LM2596 questions.....

[seniorphil]

Hi,
I want to build a mains operated mod. I have a LM2596 with LED display. I was thinking of de-soldering and removing the +/- input and output connections and soldering my wires straight to the board. Mainly because they are massive and this will slim the board down and make it surface mountable.
I currently(no pun intended) have a choice of 20 transformers. I've checked the data sheet and it will handle upto 40v and it says it has a 3 amp limit. How many amps do I need to vape? I had my eye on a transformer thats output was 15v 2.5amp, is this suitable? I was just getting my head around the volt/watt relationship, now amps are playing with my brain.
Also I am thinking of replacing the potentimeter, so I can locate it on the side of the device. What size pot would I need?
I am sorry if these questions have already been asked, I couldn't find them.

Cheers,

Phil.

[giles]

How many volts are you putting through it? 40v at 3 amps sounds like 120 watts to me, 15v at 2.5 would be 37.5 watts. Electronic mods usually have a power limit of about 15 watts. 1 amp sounds better.

I don't want to sound alarmist or, god help me, condescending, but I can't help wondering whether if you have to ask then you shouldn't be doing it. People usually don't put anything in their mouth while it is connected to the mains. Please be careful.

[blakey]

That all depends on how you vape, a .7ohm coil from a freshly charged battery giving out 4.2v will draw around 6amps or around 25w
A standard 2ohm coil at 8w or 4v will draw around 2amps
You need to know what your preferred ohms vs volts or power is before you can decide whether or not 2.5amps will suffice

[Deleted]

Hi Phil ... The current that you will draw depends on the wattage you like to vape at and your atty resistance.

For example if you vape at 10 watts with a 1.8 ohm atty then using the formula V = square root of (W x R) your voltage will be 4.24 volts, and using the formula A = W/V your current will be 2.36 amps.

However if you wish to vape at the same 10 watts with a subohm coil, say 0.8 ohms, then your voltage will be 2.83 and your current will be 3.54 amps

Sorry, but can't answer your potentiometer question ... good luck with your build

[seniorphil]

Dec 18, 2013 13:48:25 GMT @freefromsmoking said:

Hi Phil ... The current that you will draw depends on the wattage you like to vape at and your atty resistance.

For example if you vape at 10 watts with a 1.8 ohm atty then using the formula V = square root of (W x R) your voltage will be 4.24 volts, and using the formula A = W/V your current will be 2.36 amps.

However if you wish to vape at the same 10 watts with a subohm coil, say 0.8 ohms, then your voltage will be 2.83 and your current will be 3.54 amps

Sorry, but can't answer your potentiometer question ... good luck with your build

Cheers,
I make my own coils at 2 ohms and vape at 8.5-9 watts. So my voltage is 4.24 v giving me 2.12 amps.
So as long as the supply is capable of delivering over 2.12 amps I should be good to go. Will anything under that not produce my normal vape?

Cheers.

[maccafan]

Get an old computer power supply and wire it up to the 5 volt line and put it under your desk

It'll rip your throat out if you so wish and you can pick one up for under a £1 if you don't have one lying around .

[Deleted]

Dec 18, 2013 15:40:36 GMT seniorphil said:

Dec 18, 2013 13:48:25 GMT @freefromsmoking said:

Hi Phil ... The current that you will draw depends on the wattage you like to vape at and your atty resistance.

For example if you vape at 10 watts with a 1.8 ohm atty then using the formula V = square root of (W x R) your voltage will be 4.24 volts, and using the formula A = W/V your current will be 2.36 amps.

However if you wish to vape at the same 10 watts with a subohm coil, say 0.8 ohms, then your voltage will be 2.83 and your current will be 3.54 amps

Sorry, but can't answer your potentiometer question ... good luck with your build

Cheers,
I make my own coils at 2 ohms and vape at 8.5-9 watts. So my voltage is 4.24 v giving me 2.12 amps.
So as long as the supply is capable of delivering over 2.12 amps I should be good to go. Will anything under that not produce my normal vape?

Cheers.

Hi Phil  ... to draw less than the 2.12 amps you would need to increase the resistance of your coil or decrease your watts