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I'm trying to control the current going into my hot glue gun which in turn allows me to control the temperature of it.

Saw some online diy projects doing it with a dimmer switch, but I'd like to have the knob on my hot glue gun, and the dimmer switch wouldn't possibly fit into it.

I'm guessing a variable resistor could do the work, but are there any variable resistors out there that wouldn't blow on 240V?

EDIT : So the variable current with a dial part now couldn't do, I'm thinking to add a slide switch (or some other type of switches that might work better in this scenario) which I'll then be able to choose a multiple of fixed current. Other that the diode method Steve G suggested, are there anyway I can reduce to a fixed current? Could resistors work at such a high power? My hot glue gun is rated at 60W.

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  • \$\begingroup\$ No, which is why dimmers are used. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Jan 27, 2016 at 9:04
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    \$\begingroup\$ Yes, indiamart.com/viduit-electricals/power-rheostat.html but they wouldn't fit in either! \$\endgroup\$
    – Icy
    Commented Jan 27, 2016 at 9:06
  • \$\begingroup\$ I have seen two-knob dimmer like this: ecx.images-amazon.com/images/I/21W2cKfG56L._SX300_.jpg that have two small sealed dimmer modules inside. They are expensive though ! Also check that they work with the small load of the heat gun, some dimmers need a load above 40 W or so. \$\endgroup\$
    – Bimpelrekkie
    Commented Jan 27, 2016 at 9:12
  • \$\begingroup\$ I doubt whether you'd ever be able to build anything that works into the gun, so my suggestion is to bite the bullet, go to Ebay, and search "VARIAC." \$\endgroup\$
    – EM Fields
    Commented Jan 27, 2016 at 9:36
  • \$\begingroup\$ A diode in series with the supply will give you half power. \$\endgroup\$
    – Steve G
    Commented Jan 27, 2016 at 10:41

2 Answers 2

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A series resistor is a bad idea since it will dissipate significant power. The heater in the glue gun will run cooler as you intended, but the resistor dropping the voltage will get hot. The total will still be cooler than just the heater before, but this is not only wasteful of power, it will make the glue gun too hot to hold.

Dimmers work by by turning the power on and off rapidly. They achieve different dimming levels by modulating the average ratio of on to off. These things are more efficient since a ideal switch doesn't dissipate any power. There is no current thru it when off, and not voltage across it when on.

Put the dimmer somewhere in the cord between the plug and the glue gun. Personally I wouldn't want a glue gun with a klunky dimmer duct taped to it. The response of the heater in the glue gun is on the order of a minute or more, so you wouldn't be adjusting the dimmer every few seconds anyway.

Another option is a variac, but at several times the cost of a glue gun, that's silly unless you have one lying around.

The obvious best option is to buy a better glue gun that has temperature control, or at least power control, built in. You are making this way too complicated.

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A phase-control dimmer (ideally controlled by temperature feedback) is the "right" answer, but you could use a series resistor... commonly known as a lightbulb. Horribly kludgey though and probably not particularly safe.

For example if you put a 60W lightbulb in series with the 60W heat gun, it will run at quarter-power (actually a bit more because the lightbulb will not heat up properly and will therefore have lower resistance than it was designed to).

Considering that you can buy a high-quality temperature-controlled glue gun for $40, I don't see the point of this hackery though.

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