GD Drive

Wednesday, February 4, 2009
Ok so after I got the CD-Drive working I needed a way to mount the GD-Rom onto the CD-Drive tray. At first my thought was to mount it underneath which would keep the thickness down. Unfortunately as I was thinking about this I decided that this was probably not the best idea because the method in mounting it to the CD tray was using glue. So If someone was a little frustrated they could push too hard and could possibly push the drive off the tray. It would also cause me to have to remove one of the major support beams that connect both sides of the drive mechanism. If I went this method I would have to cut that off and then reinforce it in another way.

So then I thought about placing it on top of the tray. Obviously it wouldn't fit but that is where my good friend the Dremel comes in. I put a disc on my GD-Rom and made a rough trace of it and put it on top of the tray and commenced to dremel. Here was my final product.

From Dreamcast Laptop
CD-Tray cut out.

From Dreamcast Laptop
With the GD-Rom on it.

From Dreamcast Laptop
GD-Rom and CD

I decided to go this route because it would be less of a hassle. More structurally sound, and it didn't add very much height to the system.

GD Drive schematic

Ok so I got the CD-Drive working. For a while now I have been trying to figure out how I was going to get it working and had a few ideas and built a couple prototypes and have finally settled on one that works completely. It uses two 555 timers and 4 sensors, and one button to open and close the drive.

From Dreamcast Laptop

Here is the schematic.

So basically how it works is you have one of the 555's to control when the tray goes out and the other for when it goes in. The 555 that makes it go out, you put the switch/sensor connected to pin 2 of that 555 on the closed side of the tray so that when it is closed it pushes the switch. Put the switch that is connected to pin 4 on the open side so that when it is open it pushes the button/switches the switch.

Then for the 555 that closes it do the opposite. Put the switch connected to pin 2 on the open side and the switch connected to pin 4 on the closed side. Basically what happens is when it is closed you push S1 and that triggers the open 555. When it is open it pushes pin 4 of the opening 555 and resets it sending it back to 0v. It pushes the button connected to pin 2 for the closing 555 so when you push S1 it triggers the closing 555. When it is completely closed it pushes the switch connected to pin 4 of the closing 555 and it sends it back to 0v.

One of the problems I had with this at first was I didn't have the capacitors on it at first and for some reason the circuit would work until I hooked the motor up to it and I'm thinking that the motors induced voltage after it got shut off would cause the 555 that performed the direction opposite to the way it was going (so when it got completely opened it would instantly trigger the closing 555 and begin to close). This would go on endlessly until you took away the power. So I was trying to think of a new way to do it and then I thought about putting in the two capacitors and it worked. Later on I had to switch out the capacitors for some larger 3300uf ones instead because 1000uf didn't seem to be enough. Hooked it up to 12v and all worked.

Video of it working.