Disk Robot
The mechanical system is very fun to watch operate. A nylon plate slides under computer control to push the diskette at the bottom of the stack into the diskette drive. The drive is then tilted down and away from the insertion position to eject the diskette into one of two different bins - a good stack and a reject stack.
Two unipolar driver circuits deliver power to geared stepper motors - one for inserting the diskette, and one for tilting the disk drive to the proper location for loading or ejecting.
It's amazing how much force is required to press the eject button on a typical drive - several pounds. For this, I used a large 110VAC solenoid and a solid state relay. It makes quite a noise.
The controller is an 8052-type programmed in assembly language. It accepts ASCII text commands from a serial port and several controllers can be daisy-chained. The circuit board uses point-to-point wiring and is still operational 10 years after construction.
Controller Board
In this picture you can see the controller board with the serial port. One of the DC power connectors is an input, the other is to daisy-chain to the next unit. On the left you can see the geared stepper which tilts the drive.
Top view
The shute can carry about 100 diskettes. At the top left you can see the stepper motor and timing-belt drive which pushes a sheet of nylon across the bottom of the stack to insert a diskette into the drive.
Diskette Inserter
Here's a closer view of the diskette insertion mechanics. The nylon sheet is guided by two square nylon bearings with grooves. A limit switch on the end of travel tells the controller where the stepper motor is.
Disk Drive Mechanics
Here's the disk drive end showing the tilting motor and also a limit switch. The entire drive can tilt down to two different positions - one for the accept bin, one for the reject bin. What you can't see is the ejector solenoid which is mounted under the disk drive.
End View
Here you can see the disk loading shute and the diskette drive and tilting mechanics. The controller is on the right side and under it you can see the orange solid-state relay which drives the eject solenoid.