Arduino based diy f-stop timer

[bernard_L]

Hi, Elia,
Your device looks great. Looks you gave some careful thought to the ergonomy. I'm tempted to build a couple (for myself and as a present). I'd like to buy the PCB from you (if you still have some), and the other components commercially. To put my questions below in context, I have a fair experience in electronics (discrete components, op-amps, 74XX digital) but none in microcontrollers.

• Several drawings are available on your site only as low-res images, not usable, e.g.:
  • front panel drill template, on https://eliadarkroom.wordpress.com/hardware-references/
  • schematic on https://eliadarkroom.wordpress.com/monkito-schematics/ or
    https://i2.wp.com/eliadarkroom.files.wordpress.com/2018/01/monkito_arduino_pcb.jpg?ssl=1&w=450
• I'm confused about the versions; if I embark into this project, I must make sure that the Arduino, the PCB, the code, and the user manual all match together, and match with what I hope/expect to obtain.
  In: /monkito-schematics/ you refer to the schematic as "latest version". That is confusing: someday there may be a revision and it will no longer be "latest version". Why not give numbers like PCB_1.5, or whatever, and provide a compatibility table between software revisions and PCB versions, to take care of issues such as: "Relay pin is now 7 instead of 11. The schematics has not been updated accordingly." An up-to-date schematic is needed to wire the components properly.

So, assuming I would like a timer for ordinary, single lamp, enlarger head:

• What PCB version? Can you sell me two? If not, can you make available the Gerber files?
  
• What code version?

Again, congratulations for your work, and thanks for making it available. And, yes, documentation is not the most rewarding part of a project...

 

[Elias]

Hi Bernard,
thank you for your positive comments.
About the images, wordpress does resize/compress images oddly. I will have a look to try to figure out a solution to have the drawings and schematics displayed properly. In the meanwhile, yes I can provide the original images and Gerber files to anyone upon PM request.

About the PCB, the last version is the best as it embarks everything needed and allows much better connections to the Arduino board. Some PCB are still available, please PM to arrange shipment.

About the versions, I am sorry about the confusion. You are perfectly right, I am postponing my wordpress site overhaul since weeks (I should say months now...) as have been working on the LED head control and I changed the code various times according to the timing strategy for LEDs and contrast control. The code is still working for incandescent bulbs (through relay shield) and I updated the timer code which now uses millis() instead of delay() which allowed me to write a much cleaner code and correct timing shift by code and reach a constant precision of less than 1 millisecond. The next step would be the website overhaul to include latest developments and versions history.

For the community, please allow some days for website overhauling and latest code publication as it still needs some cleaning.

Bernard, thank you to remind me to to remain up-to-date !

 

[bernard_L]

Elias,

Thank you for the prompt reply. And for taking my criticism in a constructive way. In the meantime, I thought more about this, and realized that there should be nothing wrong for me with the VC version that drives (presumably) green/blue LEDs, even if I don't (yet) have such a light source; all I need to do is pretend I use a fixed grade 2 (say) and connect to the output for (say) the green LEDs. I should probably replace my incandescent bulb with a white LED to have good accuracy of effective lighting times.

Something that would be nice in the VC version (maybe it's there, but haven't seen it reading through available docs). Somewhere in permanent memory a table, that would require a one-time calibration by the user, ensuring constant sensitivity (at D=0.6) across contrast settings, with suitable adjustments of the Green Blue LED intensities. Several tables, actually if one uses different papers.

Best regards,
Bernard