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  1. #21

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    I forgot to add that you can have a NE555 timer made to progress in geometrical instead of linear. For example you can have times like 1.4, 2.8, 4, 5.6, 8, 11, 16 ... seconds... If you add a switch to divide the basic interval in half it could be useful.

  2. #22

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    Hi Al thanks for the replies.

    I think i am going to go ahead and build one anyway..

    HEre are m thought on compliance. That's the reason I would use a simple plug pack for input.

    As for the switch gear. I will put all the wiring and tracks in place for those who want to connect an enlarger to it.

    As a bsic f stop timer.. it it beeps and flashes at the right moment. I don't think it's that difficult to reach a power switch and hit the on or off switch.

    Those who need the automation can go buy a relay, open up the box and solder it in. In fact to sidestep those compliance issues, we can go all the way up to relay. that switches. It's then up to the user to open up and wire it up to the enlarger . I think that should solve the problem. A terminal block will do. I am sure if I put up a web site , there will be plenty of volunteers who will do a "howto wire up enlarger" safely..

    This is after all for a hobby.. labour of love...

    It can even be powered by 4 AA rechargeables..

    Board - I can really roll them off quite inexpensively. I know a PCB manufacturer who does work for large contracts that i dish out. So he can get some done for me mates rates.. another benefit to the community.

    I'll get a recalibrate on the cost of components and soldering up and get back to you guys.. Maybe $50.00 at the most .

    At what price will you guys buy a Simple F Stop timer ?

    $25
    $35
    $45
    $50


    Give me a vote please..

  3. #23

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    Refining the specs as we speak:

    Device is battery powered 4 AA's or 5 - 12 Volts DC plug pack (solves those pesky CE C-tick, FCC Part 15 Electrical regulations)

    Always counts up from 0 to 64 seconds.
    On activation beep 3 times flash led 3 times then start counting up
    At 0 seconds trigger 12Volts/Relay switch ( user implemented after purchase) Switched Terminal Block.
    Beep at each major f stop , e.g. 4 seconds 8s, 16 s 32s 64s.
    Provison to beep also at 1/3 stops between 8 seconds to 64 seconds.
    e.g. count up to 8 seconds and beep at each 1/3 stop.
    ability to set range for beeps. - helps with making test strips.
    at end of counting period trigger 1 long beep and simultaneously trigger the relay to switch the enlarger off. (user to implement)



    I can draw a picture of this simple device. But don't know where to post it.

    The target price should be around $25 -$35.

    Shoud use a simple 5V USB plug pack or 12 Volts plug pack.

    1) Make up kits for those who want to solder them up
    2) Make up finished items - small run of 50 units for those who don't wish to bother wiht the above.
    3) Offer schematics and board layout to the APUG members and anyone on the web for that matter.
    5) Wite up the software to control the timer- offer binary and source code to anyone.
    6) Get a repository going for those who want to offer modified code based on the board layout.

    I'll definitely go with SMD components onlyto minimise labour..

    What do you guys think..

    Do you need a simple F stop timer that beeps and lights a red led at each major F stop?

    I'll definitely need one to help me wiht my test strips...

    At what price will you guys buy a Simple F Stop timer ?

    $25
    $35
    $45
    $50


    Give me a vote please..

    Please let me know your thoughts.

    I'm going to go to prototype soon, I really need such a timer myself. Will keep you guys posted.

    Anybody know how to post photos and schematics on this site ?
    Thanks

    I'm in sydney for those who need to know.

  4. #24

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    Images can be attached to posts - there's a button on the toolbar for it.

    Good luck!

    p.s. I'd be inclined to include some seven segment LEDs to display the time remaining, and I'd make it count down rather that up, but it's up to you!

    Oh, and I'm happy to help troubleshoot for you if you run into any problems...

  5. #25
    paul_c5x4's Avatar
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    Quote Originally Posted by kittyhawk88 View Post
    Refining the specs as we speak:

    Always counts up from 0 to 64 seconds.
    For lith printing and alt processes, 64 seconds is going to be limiting. I have used exposures of five minutes, and I suspect some are going even longer with UV.

  6. #26

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    I've built a simple web page to follow the developments of this timer . Here's the link.

    I've posted on it a jpg of the timer interface..

    http://www.geocities.ws/fstoptimer/

  7. #27
    olleorama's Avatar
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    Good work kittyhawk. I want an outlet for a foot control to start the thing. Or for focus. Can that be incorporated?

  8. #28

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    Hi Olleorama,
    a foot switch is really quite simple to incorporate. As I see it. The timer switching section has only 2 modes. Either safelight on and enlarger off or enlarger on safelight off. So the switching section just needs to have 2 way relay. I think a double pole double throw.. I need to think this one out. However a dual relay would be a better bet as someone somewhere will want to focus with the safelight on.

    I'll add that to the requirements.

    I will build the relays and terminal blocks into the enlarger but will leave the user to onnect it up. The eletrical regulations problem.. I don't have the moeny to get this pass regulatory requirements. So it's up to the user to wire those switches in country dependant etc. I'm working on a $39.00 USD target so that it's affordable. We want people to convert to f stop timing no discourage them.

    I'll add the option into the website.

  9. #29

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    Updated Timer Interface

    Worked out how to post pictures.

    Here's the link if it does not work.
    http://www.geocities.ws/fstoptimer/
    I've started on the code design.
    Have chosen to implement this design with PIC Microcontroller with an external quartz oscillator for accuracy to +- 0.001 seconds.
    will implement a 6 volts switched relay output. you can use this to drive a relay.
    C1 and C2 are toggled on and off . So you can switch the dark room lights on or off.
    Focus lets you switch the enlarger on with no time limit
    Reset lets you start all over again
    Reset followed by > key lets you set time period
    Reset followed by > key then left key lets you set test strip mode

    Beep - sets beep off or on. When beep is off LEDs light to indicate time.
    Beep on - needs no explanation

    Start - starts the timer - Also slaved to footswitch.

    Footswitch - will use a standard 3.5mm jack

    9/12 volts input. Lets you use an external plug pack to power the unit instead of 4 AAs. Useful if using unit to drive external relays to power switch enlarger on or off and safelights on or off.

    Comments please..
    Attached Thumbnails Attached Thumbnails f stop timer.jpg  

  10. #30

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    Would anybody object if we added say $5.00 USD to the completed meter purchase price to donated to the running of APUG?
    Comments please , thanks.

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