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  1. #11
    nicholai's Avatar
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    LED produce much more light with way less energy, and my experience tells i can easily touch them while they have been running for hours.
    Nicholai Nissen
    Kolding, Denmark
    nicholainissen@gmail.com

  2. #12
    Steve Smith's Avatar
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    The company I work for makes some of the flat, flexible light panels shown on this company's website:

    http://designledproducts.com/

    One day I intend to try out something similar in my 5x4 enlarger.

    And they don't require heatsinks.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  3. #13

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    I use LED's in my home office, the heat from them is significantly less than the tungsten bulbs they replaced, it's very noticeable in the summertime.
    The oldest one is about 4 years old now, and they are generally on for 15 - 18 hours/day * 7.

    They do have a slight afterglow, for maybe 15 seconds after the power is off.

  4. #14
    David Brown's Avatar
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    Quote Originally Posted by David Brown View Post
    do LEDs produce (less) heat (than) tungsten,
    Yes, if I understand correctly.

    Quote Originally Posted by David Brown View Post
    and do they damage relay circuits?
    Maybe, see below:

    Quote Originally Posted by David Brown View Post
    Does it make a difference if the relays are mechanical or electronic?
    Thanks, everyone. This has been interesting and informative. Allow me to narrow the follow-up question:

    Regarding the relays: I doubt much of anything would be damaged in an old TIme-O-Lite enlarger timer. It's basically the same as a light switch. However, what I would be concerned about is my RH Designs Stop Clock (APUG sponsor alert). I don't want to fry its electronics with the wrong type of bulb, if that's possible. I am going to email the company and ask specifically, but it would be interesting to hear actual field experience, if there is any.

  5. #15

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    If the LEDs are within the current rating of the timer it will be fine.

  6. #16
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    Quote Originally Posted by David Brown View Post
    It's basically the same as a light switch. However, what I would be concerned about is my RH Designs Stop Clock (APUG sponsor alert). I don't want to fry its electronics with the wrong type of bulb, if that's possible. I am going to email the company and ask specifically, but it would be interesting to hear actual field experience, if there is any.
    Does the Stop Clock make a clicking noise (could be extremely quiet) when it turns on and off or is it completely silent? If it clicks, it has a mechanical relay and it will be fine. If it's silent, it's probably a triac.

    While a triac can in theory be damaged by attaching an LED switching supply to it, that's highly unlikely and I would not expect RHD to cheap out on the protection circuitry. Surviving a globe-blow event on an enlarger with transformer is far more stressful to a triac than an LED supply. More likely though is that the LED just doesn't light, not that any damage occurs.

    If you have the ultimate in paranoia then you can buy an electromechanical mains relay, i.e. one with a 240V (or 115V) coil and mechanical contacts, e.g. ebay 390510321612 or similar. Let the timer switch the relay on, which will switch your load on - that will work, guaranteed, and it will not damage the timer or the LEDs. I don't reckon it's necessary, but wait to hear back from RHD before taking my advice on their product that I actually know nothing of the specific internals

  7. #17
    David Brown's Avatar
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    Quote Originally Posted by polyglot View Post
    I don't reckon it's necessary, but wait to hear back from RHD before taking my advice on their product that I actually know nothing of the specific internals
    Waiting patiently ...

  8. #18
    polyglot's Avatar
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    Does it make a little click or tink noise?

  9. #19
    Steve Smith's Avatar
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    Quote Originally Posted by polyglot View Post
    Does the Stop Clock make a clicking noise (could be extremely quiet) when it turns on and off or is it completely silent? If it clicks, it has a mechanical relay and it will be fine. If it's silent, it's probably a triac.
    I'm fairly sure it's a relay. In a thread on another forum, I raised the issue of using a solid state relay module for a timer and Richard of RH Designs stated that he uses mechanical relays.

    It was a few years ago and I don't know if that is the case with all of his products but I suspect that it is.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  10. #20
    polyglot's Avatar
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    Quote Originally Posted by Steve Smith View Post
    I'm fairly sure it's a relay. In a thread on another forum, I raised the issue of using a solid state relay module for a timer and Richard of RH Designs stated that he uses mechanical relays.

    It was a few years ago and I don't know if that is the case with all of his products but I suspect that it is.
    Presuming that to be true, there will be zero issues using a Stop Clock with an LED enlarger and/or safelights.

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