Sunday, March 15, 2015

The New Timelapse Slider - the Electronics

This was the hardest part for me. The previous slider had just constantly turning 1,5m long screw to drive the trolley, no integration with camera shutter. And had a hard limitation to approximately 2 hours of trolley slide.
So this time it is different: the device should operate in shoot-move-shoot style. So it needs a special driver that will manage the shutter actuations and synchronized trolley movements.

After some weeks of testing and development based on Arduino Uno R3 board

I have constructed a driver that includes:
- 16x2 characters LCD display (WH1602B, compatible with HD77480) + PCF8574 + 3 operating buttons;
- voltage regulator L7812CV that assures constant 12V DC voltage delivery to the motor (from the 14-18V input);
- output to camera shutter (on the plate it is just a 10K resistor to the ground);
- 2-channel motor driver (only one channel is used in my case) L293DNE.

The almost finished electronics

The Failures and Obstacles

Everything was fine until the circuits were on the prototype board and I don't start final soldering.
The first "catastrophe" happened when I by an accident just touched some pins of LCD by 18V wires. So the first Arduino went dead. The lesson: be always extremely careful with not isolated cables!
The second accident was when I wanted to solder again L293DNE. This took too long, and I must have damaged circuits inside the chip .The result was the second dead Arduino board :-(
The lesson learned: solder dedicated bases, not the chips!
After this accident I just thrown away all the components and used brand new ones (except LCD).

The last issue occurred hen I soldered my circuits and then the LCD started going crazy short time  after the motor ran.

This is how I like it...

... and this is how I don't like it.

I assumed that this was caused by reverse electric noises from the motor and I was right. I soldered two capacitors between motor outputs and the ground. This helped instantly.
Finally the capacitors are not used, because in the third Arduino and third plate the phenomenon does not occur.

Here the final schematics:

Wednesday, March 11, 2015

The New Timelapse Slider - the Mechanics

As I have previously stated - the mechanics should be light and simple. I chose to build my timelapse slider around existing vieo sliders available on polish market. I picked a very simple, teflon-barings-based 80cm slider from Camrock.

I decided that the construction of the original product will be left untouched when my motorising set is attached finally. This is easy with Camrock, as it has predrilled holes on both ends.This made attachment of plates with axes easy. So I added:
- an aluminium box (or just square pipe profile) with attached 12V DC motor, 1.2Nm torque, 5.6 rot./min speed, like the one here
- a second end plate for the gearwheel
- a polyurethane belt, 6mm wide.
Motor wheel, opposit wheel and the belt are T2.5. The belt is open but attached to the bottom of the trolley with a Alu bracker, on which I cut crooves that fit the belt indents. The slider trolley is perfect in it size for my application; the recess below it perfectly fits the blt width and the whole layout (21mm x 11mm).

What I am still missing in the mechanical part is to round the end plate to have smooth corners.
The finished setup is really lightweight:

Thursday, March 5, 2015

Completely redesigned timelapse slider is on the way

My previous timelapse motorised slider was sold some months ago. It was strong and sturdy, but not very portable and had some other limitations like that could not travel for more than 2hrs, could not move in a manner "shoot-move-shoot" and some minor others.
So I have addressed now all these issues. The preconditions are:
1. Portability
2. Shoot-move-shoot capabilities
3. Simplicity - the driver and power source in one package
4. Easy access to power source - just AA batteries for all (driver and motor)
5. Low power consumption - usage of DC motor

And here it is!
Prototyped electronics:

and finished mechanics:

As you can see the driver is based on popular Adruino Uno R3 which gives me great flexibility in programming of the slider behaviour.

I want to share all the details of the device so the story will continue. Subscribe to follow!