Dna 40 question am i going to have problems with temp sense

[newt2351]

Hia all,


Well just in the middle of building my dna 40 Mod based on CHana, FT box, with nice buttons and Fatdady 510 connector , and I got to thinking mmh may have a problem.
Well, i want to light the diode in the switch, all good but connecting it to the output of said dna 40 board may cause me problems with temp sense circuit


My thinking is this :- Temp sense probably works on the basis that when you pass a current through a known material in this case zinc alloy 200 for a temp increase from room temp to 400 degress the zinc will produce a resistance of" x" amount, and a bit more current and its more resistance and its X+Y resistance and 600 degrees.


So, if im adding resistor to output of DNA40 to power diode, am I going to mess up the temp sense thing?

any solutions thoughts etc?

 

[rhelton]

Any idea what current runs thru the fire button, could you possibly run off of that.

 

[WKS01]

I have not looked heavily into the operation of the DNA40 heavily, but my assumption would be the small current the LED is using would not drastically change the temperature sensing circuit. The LED would be using maybe 20mA.

 

[newt2351]

I HAVE AN ANSWER following some experimentation and calculation
Hia all, spent yesterday looking at my friends vaperflask dna 40 and played about with it in temp mode to see how it does things.
Yup, the nickel rapidly changes resistance with heat generated by the current passing through it, as suspected.

so, what about the resistor on the output protecting my led in the switch? well did some math around the effect of two diffrent types of circuit:-

simple 1:- resistor and led



so not really a problem as the difrence in resistance is tiny 1.49522 ohm instead of 1.5 ohm.
However,
The DNA 40's pre-heat coil function has the wattage on fire up leaping up all over the place, so in the interests of keeping things working as they should i would recomend the solution provided by VAPANT on this forum using his desgin to go forward.

http://www.e-cigarette-forum.com/forum/modding-forum/555131-wiring-led-button-switch-vw-mod.html

This solves the wattage problem and Uses 10K ohm resistor giving a new resistance of 1.49977.ohms so a total solution
picture from vapant's post many many thanks to him

 

[newt2351]

Hi all i thought i would open the question to evolv themselves and thanks to there excellent customer support they have provided the following information :-

Connect the LED between the negative side of the fire switch and ground or B-

Many thanks to brandon at evolv