Dynavap Induction Heater Box With PWM

A simple box for a DIY Dynavap induction heater. Designed to accommodate a PWM module for adjustable duty cycle (must be used with a MOSFET). 

Recommend printing in PETG for better tolerance of heat, but I used PLA and haven't had any issues after nearly a year of use. Just don't play around by heating random metal objects until they're red hot and you'll be fine (ask me how I know lol).

The holes are 3.4mm in diameter. Should work with M3 or M4 screws. Recommend button head screws as they won't sink into the plastic. If you don't have button head screws, then use appropriately sized washers. 

FreeCAD files included if you wish to modify the design. I published this in the public domain, so you don't need to credit me as the author (though credit is always appreciated :)

The wiring is as follows:

Momentary Pushbutton

• C (Common) to MOSFET signal TRIG input
• NO (Normally Open) to PWM+ output on PWM module
• NC (Normally Closed) to GND
• + to +12 V (if using a power toggle switch then connect this to the switched terminal instead of connecting directly to power supply + wire)
• - to GND (recommend using always-connected ground, i.e. don't wire the ground to the toggle switch if using one)

PWM Driver

• +/Vcc to +12 V 
• - to GND 
• PWM + to NO (Normally Open) on momentary pushbutton
• PWM - to MOSFET signal GND input

MOSFET Driver

• V+ in to +12 V
• V- in to GND
• V+ out to induction driver + input
• V- out to induction driver - input

Parts used are shown in the photos. I didn't include links as they will probably change, but these parts are very common and sold by different vendors under different names.

I included a coil chuck tool that can be used to more easily wrap the coil. I suggest using 16 AWG enamel coated wire instead of the included coil as you can wrap it to the same diameter of the glass bottle. Make sure to match the number of turns as the included coil (in my case it was 10 turns). 

I used a generous amount of JB Weld to secure the coil to the glass. Leave a few mm of space between the bottom of the coil and the bottom of the glass. You want the tip of the dynavap cap to be just below the last turn of the coil, otherwise it will click too early. If you leave too much space then it will likely combust before clicking (and will cause the dynavap body to get warmer as well). It's better to leave too much space than too little, as with too much space you can simply hold the vape a bit higher as you're heating it. Too little space and you won't be able to adjust your technique to heat the right spot.

For the rubber gasket under the lip of the bottle, I used one from a rubber gasket/o-ring kit from Harbor Freight. Hot glue will also work. Unless you're in a large group taking turns using the box, it's unlikely to get hot enough to melt the glue or deform the box.