chuck-finley

I'm probably a little late to the party, but is there any reason why you cut and soldered the black wire? Wouldn't it have been the easiest to just add the switch to red cable only?

Great instructable! The video is concise & well made, really enjoyed it!

I think I understand you now. If I would have made full use of the opto isolation (connecting the other GND / VCC Pins with a separate connection and removing the jumper) I shouldn't need to worry about the current limitations. I will definitely keep that in mind when I do my final design in an enclosure, thank you for your input!

Thank you for your positive feedback and your remarks! Yes probably I could leave the sensor module out, but then I would need to make a connection on my perfboard to get one of the connections to an analog pin and an output pin. Probably easier to just leave it that way since they ship with the modules anyway.Regarding the ULN2803 comment, I had a different circuit with a relay that fried one of my chips within a day. After adding the ULN no fried chip in a week now. For complete opto isolation I probably would need another power supply and then the current draw for the relay board would still exceed the chips rating, if I understood everything correctly. The ULN chips are pretty cheap. Thanks for pointing the issues out!

Thank you for your input. I actually used a standalone atmega chip but referred to an arduino in the instructable for the simplicity. I originally planned to combine the project with a sensor for day and nighttimes but found out that the lightning conditions in my hallway would not really allow me to sharply distinguish between the times I need the lamp to turn on or not by a photoresistor. I will probably extent the project with a solution to that that justifies the need of a controller of some kind in the future. This was one of my first projects with the arduino/atmega so I kind of missed the opportunity that I don't really need it. Good catch!

You do not need to remove the chip from the Arduino to program. You can build a minimal circuit on the breadboard for the chip (I think this would be required anyway) and upload the ISP program to the chip on the uno, and then program the chip via "upload using ISP". My chip sits so firmly on the uno, I was afraid to break it during removal, so I left it.

Neat project! I always wanted to learn morse code and I have most of the required parts lying around. This is a nice starting point to finally learn it.

Nice instructable! I like that you explained all the connections in such detail. On a side note, you can use code blocks in the formatting to embed the code a little better.