I have been working on a 120 volt band heater vaporizer that can vaporize a hive through a 3/8" clearance hole at the back of the hive that has the hole plugged with a piece of 7/16" dowel until you need to vaporize. The first unit I made was temperature controlled with a mypin TA4-RNR and a type K thermocouple. The band heater was from Amazon, a110v-300w, 25mminternal diameter for about $8. Total cost about $50. I found pre heating for 5 minutes then inserting into the hive turning upside down putting on the cap with the 2 gram charge of OA then turning the unit the right side up vaporizing would take place in less than 1 minute. At this time a second cap could be loaded with OA to go again when the unit is moved to a new hive. So in theory after heating the device for 5 minutes a hive could be completed almost every minute thereafter. However I have found that when working in a yard with a cold breeze blowing this seems to rob some of the heat from the device and slow things down a little. I have also made a second vaporizer without the temp controller at a cost of little more than $10 and as I now know where the temp goes to I find the controller not necessary. I have used this in the yards from a battery and a $40 inverter and it works fine.
More info to follow as I progress with this project.
Johno
Johno