If you’ve researched building your own variable voltage e-cigarette, chances are you’ve heard of the “evercool” setup. This pictorial will, hopefully, paint a clear picture of the exact connections that need to be made in a format that’s easy to understand for non-electronic technicians. But first, here’s some info on this efficient and powerful module that makes all the magic happen.
The PTR08100 and PTR08060 from Texas Instruments are switching step-down regulator modules. The only real difference between the two is the 08100 can handle up to 10 amp output and the 08060 can handle up to 6 amps (and the ptr08100’s inductor is a few mm larger than the 060). Both can handle way more than enough power than you’ll ever need for our purposes. Typically, even with dual coil setups, the most power that will ever actually be used vaping is around 1-2.5 amps. These types of modules are, in my opinion, the most efficient and reliable method to achieve an adjustable range of voltages in a device.
They both feature an on/off inhibit feature which means you can have your button be a little tactile “clicky” pushbutton, but the way it works you will need a normally closed switch in order to implement (as shown in the picture below).
They also feature both overcurrent and overtemperature protection on the output side. This basically means that if your atomizer shorts out or the positive pin of your connector hits the negative side it will shut down the output (put out significantly less current) until the short is removed. This is a great protective feature but does not protect anything battery-side from shorts so it’s always better for your safety to use protected batteries, as lithium ion batteries CAN explode!
As stated in the datasheet, you will need at least a 4.5v power source, with the maximum of 14. This means that you will either need to use two lithium ion batteries in series (or stacked, 8.4v at full charge) or some other kind of DC power source capable of outputting at least 3 amps. I used a 12 volt LED driver (capable of 6 amps) to make my own VV pass-through – which worked quite well.
For switching the load (the fire button) it is best to use a switch rated for at least 3 amps. Alternately, you can make it so the batteries always power the circuit but use the on/off inhibit with some form of “normally closed” switch. These kinds of switches let power through until pressed, when it stops the power from passing through. So basically the chip will always be disabled until you press the button and it outputs power to your atomizer.
All other components needed and details are in my draw-up below.