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Thread: Heathkit Darkroom timer revealed glory!

  1. #51

    Join Date
    Feb 2013
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    315

    Re: Heathkit Darkroom timer revealed glory!

    Randy, I don't know who built that timer, but I'd guess he's OCD! I've seen factory made stuff that wasn't that neatly made!

  2. #52

    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by Bob Salomon View Post
    It also needs to run on 50hz down there or times will be 20% off.
    Yep Bob, you are right. I eventually received the manual, & it didn't take long to convert the transformer to run on 240V, but the 50hz / 60hz issue is real. Like you said, it is running about 20% slow.

    Is there any known work a rounds for this?

  3. #53

    Join Date
    Dec 2014
    Location
    Iowa City, Iowa
    Posts
    1,471

    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by Snoopy-16 View Post
    Yep Bob, you are right. I eventually received the manual, & it didn't take long to convert the transformer to run on 240V, but the 50hz / 60hz issue is real. Like you said, it is running about 20% slow.

    Is there any known work a rounds for this?
    Money

  4. #54

    Join Date
    Dec 2011
    Location
    Sydney, 34 degrees south
    Posts
    35

    Re: Heathkit Darkroom timer revealed glory!

    I think the only easy way to get a 60Hz AC supply is with an inverter. I don't know how well that would work; your timer probably expects a clean 60Hz input, and an inverter might generate some noise.

  5. #55

    Join Date
    Oct 2006
    Location
    New Jersey
    Posts
    1,392

    Re: Heathkit Darkroom timer revealed glory!

    I’m sure I am stating the obvious, but why don’t you re-mark the dials with times adjusted for the 20% difference, so 1 minute would be 1:12 etc. what you need for printing is consistency, not timing in one-second or one-minute intervals.

  6. #56

    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by Tin Can View Post
    Would you confirm which holes are which adjustment?

    Just for the 'permanent record'.

    Thanks
    Could someone answer this question, please?

  7. #57

    Re: Heathkit Darkroom timer revealed glory!

    a device that has proven itself from the best side not a few times, proven by time and experience. At the present time, in fact, everything has to be rebuilt by yourself, adding your own components.
    Last edited by LeonardDowd; 20-Dec-2020 at 05:20.

  8. #58

    Join Date
    Aug 2004
    Location
    NYC
    Posts
    583

    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by Tin Can View Post
    Would you confirm which holes are which adjustment?

    Just for the 'permanent record'.

    Thanks

    its in the manual.....

    https://www.vintage-radio.info/heathkit/

    its a pdf as PT-15

    scroll down past the oscilloscopes.

  9. #59

    Re: Heathkit Darkroom timer revealed glory!

    Thank you.

  10. #60

    Join Date
    Jun 2013
    Posts
    157

    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by Snoopy-16 View Post
    I have just bought the PT1500 Heathkit darkroom timer. It was previously used in the USA. As I’m in Australia, I need to convert it to run on 240V. I have found a manual on EBay UK & the seller has just posted it, but has just told me it’s going to take 12 weeks to be delivered!
    Does anyone have the build manual & could post / email the relevant section on setting the transformer to switch from 120V to 240V that you would not mind sharing, so that I can get this timer working now?
    Thanks in advance 😊
    It also needs to run on 50hz down there or times will be 20% off.
    Looked at schematic posted by Paul Ron (for the PT-15) and there is nothing there that depends on the mains frequency. Indeed, the specs section explicitly states 50/60cps.
    Click image for larger version. 

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    But in case your PT-1500 is significantly different from the PT-15 and does depend on mains frequency, what is the real drawback of running 20% slow, if used as an enlarger timer? You do test strips, anyway, right? So why not time all your exposures in pseudo-seconds? As long as the times are consistent between test strip and actual exposure, you should be doing fine. A 60Hz inverter would be overkill.
    Attached Thumbnails Attached Thumbnails Capture d’écran 2020-12-21 171602.png  

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