DIY Hot Glue Gun Upgrade for Better Performance

If you're interested in DIY modding your Fuge hot glue gun, check out this article. In the previous DIY: Upgrade Your Lithium Hot Glue Gun, we used a PTC at 230°C. If you feel like this setup isn't very practical—slow heating, taking around 5 minutes to warm up, high power consumption, and a short runtime of only 20 minutes—then it's time for a new modification. This time, you can upgrade to a larger battery.

The Fuge gun uses a 4V battery, while the larger battery is 20V. We will use the LM321 low-voltage version of the operational amplifier, with the reference voltage set to 2.495V using the 431.

For this modification, you'll need a nickel-chromium alloy heating element and temperature control.

The LM321, along with MOSFET control, can be paired with an MF58 glass tube thermistor. The surface-mount MOSFET may not withstand a 2A current, so two MOSFETs can be connected in parallel to output.

Here's a close-up of the circuit board.

The potentiometer part.

If you think the tip is too thick for precise work, you can attach a copper tip or use a ballpoint pen's nib.

The working state is shown in the image below.

The side heating light turns off when the temperature is reached.

The charging state is shown in the image below.

The power is still 8W, but the heating time is reduced to 2 minutes. Since the temperature control uses intermittent heating, it should be more energy-efficient than before.

After testing, the preheating takes 2 minutes and 40 seconds, with a standby time of 1 hour. Paired with a power bank, this setup becomes quite practical.

Finished!