CD/DVD Open/Close Motor Control Circuit Advice

Thread Starter

mackwhyte

Joined Jun 14, 2017
3
Hi, This is my first post so I'll try and be as clear as possible and straight to the point. I am trying to create a circuit to take over the operation of an old CD Drive I have, Specifically the Open and Close operation as the laser assembly is being replaced with a custom assembly.
The Drive has 2 optocouplers to sense CD Position and a Mechanical limit switch to Sense that the drive is fully closed as well as a push button to Open/Close. I was planning on connecting the Open/Close button to a T-Flip Flop using a 555 as a Clock, then connecting each output to a H-Bridge to control the Motor direction. My problem comes when trying to integrate limits when the motor reaches full travel.

Close/Load Cycle consists of: Optocoupler2 Senses Disc,Motor Starts Clockwise, Hits Limit switch, Motor Stops
Open/Eject consists of: Push Button Pressed (whilst Optocoupler1 senses Disc), Motor Starts Anticlockwise, Optocoupler no longer senses Disc, Motor Stops

So both cycles are very similar with a momentary action starting the motor until a switch stops it. I know I could achieve this with a microcontroller but would like to find a solution that does not require it. (Mainly because i don't have much experience in programming unfortunately)

Another issue I was thinking of was if the Load cycle failed i.e the drive loaded the mechanism in but the disc somehow escaped, this would stop the Eject cycle working as Optocoupler would not be triggered, and omitting optocoupler from the Eject cycle would mean there would be no limit to stop the Motor meaning it would run continuously, so i was thinking of having an alternative Eject cycle where if the optocoupler was not triggered, when the Push button was pressed the Motor would run for a set time before stopping instead, possibly by using an RC Network or another 555 Timer circuit.

Anyone with any advice on how to approach or achieve the result i'm looking for would be greatly appreciated, or advice on reasonably priced user friendly microcontrollers and how to get them to run a motor.
 

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Why not install another switching mechanism at the front to stop the motor when its fully out ? In this way you will not need to use the optocouplers at all
 

Thread Starter

mackwhyte

Joined Jun 14, 2017
3
The optocouplers are being used for more than just the open/closing action, they are also a part of the disc detection circuit so they would have to stay regardless. I considered putting another switch but due to the number of moving parts it may prove more difficult than said. I am also trying to make as few physical changes to the drive as possible, I plan to create a PCB with the circuit to install inside the drive so the drive will look standard and can easily be put back to its factory configuration as it is quite a rare drive. Like i said i already have a partially working solution, just integrating the limits is causing difficulty! who would have thought a couple of switches could cause such nightmares!

Thanks for the input anyway!
 

Thread Starter

mackwhyte

Joined Jun 14, 2017
3
Figured it out!
Took the plunge and bought an arduino nano, got 3 for 8 quid!

From there I taught myself the basics and created a Truth Table, instead of writing a high or low i wrote what i wanted to happen.
This left me 4 actions from the 16 possible combinations;
Load (Loads Mechanism,Simple!)
Eject (Ejects Disc)
reset mechanism (Ejects mechanism if it somehow manages to load without disc)
Blink (Blinks an LED if you attempt to eject Disc when there is no disc present)

After that created 4 karnaugh maps and used boolean logic checked the inputs.
Once the code was crested I tested it, ironed out any issues and fine tuned the program.
The program works perfectly using tact switches to simulate the optocouplers.

Now the problem is getting the optocouplers to sense! on breadboard with the Ir led powered at 1.2v 20mA i cant get the coupler to switch.
If i connect the collector to the 5v supply it shorts the board? but when i connect through a resistor it is fine. when a metallic object is passed by the sensor it flickers slightly so im going to try connecting the output to a transistor to see if that will fix the issue!
I'm going to try using a transistor
 

crutschow

Joined Mar 14, 2008
28,503
Now the problem is getting the optocouplers to sense! on breadboard with the Ir led powered at 1.2v 20mA i cant get the coupler to switch.
If i connect the collector to the 5v supply it shorts the board? but when i connect through a resistor it is fine. when a metallic object is passed by the sensor it flickers slightly so im going to try connecting the output to a transistor to see if that will fix the issue!
I'm going to try using a transistor
If you post a schematic of what you have, we perhaps could help.
 
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