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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: DNA20 / Mech
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Author Topic: DNA20 / Mech  (Read 7575 times)

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Offline studiovape

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DNA20 / Mech
« on: December 20, 2013, 07:49:02 PM »
Hi Breakthru and other bright minded folks,
I have a question. 
I am building a brass/copper DNA20 bottom feeder box and I want to incorporate a switching mechanism/method to convert the mod from DNA20 vw to unregulated mechanical. 
Some of the more specific questions are how does the  negative wiring for the battery connections and atty connections respond to being connected via the metal chassis?
And. 
What is the most efficient and compact method of isolating the DNA20 chip via switches/switch and or diodes, when flipping to mech mode?
Thanks heaps in advance. 
SV

Offline CraigHB

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Re: DNA20 / Mech
« Reply #1 on: December 21, 2013, 10:24:50 AM »
Diodes tend to waste a lot of power, especially for high currents.  Power MOSFETs can do the same job actively without wasting much power at all.  You could probably just leave the ground common and connected full time.  Use a low current switch to activate a MOSFET connected directly from the battery to the atomizer connector or another connected to the DNA20.  I'd have to think about it to say for sure, but you'd probably need one on both input and output for the DNA20 and then another one to switch power directly to the atomizer connector.


Online Breaktru

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Re: DNA20 / Mech
« Reply #2 on: December 21, 2013, 11:01:33 AM »
I agree with Craig about using Mosfets. They could handle the amperage using it as a Mech w/ sub ohm and hi amp batts.

I came up w/ a drawing using no mosfets and a 3PDT switch. Unfortunately the 3PDT and the fire PB would have to handle the current for a sub ohm making the switches rather large. Not practical. Better off w/ Craigs idea with the mosfets.

Offline studiovape

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Re: DNA20 / Mech
« Reply #3 on: December 21, 2013, 11:29:12 AM »
Thanks for the replies  Craig and Breakthru, it has given me some food for thought. I have a couple of mosfets I bought a while back to make some touch switches from Raidys specs, but. never got round to using them. I had thought about using a PDT style switch and a HD pb for the fire button, but 22mm was the smallest diameter pb I could find with decent amp capability for the mech functionality.
I was concerned about the power feeding back to the DNA module via the atty connection ( probably only on the positive polarity?) during mech mode, (and would have been keen to see your wiring diagram for the the 3PDT switch Breakthru, and your advice on the most compact switch capable of decent amp handling).
I'm showing my ignorance here, but I'm not sure how to wire up the multiple mosfets to achieve the mode switching and what lower amp compact switches would need to be used, and how all that would affect the delay in start up of the DNA20 in VW mode. It's late/early here I the back waters of Queensland Australia, so my mind is fried and tired. That's my best excuse. I feel a little out of my depth. But I will not give up:)
« Last Edit: December 21, 2013, 11:34:27 AM by studiovape »

Offline CraigHB

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Re: DNA20 / Mech
« Reply #4 on: December 21, 2013, 11:43:44 AM »
You run into the same trouble with size when working with the through-hole MOSFETs.  To make things small enough to fit well in an e-cig mod, you need to use the surface mount jobs so some PCB making and soldering of SMD components would be involved.  Not a big deal really.  Once you've done it and gained some experience it's really a non-issue. 

Vishay has recently expanded their selection of Powerpak 12-12 parts which are quite small and able to efficiently handle currents as high as 20 Amps.  I like Vishay MOSFETs a lot and they've been my go-to source lately;

http://www.vishay.com/mosfets/powerpak-1212-8-package/

MOSFETs are super easy to wire, just like a switch with an extra line for control.  You do have to be careful with them since the gate terminal is delicate and can be damaged by ESD very easily.  Once they're installed with a resistor conecting the gate to the source, there's not as much concern there.  Though if it's all too much and size is not that much of an issue, it would be a lot easier to just use a big double pole double throw switch.

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Re: DNA20 / Mech
« Reply #5 on: December 21, 2013, 12:37:39 PM »
Some one may want to check this over. I think it's okay. Just that the 3PDT will be large.
The low current tact PB is really a N/O for both poles not like shown.
« Last Edit: December 21, 2013, 12:42:44 PM by Breaktru »

Offline studiovape

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Re: DNA20 / Mech
« Reply #6 on: December 21, 2013, 08:47:19 PM »
Thanks so much  Breakthru. I am assuming the DNA20 is connected from its battery in + and - terminals to the battery full time, and would just go into sleep mode when the mod is in its mech position setting?

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Re: DNA20 / Mech
« Reply #7 on: December 21, 2013, 08:57:57 PM »
Thanks so much  Breakthru. I am assuming the DNA20 is connected from its battery in + and - terminals to the battery full time, and would just go into sleep mode when the mod is in its mech position setting?

You are welcome and Yes sleep mode after the sleep time out. Yes to (+) and (-)

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Re: DNA20 / Mech
« Reply #8 on: December 22, 2013, 05:00:56 AM »
Wow size really is becoming an issue LOL, after some research on available 3p2t switches. I'm assuming I need at least 6A @125v AC rated switch to handle the 4.2v DC my 18650s will put out on a full charge, although the current while the switch is being thrown should be very low as I won't be firing the device at this moment.
this is 5A @ 125v AC, is this up yo the job I wonder? http://www.ebay.com/itm/5-Pcs-Mini-3PDT-ON-ON-5A-Red-Toggle-Switchs-9-Terminal-/271158268025?pt=LH_DefaultDomain_0&hash=item3f224ad079

Any advice on where to get a more compact switch to do the job would be much apreciated.
Looking at the diagram kindly supplied, I'm wondering if a 2p2t switch could be used if the negative on the fire terminal is already grounded, this would save some bulk on the switch maybe.
My appologies if this is all driving this thread off topic, maybe I should have started a new thread?
As much as I love my DNA20 modules, I am not always happy to rely on complex electronics when I come to stepping out of the house with just one mod,
so I though It would be cool to incorperate this DNA20/Mech switching option into my latest bottomfeed mod.
I am prepaired to assign some additional realestate to accomplish this, but it is all looking a little bleak at present despite the much appreciated advice I have received.
« Last Edit: December 22, 2013, 05:05:57 AM by studiovape »

Offline CraigHB

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Re: DNA20 / Mech
« Reply #9 on: December 22, 2013, 03:09:26 PM »
I think you can probably count on your DNA20 to be devoid of any failures that could leave you without an e-cig.  I don't know that for a fact, but I've not heard of any reliability issues with it.

The only real advantage I can think of is for situations where you'd like to use the mod for an ultra-low resistance atomizer.  At one point I actually considered incorporating an unregulated mode for my own mods to allow this, though it presents problems with measuring current that I didn't feel were worth the trouble to resolve.  It's moot now anyway since the VV design I'm currently working on will be able to handle atomizer resistance as low as .2 Ohms.

As much trouble as it is to incorporate the circuitry, I don't know if it's something I would actually put the effort into.  I mean, you could just bring a mech with you as a backup for the DNA20 in the unlikely event it suffers a failure.

If it's something you're intent on doing, you should be able to do it with a double pole, double throw switch.  Just switch power and put a 10k resistor inline with the triggger connection for the DNA20 so it can't draw power through the trigger when powered down.  Also, since voltages are lower, a switch rated for something like 3A and 125V or 5A and 24V should be able to handle the load no problem.

Offline studiovape

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Re: DNA20 / Mech
« Reply #10 on: December 23, 2013, 03:44:30 AM »
Thanks for the feedback Craig,
the reason I am keen on the Idea is for severalfold, firstly all my mods I am building at the moment a bottom feeders, so juice  ingress into the board/switches & connections etc is always a risk however careful one might be water proofing and sealing up critical areas.
Secondly this is going to be a purposefully bulky device, with a few 'additions' not normally seen on a bf mod,(I can't say any more right now without ruining the surprise LOL).
Thirdly I have, very occationally been known to be clumsy around water, and just want cover my vape ass.
None of this is a reflection on the reliability of the the Evolv board.
I have In the past made mods to be as ultra compact as possible, and probably will do again, but this is not my sole aim with this one.
The design phase of this mod is a slow and thoughtful one, as I gather knowledge & parts, and experiment different with different ideas.
It may end up incoperating many, or very few of the concepts I am currently throwing around, this build for me is as much about the journey as the destination.
Thanks again for all the helpful hints and advice , all of which I have taken on board.
SV


Offline CraigHB

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Re: DNA20 / Mech
« Reply #11 on: December 23, 2013, 05:53:09 AM »
Oh yeah, e-liquid is poison for electronics.  It's more conductive than water and it's pretty corrosive to soft metals.  I actually seal my enclosures thouroughly aside from a safety vent on the bottom.  It seems to do the trick.  I've not had any juice leakage inside the enclosure.  My early mods suffered from juice exposure and they would fail on occasion from getting juice on the PCB, but it wasn't a problem to clean it with some pure rubbing alcohol.  They always came back to life after cleaning the juice off.  Though, I did kill one mod when I allowed juice to remain on the PCB too long.  It ate through some of the circuit traces.

So yeah, a wet box that does not have very good protection against leakage for the electronics can give you trouble.  If the circuit board is exposed to juice for an extended period, it will destroy it.

I have yet to drop one of my mods in standing water, but since the enclosure is not waterproof, it would probably kill the mod.  So yeah, that's always a concern.  It hasn't happened yet, but will probably will happen one of these days.  That's the downside of an advanced mod, it's not indestructible like a quality mech.  But, they have their advantages so it's just the cost of the features they offer.

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