Adding a Power Switch to a Hot Glue Gun

About: Car Fanatic, DIY Hacker But I'm Super Lazy so dont expect much out of me

I did this modification about 8 years ago and its still running strong. 
The Hot Glue Gun (hence forth being named HGG) that i owned had two settings "Hot" (would melt hot glue) and "Warm" (wouldn't melt hot glue) but the mean issue I had with this HGG is that if it was plugged in it was on. I found that the "Warm" position was useless, and I wanted to add on/off functionality as well as a power LED. I also wanted it to be done as simply as possible. 

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Step 1: Materials and Tools Required

1.  0.33 uF 500 VAC rated cap 
2. 5mm blue LED (or different color, I used blue)
3. Hot Glue 
4. Assorted Heat Shrink 
5. Assorted Wire
6. Solder

1. Soldering Iron
2. Second Hot Glue Gun 
3. Drill
4. 5mm Drill Bit 
5. Heat Gun or Lighter 

Step 2: Circuit Bending

Picture 1 is the original circuit it shows the two different heating elements and SPDT switch.
Picture 2 is the modified circuit with an on off switch and LED

Note: The Capacitor being used must be over rated, I personally had a 1KV Mylar capacitor sitting around with the value of 0.33uF or 330nF in a AC setting this capacitor is being used more like a resistor, but for protection I also added a 10K Ohm resistor in series.

Second Note: The lifespan of the LED is being reduced significantly because its being turned off and on at 60 Hz  

Step 3: Case Modifications / Assembly

The case modifications on this project are very simple, find a safe spot and drill a 5mm hole. 
Assemble the second circuit from circuit bending step, make sure you use heat shrink.  Remember  this is AC Mains voltage, and can easily cause a fire or kill you. Now hot glue the circuit inside the case of the HGG, and reassemble the HGG. 

Step 4: It Works!!!

This is one of those Keep It Stupid Simple projects or KISS projects. 
I've had this glue one with these modifications going on for 8 years now and the LED still works so I don't think you'll run into any issues with it. 

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    6 Discussions


    4 years ago

    Looks like a good idea, I'm thinking of doing that to :)


    5 years ago on Introduction

    The LED looks bright enough! Clever way to turn it into a switch (less one heater element that probably was no good anyhow). Could you have put that LED near the tip of the glue gun for a work light? That's what I've done with several of my hand tools. The capacitor limits current to the LED so with the 10K resistor, it only uses about 6 ma. Should last a long time!

    2 replies

    You can add another one just by wiring it parallel to the other one in the reverse direction. That will also cut down on the reverse bias of both LED's to make them last longer. You may be able to lower the 10K resistance a bit too so that the work LED is brighter. The capacitive reactance is only giving about 12 ma without any resistance.

    CapacitiveReactance = 1/(2 * pi * frequency * capacitance)

    RMScurrent = voltage / (CapacitiveReactance + resistance)

    current = .9 * RMScurrent

    Frequency is 60 Hz, 50 in Europe

    Good idea... I have been wanting to make a custom outlet on my workbench for the glue gun then I can have an arduino control a relay then have time delay switch.. I always forget to unplug my glue gun!

    1 reply