss aquaponics

If it is a stepper motor you have a much bigger task getting it going

And a stepper motor makes sense for the focus motor.

Unfortunately/fortunately I think I need to understand stepper motors, because I think they will work for me in all kinds of applications, and will be almost essential for the full size solar tracker.

Lucky for me there has been lots of work done on picaxe with stepper motors for robotics. I think I can just copy and past some subroutines and just call lumps of code to drive forward x steps, backwards x steps.

I hope.

I still haven't really explored it other than a bit of window shopping.

It does look complicated, but I think there is more stuff out there on stepper motors than almost everything else.

Wanted. Robot geek. Must be willing to work for baked goods, bacon based finger food, praise, and the promise of thanks. .

It gets strange tho.

The motor that moves the laser along it's track uses teeth along the slider exposed to a 90 degree cog on the motor.

Direct drive.

I cant imagine how they can move a laser accurately enough with a direct drive from a 5v motor with no gearing, and no stepper tech. Just a scalelectric 90 degree kind of drive that sends the slide flat out to the other end when you touch the wires for a zillionth of a second..

I thought lasers would need insane precision. Perhaps they can read CDs much quicker than I thought, and just buffer the entire disk or something.

Even if it were a stepper (It's definitely not, just two wires and when connected to 5v it spins) with all the 1/4 stops between each cog, I cant imagine it could be moved with the finesse to follow one track from a CD. Clearly CDs don't work like vinyl, but no doubt everyone who isn't me already knew that

When I pull a disk from a drive it's hot.

Is this from the laser, or just from the more believable physics of motors getting hot?

If it's from the laser, I've got an idea.

The laser head drive is coarse because it doesn't need to be accurate.

There is a fine tuning mechanism in the laser head itself, that consists of a couple of sensors, and some very fast but small actuators. This system allows the laser to track the pits in the cd, even when the cd is slightly off centre or wobbly. It's fast enough to realign at least twice in a cd's revolution, probably much faster.


It's amazing, very clever tech :-)

Oh, and BW:

Do not look into laser with remaining eye

Thanks for that

A had a bit more of a poke around in what's left of the drive. That final adjustment is sooo delicate.

The entire thing is incredibly well made. The motors are good quality. The case has a zillion screws holding everything in place.

This is a very old cd drive and I suspect it would have sold for $100 or so. I doubt a new drive would be so well made.

I just shorted the capacitor after breaking it out of the dead camera.

Big bada bang.

Lots of noise, and a crazy spark like an arc welder.

330v 80uf doesnt seem like it should pack such a punch. Does it's power come from how quickly it can discharge?

It's smaller than a AAA battery.

80u is a fair bit, especially with 330v on it.