I have been dabbling with DIY (thanks again, ski!), and found that Darwin can be a unique tool to dial in a mix for a specific device. There are lots of variables you can juggle, to make the juice better or worse for a particular device. Darwin lets you emulate other devices easily.
Example: I am mixing juice for a friend. I know that he has a fixed-voltage, non-regulated 3.7 volt device, and I know that he is using 2 ohm cartos. When I am broadly testing a new recipe, I mix no-nic batches of 1 or 2 ml, then check by dripping on an atty. I am not normally an atty user, but this is a good way to test a few hits, and I can easily clean and re-use. That way I'm not devoting cartos to test batches of 1 ml. As a carto guy, I don't keep many attys around. OK, I keep one. It is a fairly high resistance atty.
Solution: I do have some 2 ohm cartos, so I put one (with juice, any juice) on Darwin, and while firing, turn it down until the readout displays 3.7 volts. Since I know my friend's device is non-regulated, and will sag as the battery discharges, I'll go on down to 3.6 volts to give a more real-world scenario for him. Darwin says 5.8 watts. OK, now I just leave the wheel set there, put on my higher-resistance atty. Darwin will adjust the voltage for the new resistance to keep it at 5.8 watts. I can be more assured that *this* is what it will taste and vape like on his device.
Darwin lets me tweak juice for a specific device if I want to, without having to own multiple PVs to do so.
