I am a beginner with electronics and this is my first non-trivial soldering job.
I have a project where I wish to control the focus and shutter of my digital camera through dedicated shutter port. Camera wakes up when one cable (focus) is connected to the ground, and takes an image when the second cable (shutter) is connected to the ground.
When I made a first version on a breadboard directly connected to Arduino Uno, it seemed to work ok.
I wished to make project more permanent, and as the project also needs to use a motor, I chose to use the perfboard on the Adafruit Motor Shield v2.3. (There was no motor or external power connected to the motor shield at this time.)
When I had soldered everything, and connected the Uno w/motor shield to USB, everything was OK. I was able to blink the LEDs with the following test software.
When I connected it to my digital camera shutter port, camera seemed to awake immediately, which indicated to me that something was wrong. I disconnected the USB and took the board to a different room for inspection. When I separated the Arduino and motor shield, and laid the board on the table, it seemed like some smoke came out, although the board was no longer connected to power. I had disconnected it perhaps 1-2 minutes before.
I found a short circuit on the camera side of the optocoupler I had not found before. The problem place was in the connection from the camera to the board. The cables I use to connect to the camera has copper sheathed cable that I had difficulty both stripping with wire strippers, as well as connecting to the board. I ended up soldering the cables to 1 + 2 standard Arduino headers, and then soldering the headers on the perfboard.
The 2 header set was short circuiting. Because the camera is separated from the Arduino with optocouplers, the short circuit on the camera should just cause camera to constantly focus/take pictures, but in my understanding it should not have burned the Arduino or motor shield.
When I connected the Arduino + motor shield to USB after fixing the short circuit, the shield was not working at all anymore. My computer gave an indication that the device was drawing too much power out. I removed the motor shield from the Arduino and connected it to my computer, and very cursory test indicates that Arduino itself seems to be OK.
So before I burn a second motor shield I think I need some help:
(1) Are there some problems in my schematic? Or in my soldering? How is it possible that the motor shield burned?
(2) Do you recommend that I skip using the perfboard on the motor shield? It seems soldering by hand so close to the circuits on the motor shield is quite difficult for me and not a beginner thing to do at all.
(3) Any other practical advice? It seems it would have been wiser to use a connector between the camera cable and the motor shield. PCB header connector, screw terminal or something else?
I learned quite a few things when soldering this thing. For example, it seems like it was a bad idea to connect to the ground in the bottom part of the Arduino, because the wire goes exactly over the ground on the camera side, and it was difficult to solder it and this is perhaps one part where I messed things up.
Here is the Fritzing of how it should look like (the only change being that I used 4N26 instead of 4N25 as in the image) and images how it looks like.
