I've never understood all the problems users and even manufacturers have with making log-style (~12 volt, hand-held, convection) vaporizers temperature adjustable. Perhaps, there is a middle ground that everyone, even manufacturers, can accept. What I propose is useful for those wanting slightly higher temperatures; any lower temperatures; or just wanting the option of being able to set their temperature wherever they want (within the acceptable operating range of their unit).
Why not use a slightly higher voltage power source, but still less than car voltage (<14 volts; which seems to be acceptable with most or even all of the log vaporizers), say 13 or 13.5 volts, combined with a low-voltage (12-14 volts, e.g., car/truck/RV/boat) solid-state dimmer switch, costing as little as $10, which allows you to adjust the power downwards. You can use such dimmers with 1) your current 12 volt power supply if you want to run cooler than normal (surely, acceptable to all manufacturers) or 2) with a slightly higher, e.g., 13-14 volt, power supply which you can modulate down with the dimmer switch to your own desired hotter than 12 volt-supply temperature. If nothing else, a dimmer should be useful for those having a problem with their vaporizer running too hot in their car/RV/boat -- just use this to adjust down the power.
For example, see the "12 Volt Universal LED Dimmers" at
http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=/hobby.htm see the "12 Volt Universal LED Dimmers." Check out the model for $9.95 at
http://www.superbrightleds.com/pdfs/LDP-2A.pdf. You just plug this in between your power supply and vaporizer (presuming that both have the fairly standard 2.5 mm/type M connectors). I have been using the LDP-2A, costing only $9.95, continuously (24 x 7) for well over a year with a DIY log-style vaporizer. It works with excellent reproducibility (measured with a digital thermometer and multimeter).
For ~$15 with postage and presuming you use a ?12 volt power supply that without any down-modulation is ACCEPTABLE BY THE MANUFACTURER for your model vaporizer, this option appears to deserve further consideration and testing by FC members. Perhaps, manufacturers can comment about this for their units. If nothing else, those manufacturers themselves selling >12 volt, e.g., 13.5 volt, adapters might consider bundling-in dimmer switches.
For those familiar with electricity: These dimmers linearly limit from 0%-100% the current (amps) flowing while the voltage remains constant, e.g,. if a vaporizer supplied 13 volts naturally draws .55 amp, with a multimeter you can watch the dimmer linearly vary amps from 0-.55 while voltage remains constant. This is unlike most variable power supplies, which vary voltage while current/amps remains constant. Note, the specs for these dimmers state 12 volts DC, but I spoke with a knowledgeable person with the company who stated that of course what really matters is the power [remember Ohm's Law; power (watts) = volts x amps] in the circuit, and of course these dimmers are made to be used with ~14 volt car/truck/RV/boat electrical systems. Even running with a 14 volt power supply, none of the log-style vaporizers draw enough current (amps) to be a concern for stressing these dimmer switches (with the <$10 model having a 24 watt capacity, e.g., upper limits of 12V x 2A or 14V x 1.7A).
