Countdown timer

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  • Countdown timer

    Some years ago I made this countdown timer for my air cleaner. I used an electromechanical spring-wound Intermatic 0-12 hour timer that I got on sale but they run about $23 now. I put it in a couple of electrical junction boxes and a power cord and used it to control my air filter/cleaner - I would set it on 4 to 8 hours and work in the shop and leave it running after I retired. I use another one to limit the time for older NiCd/NiMH chargers where they can get overcharged if you leave them on too long.

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    I upgraded to one of the new countdown timers.

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    You press the button to select which of 8 preset times you want.. 5 min, 10 min, 15 min, 20 min 30 min 1 Hr, 2 Hr, 4 hr. and off.
    Once you select one of the settings it turns on the outlet for that amount of time and then turns off.
    I plan to use this for glue guns and my wood branding iron because I'm always worried I might forget and leave it on. 20 minutes setting I think is ideal for those.

    These timers are only $11 on eBay and you can make the whole thing adding a plastic double-gang outlet box, a new style square duplex outlet, a duplex cover a few scraps of wire and a recycled power cord and a strain relief. Probably around another 5-7 bucks.

    I used two single boxes here because the original Intermatic timer needed its custom cover dial. so there was no double width cover that would work. This is much simpler and easier.

    I could use this timer for the air filter cleaner too, but I have relegated that to Google Nest Hub and a voice command now. "Hey Google, turn on the air filter for 4 hours!"

    No matter how you get it, a countdown timer is a useful function to have for a shop.
    Attached Files
    Last edited by LCHIEN; 02-16-2022, 04:24 AM.
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ -

  • #2
    My timer cost me about $800. but it also has a phone feature and email ability attached to it!

    That is a nice timer setup.

    If I didn't trust the high end Ryobi chargers so much I would probably invest in something like that. I have never had problems with overcharging the lithiums in the Ryobi 18V Intel-chragers. I have forgotten and left them in for a week or more and they work fine. Even my 10 year old 4Ah still works great and it has been left in several times. OF course, Ryobi states that it automatically cuts the charging off after it is sufficiently charged, with an occasional check and topping off if needed.

    The Ryobi 6 Bay charger only charges one battery at a time, and monitors the others, not charging unless needed.
    Hank Lee

    Experience is what you get when you don't get what you wanted!


    • #3
      I just figured out the downside of the electronic timer vs spring wound timer.
      The electronic timer uses 1.8 Watts all the time, when plugged in whether or not the load is on.
      Costs me $1.57 a year to leave it plugged in.

      Loring in Katy, TX USA
      If your only tool is a hammer, you tend to treat all problems as if they were nails.
      BT3 FAQ -


      • #4
        LCHIEN is your air cleaner shop made? My Grizzly has a factory timer at 1, 2, and 3 hour settings. I am not familiar enough with other air filter units to know if this is a common configuration or if the Grizzly has an uncommon feature.
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        • LCHIEN
          LCHIEN commented
          Editing a comment
          I have an old Delta single speed air cleaner hanging from the ceiling but it has no timer as the better models do. That's why I made my own timer. Obviously it makes a lot of sense to have a timer on the air cleaners. A lot of them with timers and multiple speeds had remote controls because climbing a ladder to start the timer is a nuisance. Does yours have a remote?
          Last edited by LCHIEN; 02-15-2022, 12:16 PM.

        • dbhost

          Editing a comment
          Yes, 3 speeds, a timer, and a remote. Although I can reach up on my tippy toes and fully control the unit manually if need be.

          Yeah if you have one of those single speed manual control models I would have done what you did. I actually ended up with a whole house squirrel cage blower that can be used for a filter, I would actually like to give it away but it may end up going to the recyclers soon. It is using up too much space and I am not going to use it.