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Hot Glue Gun Power Indicator

Discussion in 'General Electronics Discussion' started by whiterabbit, Dec 3, 2013.

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  1. whiterabbit


    Sep 14, 2013
    This project is fairly straight forward, and mostly based on this instructable:

    This seems to work, but is that the best solution for a power indicator circuit?

    My goal is to follow that instructable with only minor changes... I want to add a power toggle switch. The switch I have that fits with my glue gun is metal. It's rated at 250v so it should work. However, because I'm working with mains power I want to cover my bases here...

    Should I replace the existing hot/neutral power cord with a hot/neutral/ground cord? If so... how should I attach ground to the chassis? Pretty much everything is plastic except the power toggle and the heating element itself (screws, too). But most of the metal is totally isolated, sans toggle.

    Thanks in advance for any input!!
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    That's a reasonable way to make a simple, cheap, reliable, non-heating power indicator. The series capacitor (0.15 µF for 230VAC or 0.33 µF for 110VAC) should be an "X1" or "X2" safety rated part like these:
    0.15 µF, 440VAC (to suit 230VAC mains supply):
    0.33 µF, 275VAC (to suit 115VAC mains supply):

    I would use a switch with no accessible metal parts. Even if you have to buy one. I think this is a better option than earthing parts of the glue gun. As you say, the glue gun should also be completely plastic except for the piece where the hot glue comes out, which is supposed to be double insulated (look for the square-inside-a-square symbol on the case somewhere).
  3. whiterabbit


    Sep 14, 2013
    Thank you for your help!

    I will nix the earthing and focus on finding an insulated switch. I do have one with no external metal, but its rather large and I don't know if it would fit the form factor of the glue gun. Anyways, I can figure that part out with a little searching I'm sure. I'll get the cap ordered quickly so I can get this tool back up and running :p

    I looked on both halves of the case and also on the heating element but didn't see any symbols other than the one indicating a recyclable material. Maybe it was on the original packaging...? Or maybe it isn't double insulated haha
  4. whiterabbit


    Sep 14, 2013
    The parts shop was closed this weekend so I couldn't get the right kind of cap. I ended up getting a cheap night light from the grocery store; stripped it down, reorganized the circuit on perf board to fit the handle, and added an insulated switch.

    Turned out pretty well!

    Attached Files:

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