Kodak Slide Projector Scanner

Yesterday I was able to do my first working test and you can see the results in the video below:

After running it for a while, I realized that the transformer was getting very hot. I took out the original cylindrical spinning fan thinking it wasn’t necessary anymore and it looks like I was wrong.  Because I’ve now used that area where the fan was for power input, I’ll have to install a new fan in another location. I’ll likely use a PC computer fan to keep things cool.

Another thing noticed was that the mechanical arm that drops the slide into place seems to be sticking before it bottoms out. The result is the slide isn’t in proper position when the photo is taken. To fix this, I’ll glue a small chunk of steel weight the leaver and let gravity do it’s thing.

I’m still waiting for a new lens for the LED, but I have now 2 of the original glass lens I can use in the meantime. I’m also using 2 transparent diffuser sheets to even out the back lighting. I’m hoping that with a better lens, I’ll only need the one.

Lastly, the inside of this thing is a huge mess of wires and ac-dc, dc-dc power converters. I’m going to finally replace all that with a small custom PCB that rectifies and steps down the voltage directly off the many coils on the original transformer.

I used the power connection and switch from a dead computer power supply to convert the projectors black plastic vent/remote plug area to the power input area.

Behind that, I connected up a laptop power charger that outputs 19v DC 3amp and connects from AC plug. This laptop charger will be my source for clean DC power that will drive the LED driver and later drive the Arduino microcontroller after being stepped down to 5v.

The LED needs some form of active cooling to keep it from burning up. I’m using a copper heatsink from a an old computer GPU and a 24v fan. The LED has thermal paste where it contacts the copper heatsink and is held in place with some bits of clear plastic screwed into place. The fan is a bit overkill in size but because I’m powering it from the same 14v-15v LED driver it’ll spin slow and not add to the vibrations. I have the fan in the pull config that way it'll  not blow dust out of the scanner. 

The LED driver is an adjustable CC CV step down buck converter. On it’s input is around 19v and I’ll be bringing it down to between 14v-15v to drive the LED.

I’ve decided to disassemble the light assembly from the projector and keep only the glass lens.  

Doing some initial tests you can see that the LED produces a very uniform beam.  You can see how the light beam shape changes as the distance from the LED to the lens changes.

I have some plastic diffuser sheets out of a dead computer LCD screen I might do some tests with to get an even more consistent back lighting, but It might not be necessary and could possibly reduce the light quality if it absorbs specific wavelengths of light. More testing will be necessary.

Next thing on my list of things to do will be trying to isolate the AC motor vibrations and making some kind of housing to hold the LED module and glass lens in place.

After ripping out everything off the plastic frame, it's time to start installing the necessary components and testing that they work. 

Rewiring the motor, circuit board and mechanical assembly together, I found that the original grease was solidifying and sticking causing the slide loading mechanism to jam. I had to clean and decrease the assembly and than applied some silicone oil and Teflon grease to get it running smooth again.

One thing I’ve realized after powering it was how much vibration the AC motor makes. The AC motor sits on rubber grommets and possibly over time, they’ve hardened. Maybe not. But the vibrations are enough that is could be visible when taking the side photo. I have a sheet of Sorbothane material that I plan on replacing those grommets with and hopefully that'll reduce the vibrations enough.

Once I wire in an ICE power cord and switch, I’ll wire in the relay’s that’ll be driving the mechanical actions. I'll be using relays to drive the projector because I want to keep the circuits of the DSLR camera, microcontroller, and projector isolated. The projector’s mechanical slide loading mechanism is slow enough that the slight delay from the relays will not be an issue. 

The relay board I’m using in particular uses 4x DSRD-05VDC non-latching relays that'll runs from 5V. This board also has optocoupler between the logic and is a nice small package.

I’m still waiting on an LED power driver board so installing that will take some time. The plan for the LED is to mount it onto the backside of a CPU heatsink with a small fan to keep it cool.

The LCD board has some push buttons and the Hitachi HD44780 LCD and packaged as an Arduino shield that snaps into the Arduino micro-controller below it.

Originally I was making a custom board to drive the camera, projector, led driver, etc.. but I'm scrapping that because rewiring the projector is difficult enough and we can use off the shelf circuit boards that will do everything needed.  This custom board is great, because it's created exactly for this projector and camera's purpose, but would be difficult and time consuming for someone else to reproduce this project. 

I’ll keep this post light on text and more on visuals.

Time to open up the projector but we'll need a bigger cleaner table!

That's better. This space will do. 

This is the inside of the projector with the front focusing mechanism taken out.

We're only going to need a couple parts, so it's best to tear down the projector to it's shell.

We'll keep the lamp module, but remove the mirror and the lamp. We will be replacing it with an LED  and shine it directly into magnifying lens.

The mechanism assembly is used to load slides and advance the carousel. It'll need some cleaning up!

The motor drives the mechanism assembly and powers other components. This part will be necessary and we'll tap into it to power the microcontroller, and LED driver. 

The circuit board looks simple and sparse. All we need is to power forward and reverse on the mechanism assembly's solenoid, so we might not need it at all.

The projector that I will be sacrificing has arrived and It is the Kodak Ektagraphic III AM projector. This one in particular has a bad focusing motor (won’t matter) and mechanically loads slides flawlessly. The slide collection is contained in both Kodak carousels and metal slide file boxes so I will use both carousels and stack loaders to churn through them.

An idea I might look into implementing is an electronically controlled air compression system to blow off dust for the currently loaded slide. This would involve a small air tank compression system and an electronically actuated compressor head driven by the microcontroller. With this setup loaded slides get cleaned with compressed air just before the photo gets taken.

I will get the rest of the system working and leave this as a possible addition after.

Today I have miniaturized the electronics originally running on an Arduino mega onto an Arduino pro micro. I would like to use something small like the pro micro or mini in the final build instead of full size arduinos and shields. Looking at the necessary number of input and outputs the scanner needs, the pro micro should do the job fine.

I’m also looking into the idea of using interrupts to delay triggering the shooting of the photo.

The idea would be that once the slide is loaded, there will be a short delay to settle any mechanical vibrations before taking the photo. This should work out much better than waiting for a period of time and making the assumption that the projector is ready for a photo to be taken.

Another added benefit of this will be that I’ll know if a slide is loaded or not. The system could go into standby mode as it waits for more slides to be loaded only taking a photo when an actual slide is in position.

Other than that, I am mostly waiting for various hardware to arrive for this project so in the meantime, I’ve been writing arduino code and prototyping the electronics.

If you’ve got any ideas that this project might benefit from, please post your ideas!