I'm building a variable voltage box mod and had a question about setting the voltage. I found this chart of shows a good guideline for carto Ohms / Batt Voltage / Watts http://img689.imageshack.us/img689/2006/unled66.jpg but when I adjust my variable voltage, do I set the voltage with the cartomizer removed or with it attached? Because I know the voltage going through the cartomizer is less than the actual battery (or adjusted) voltage due to the carto resistance. So going by that chart, if I had a 3.0 Ohm cartomizer and wanted to run it at 8.33 watts, I would need to set the voltage at 5.0 volts with the carto attached (which would actually be higher than 5.0 volts with the carto removed), correct?
VV mod, set voltage with or without carto attached?
- Thread starter bluegizmo83
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in short, yes. if you want to be more accurate, you should always check the voltage underload (with carto attached) to see what the output is with any particular atty/carto. keep in mind, as you use the carto/atty it slowly increases in resistance from use. thats why a variable wattage board can be more of a set it and forget it mod, and a vv device you fiddle with the pot dial a little more.
not sure this helps or not.
not sure this helps or not.
Thanks that definitely helps! I've never heard of a variable wattage board, I'll have to look into that. I've never had a variable voltage mod either, but I've heard great things about this PTR08100W Adjustable Switching Regulator and thought I'd give it a try since you can get a free sample chip (with free shipping too) directly from TI (Texas Instruments). My plan is to build it in an Altoids box using two 14500 batteries at first (since I already have those) and then upgrade to two 18650 3100mAh batteries.
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voltage drop under load varies by the regulator. Linear regulators will give a pretty good drop under load even some of the cheaper older switching regs will drop a bit. The PTR08100w is a finely tuned switching module. The tests i have done with it under load it drops less then 3 thousands of a volt while under load. So if you set it to 5.003 volts un loaded , under load you would have 5.000 volts. The difference is so small you would never notice it while vaping. You will also be hard pressed to find a multi meter that can read thousands of a volt. The PTR080100W can give you a stable wattage in the hundredths of a watt. The variable wattage boards give you 7.1 , 7.2 , 7.3 and so on if you did the math with a PTR hooked to a precision potentiometer you can get 7.10 , 7.13 7.16 .7.2 watts and so on. Of course i doubt anyone would be able to notice the difference while vaping. I guess my point is the PTR might be a variable voltage reg but if you look at the math it produces a extremely stable wattage threw the entire cycle of the batteries.
Good to know! Thanks I appreciate the info. I just received my PTR080100W today and realized it does not have standard (0.1") breadboard style pin spacing... So I'm going to have to work out some sort of connector to plug into the regulator and the solder the connector leads to my pcb. I think I read somewhere that a PC CD-Rom drive audio cable will work as a connector for this regulator. Any thoughts on what would be the best method of connecting this thing to a 0.1" spaced pcb?
Sorry, but this didn't fit. I believe Bubo disproved it in BigBlue's thread. I ended up using a PCB and IC connector in between and bent the IC pins to avoid bending the 8100's pins. The drawback was this made it rather big.
Any idea where I could find one of those? The 8100's pin spacing is 0.067" or 1.70mm, so I need either a cable with a 5-pin female end with that spacing, or a IC Connector, or something. Ive tried searching around and can not find anything with that pin spacing ...
EDIT: Nevermind, I made it work. I just broke off pin 1 (inhibit pin) since i won't be using it anyway and then bent the other four pins enough to fit in my 0.1" spaced PCB.
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