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  1. #1
    holmburgers's Avatar
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    Timer w/ Noise Signals - Something to hear in the dark... idea for modifying GraLab

    Ok, so I also use my classic Gralab enlarger timer when I'm developing film, sometimes in open trays, which means several minutes in complete darkness.

    The glow in the dark is great and all, but it just doesn't cut it and I'm finding myself leaving the tray and putting my head 6 inches from the damn thing just to see when my 30 second agitations should commence!

    Grrr...

    I thought, golly gee whillikers, if I had some kind of simple audible signal my troubles would be over. And I don't mean a metronome that beeps on the second, which would drive me all the more bonkers.

    So my question is, has there ever been a count-down timer that accomodates some kind of intermittent signal?

    However, I think I've got a better idea...

    I'd like to attach a dangling bell at the top, right above 12 o'clock, so that when the second hand passes it will ring it. Conversely, on the bottom, I'd like to have some thin piece of metal projecting upwards so that it will be "plucked" as the second hand passes. (kinda like a jaw harp)

    I've attached a piece of Art (note the capital A) to better demonstrate this.

    Whaddya think?

    Any good ideas for materials to do this? I can probably throw something together fairly easily, but specifically I'm wondering what a good metal might be for the all important boing, and I need to make sure it doesn't halt the movement of the hand.
    Attached Thumbnails Attached Thumbnails Gralab MOD.JPG  

  2. #2
    Mike Wilde's Avatar
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    I went the electronic route. I was gifted a little timer by the son of a photographer who had died off.
    I would have loved to meet him. He did lots of colur printing at home in the 70's. Tray heater control DIY, Light measuring device, tray temperature electronic thermometer, etc.

    His timer generates a relay closure and a little chirp from a sonalert buzzer every 5, 10, 20, 40, 80 seconds, or a variable number of seconds. I have set the variable setting to thirty seconds and power it from the enlarger socket of the gralab 300. It takes 45seconds to start, which is fine, because I agitate continuosly for the first 15 seconds anyway.

    It is built around a 555 timer IC.
    my real name, imagine that.

  3. #3
    holmburgers's Avatar
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    Interesting mike, thanks for the contribution.

    I'm not so sophisticated when it comes to electronics. I'm more of a "sticks and stones" guy... caveman if you will.

  4. #4
    MattKing's Avatar
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    Tape or digital recorders are great sources for audio timing cycles, and you can add music if you like.

    Kind of boring to record though.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  5. #5
    Rick A's Avatar
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    I understand some folks use metronomes for developing.
    Rick A
    Argentum aevum
    BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"

  6. #6

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    I think it's an interesting idea. Though something that would make a loud enough noise might well interrupt the hands.
    If you wanted to get into a little bit of electronics, you could possibly wire a couple of reed switches to the buzzer circuit so that the hand just brushes the switch and it would give a short little "beep" when switch closes then opens. It would be easier to implement, I think, if you weren't going to use the buzzer for anything else. (I don't ever use the buzzer on mine, much too loud and annoying).

    Another possiblity might be using light, tape an LED throwie to the second hand; http://www.instructables.com/id/LED-Throwies/

  7. #7
    ic-racer's Avatar
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    Click image for larger version. 

Name:	unicolor_timer_10_benson_midtown_7817752.jpg 
Views:	12 
Size:	8.4 KB 
ID:	44701The simple "jingle bell" timer is kind of like that, but it won't keep running after the jingle, though. It looks like it could be easily modified to keep running.

  8. #8
    polyglot's Avatar
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    I like the bell idea for low-tech.

    If you wanted to get all fancy you could put a reed switch (they close when there's a magnet nearby, mouser at least sells them as small as 7mm) or three at critical places (with blutack!) on the face with a little speck of NdFeB magnet on the timer arm. Relay will be closed for a couple of seconds while the hand is adjacent, and that can be used to turn on a little 5V piezo beeper. And then of course you have a monstrosity of wiring.

  9. #9
    Rick A's Avatar
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    That jingle bell timer reminded me of a similar one I had years ago. I forget who made it, but it had a way to set bump stops on the face to trip a bell at predetermined times in a sequence. You set the total time by turning the dial, and the trip fingers activated a dinger as they passed. It was explicitly made for film processing.
    Rick A
    Argentum aevum
    BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"

  10. #10

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    What about the RH Designs ProcessMaster II? It times down, compensates for temperature fluctuation, it's programable and beeps every 30 seconds.

    http://www.rhdesigns.co.uk/darkroom/...essmaster.html

    I use it for film processing in the daylight, but the display can be dimmed for use in the dark.

    Nick

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