After forgetting a spare set of batteries when I left the house the other day, I started thinking about building a true 5v passthrough. But, patience was non-existent by that point, so I used parts I had available from the stockroom at my employer.
Long story short: 3xAA box with an LM317HVT set at 5.5 Vout, BNC connector on the outside, a cigarette car adapter with BNC connector, and old laptop power supply (with BNC connector).
at 12 Vin, it draws 1.77 amps, which is on the high end of the regulators capabilities. (2 amps if delta V is less than 10 volts, or something close). It puts out a LOT of heat. The temp coming out of the cooling hole in the side was 60 C after less than 5 minutes of vaping, and that's including a DIY heat sink.
Fast forward a day: Wrapping things up with this project, to solve the thermal issues, I mounted a 40mm fan on the side, added a TO-220 heat sink to the regulator, and wrapped up some loose ends.
After mounting the fan, the unit draws a little over 2 amps. The fan operates when the on switch is turned on, the atomizer only fires when the momentary switch is depressed.
Extremely inefficient and unnecessary? Of course! But DIY isn't always about making something better, sometimes it's just about doing what you can with what you have available.
Edit: Pictures added
Did some testing last night with a K type thermocouple placed between the heat sink fins. When airflow was blocked, temp reached 45 C. With airflow, only reached 35 C. Temps were recorded after 5 minutes of near-constant vaping. With normal, leisurely vaping, temps hovered around 30 C.
I'd take a few pics of the internals, but I do not have any more zip ties at the moment. Once I decide I'm done messing with it, i'll probably just epoxy the box shut.
Long story short: 3xAA box with an LM317HVT set at 5.5 Vout, BNC connector on the outside, a cigarette car adapter with BNC connector, and old laptop power supply (with BNC connector).
at 12 Vin, it draws 1.77 amps, which is on the high end of the regulators capabilities. (2 amps if delta V is less than 10 volts, or something close). It puts out a LOT of heat. The temp coming out of the cooling hole in the side was 60 C after less than 5 minutes of vaping, and that's including a DIY heat sink.
Fast forward a day: Wrapping things up with this project, to solve the thermal issues, I mounted a 40mm fan on the side, added a TO-220 heat sink to the regulator, and wrapped up some loose ends.
After mounting the fan, the unit draws a little over 2 amps. The fan operates when the on switch is turned on, the atomizer only fires when the momentary switch is depressed.
Extremely inefficient and unnecessary? Of course! But DIY isn't always about making something better, sometimes it's just about doing what you can with what you have available.
Edit: Pictures added
Did some testing last night with a K type thermocouple placed between the heat sink fins. When airflow was blocked, temp reached 45 C. With airflow, only reached 35 C. Temps were recorded after 5 minutes of near-constant vaping. With normal, leisurely vaping, temps hovered around 30 C.
I'd take a few pics of the internals, but I do not have any more zip ties at the moment. Once I decide I'm done messing with it, i'll probably just epoxy the box shut.
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