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  1. #21
    polyglot's Avatar
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    Powerswitchtail is a good option, especially for people without the proper training for dealing with mains voltage. And you can certainly buy most of the bits from sparkfun, though they seem a little expensive to me for the generic bits and pieces. I bought most of my stuff from eBay.

    The device is powered from the mains, since it is switching mains. No need for batteries etc as it saves all of its settings to internal EEPROM. The simplest power supply you can have for it would be an iPhone charger ($5 on eBay) which gives you 5V 500mA on a USB port; everything in the timer can be powered through the Arduino's USB port. You don't need a PC to use it as long as you don't want to save more than 7 stored programs; the PC is needed only for backing up your stored exposure programs.

    While I disagree with some of Nicholas' pricing estimates (I just bought most of those parts and the prices I listed are what I paid), there is of course a sliding scale of quality and you can literally spend as much as you want when building this. For sure I am not using a custom wooden box, I'm using a black ABS prototype box or maybe a diecast one if I'm feeling fancy. And yes, I am making good use of my huge electronics "junquebox"

    In terms of value proposition vs products like Nicholas', there is only value in using this if you know where to buy cheap parts, don't value your time, have the necessary skills+tools on hand and/or want to be able to hack your timer to add new functionality. If you want an off-the-shelf, supported thing that Just Works you should go buy a finished product. Nicholas' point about no profit margin with a sale price of $259 should tell you why I'm not selling these things as finished products or kits; it's a labour of love for me too and I choose to make my IP available to those who want to replicate the laborious part.

    The interesting thing about the GPL is that commercial operations like Darkroom Automations can take my published source code and sell you this very product in a fancy wooden box with fancy keypads etc at whatever price-point they desire; the only hook is that they must publish the source code. If it runs mine unmodified then they can just point to mine but if there are any improvements, they must publish those improvements so that the rest of us can make use of them.

  2. #22

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    I value my time and money. However, value of my FUN often wins.... (where did that $100 go?)
    Develop, stop, fix.... wait.... where's my film?

  3. #23
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    And it is released for your edification, commentary and feedback.

    Sorry no pics yet as my red LCD hasn't arrived so all the development was with a big blue one. Once I get back from holidays I'll finish the assembly and shoot some video of it in action - if you're quick with the soldering iron, it's possible you could get to use this to print before I do!

  4. #24

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    Thank you.

  5. #25
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    Web page has been updated with embedded video showing the user interface, or watch it here.

  6. #26
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    Thanks--this is great. I need to digest this, but some of us that haven't worked with an Arduino may need some remedial help.

  7. #27
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    I am frankly puzzled.
    I know what an f/stop is...the numerical value which represents the denominator in the ratio of the diameter of the aperture to the FL of the lens.
    I know what a timer is.

    How the heck do you TIME an f/stop?!?!?!

  8. #28

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    Quote Originally Posted by wiltw View Post
    How the heck do you TIME an f/stop?!?!?!
    The OP is speaking of his stops with reference to a base exposure. What he calls f/stops should probably be called simply "stops" so that they are divorced from apertures.

    One stop more light is accomplished by twice as much time. Two stops more light requires four times as much time. Thus it is a power (exponential) function. Logs are the opposite of exponents.

    Half a stop more light is had by multiplying time by 1.414 (the square root of 2), since you can take your base time, multiply by 1.414 to get a half stop more, and multiply that by 1.414 to get yet another half stop, a whole stop from the base time. By application of logarithms you can get any intermediate stop in terms of time from the base time.

  9. #29
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    Quote Originally Posted by wiltw View Post
    How the heck do you TIME an f/stop?!?!?!
    It's a very bad name for a timer.

    The method got it's name before there were such things as f-stop timers. The method uses exposure times in seconds that follow the f-stop numbering sequence: 1.0, 1.4, 2.0, 2.8, 4.0, 5.6 seconds ... When used as times each is 1/2 a stop more exposure.

    This timer and the Darkroom Automation system use decimal stops. 1.0 stops = 2.00 seconds; 1.5 stops = 2.83 seconds; 2.0 stops = 4.00 seconds ...
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  10. #30
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    Quote Originally Posted by Nicholas Lindan View Post
    It's a very bad name for a timer.

    The method got it's name before there were such things as f-stop timers. The method uses exposure times in seconds that follow the f-stop numbering sequence: 1.0, 1.4, 2.0, 2.8, 4.0, 5.6 seconds ... When used as times each is 1/2 a stop more exposure.

    This timer and the Darkroom Automation system use decimal stops. 1.0 stops = 2.00 seconds; 1.5 stops = 2.83 seconds; 2.0 stops = 4.00 seconds ...
    Indeed. It should be called a logarithmic timer or similar. Here is an article on the method.

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