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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: Tact switch and mosfet transistor questions
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Author Topic: Tact switch and mosfet transistor questions  (Read 131976 times)

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Offline longwhiteclouds

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Re: Tact switch and mosfet transistor questions
« Reply #100 on: September 02, 2014, 09:54:03 PM »
Spent too much on shipping in the last few days. I will try that one next time. Thanks for all the help.

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #101 on: September 02, 2014, 10:33:41 PM »
If you're going to use a high side NMOS driver, you can use any MOSFET really.  The driver will provide a 5.4V gate-source voltage so you don't need a low threshold voltage.  Go for the lowest on resistance.  This one is better;  http://www.nxp.com/documents/data_sheet/PSMN1R1-30PL.pdf 

The best P-channel I've come across for use as a user power switch is this one; http://www.vishay.com/docs/62860/si7157dp.pdf
Thank you. Its the smd route. Hard to believe something this small can power a mechanical mod.

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #102 on: September 03, 2014, 03:30:36 PM »
It comes down to how much heat the part produces.  At 20A with 2 mOhms on-state resistance for that PMOS I mentioned, the transistor has to dissipate 800mW which isn't all that much for a part that size.  Consider those little through hole resistors can handle 250mW.  Also, you're not powering an atomizer continuously so there's less heating anyway.

The ratings you see in the data sheet are for a part mounted on a 1 inch square pad of 2 oz. copper where a lot of heat can be transferred through that big drain pad. 

The mechanical switches with high ratings probably have more resistance than that transistor does.  They make more heat, but they're also a lot more massive so they can handle more heat before they get noticeably warm.

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #103 on: September 05, 2014, 12:03:13 PM »



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Re: Tact switch and mosfet transistor questions
« Reply #104 on: September 05, 2014, 04:04:05 PM »
Nice work David. Very neat and orderly  :rockin smiley:

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #105 on: September 05, 2014, 04:12:28 PM »
^ This mofo showing off with that purdy wire dip and neatly routed

awesome david

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Re: Tact switch and mosfet transistor questions
« Reply #106 on: September 05, 2014, 05:16:44 PM »
David: have you thought about putting the polarity labels on the batteries as well. I usually have to check the batts polarity more than once before inserting into the sled. Especially with flat top batts.

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #107 on: September 05, 2014, 07:51:45 PM »
Good idea, i'll see what I can come up with

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #108 on: September 07, 2014, 06:10:44 AM »
Good idea, i'll see what I can come up with

David, where did those battery decals come from?

Offline david4500

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Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #110 on: September 09, 2014, 04:06:36 PM »
Got all these parts and Im I didn't make a mistake. How are 4-3amp hold fuses going to work in a parallel 18650 un-regulated box. Mabye Im thinking of this wrong but as soon as It gets hit with a sub ohm load wont they be exceeded?

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #111 on: September 09, 2014, 06:44:53 PM »
Four fuses with 3A hold in parallel will provide a 12A hold and typically a 24A trip.  Usually the trip current is double the hold current, but not always, depends on the fuse.  You can draw up to 24A without the fuses tripping, though they may trip a little lower if there's any pre-heating and there's some derating there.  For sure you should be able to pull 20A without issue.  That will get you down to about 200m Ohms.  That's quite low, but if you are compelled to run an atomizer lower than that, you'll need fuses with a higher rating.

Offline dc99

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Re: Tact switch and mosfet transistor questions
« Reply #112 on: September 09, 2014, 07:04:10 PM »
Thank you Craig. Guess Im over thinking things. Thank you guys for bearing with a novice.

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #113 on: September 09, 2014, 07:13:37 PM »
Welcome, enjoy your mod :)

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #114 on: September 09, 2014, 08:19:45 PM »
Input voltage (4.2-3.0) doubled and outputted (8.4-6.0) to drive mosfet gate

http://www.mouser.com/ProductDetail/Analog-Devices/ADM660ANZ/?qs=sGAEpiMZZMtitjHzVIkrqYThiPHWFX9aAfsE1NTyhUU%3d

« Last Edit: September 10, 2014, 05:49:22 PM by david4500 »

Offline longwhiteclouds

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Re: Tact switch and mosfet transistor questions
« Reply #115 on: September 10, 2014, 02:13:51 AM »
Got something up and  running. Thanks for all the help. I will post pics when I figure out how to close the lid.

Offline XombyCraft

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Re: Tact switch and mosfet transistor questions
« Reply #116 on: September 10, 2014, 03:32:11 PM »
What minimum wattage rating should we use for the 10k/15k resistor across mosfet gate and source?  Tempted to sandwich an SMD resistor between the leads to tighten up real estate.

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #117 on: September 10, 2014, 04:04:05 PM »
You can do that, probably go as small as 0402 (1005 metric) if you want to, probably an 0603 (1608 metric) will fit nicely.

In some cases N-channel MOSFETs provide advantages over a P-channel, mainly high speed switching, but for a user power switch, you can find PMOS parts with similarly low on-state resistance eliminating the need for a voltage doubler.  The other option is to simply put the NMOS on the low side.  Either will eliminate the need for that part. 

Though if you want to use a high side NMOS for whatever reason, that's how to do it.  You can alternately use a high side NMOS driver which is a chip specifically designed for driving a high side NMOS switch.  Here's an example; http://www.linear.com/product/LTC1981

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #118 on: September 10, 2014, 04:31:31 PM »
http://www.mouser.com/ProductDetail/Analog-Devices/ADM660ANZ/?qs=sGAEpiMZZMtitjHzVIkrqYThiPHWFX9aAfsE1NTyhUU%3d



What exactly is the charge pump doing in that config and why connected to batt positive on gnd.

My thoughts were it stops vdrop but then I looked at how its wired and I figure it wouldn't do that.  Maybe it does..

Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #119 on: September 10, 2014, 05:22:27 PM »
The input voltage is being doubled to drive the mosfet gate.

Normally connected, it inverts the input voltage. When wired as shown, basically backwards, it will work as a voltage doubler.

http://www.mouser.com/ds/2/609/ADM660_8660-243873.pdf

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #120 on: September 10, 2014, 06:25:38 PM »
Thanks
Page 8   Fig:8

What exactly is it doing that you cannot with just wiring off the batts?
Its benefit?  Does it open and close the fet better etc.,  reliability?
Yes I know drive a higher rds but with the fets Craig Break  and you  have posted and their low rds and ohms,  is it that bigger a benefit?

Uber curious cause that looks hecka cool  but ups the parts count..  :thumbsup:



Offline david4500

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Re: Tact switch and mosfet transistor questions
« Reply #121 on: September 10, 2014, 06:44:30 PM »
Mosfets with a higher Vgs Th (and hopefully lower Rds On) could be used. Did a quick search and this looks like it would work nicely: http://www.mouser.com/ProductDetail/International-Rectifier/IRFB7430PBF/?qs=sGAEpiMZZMshyDBzk1%2fWi5hvHeWgOih0blGzR0OIw98%3d Pg 1 Figure 1 in the data sheet

another: http://www.mouser.com/ProductDetail/International-Rectifier/AUIRFB8409/?qs=sGAEpiMZZMshyDBzk1%2fWi7r8jvGh7mrdq5g7UCjvCmQ%3d Pg 6 Fig 16


You're certainly correct, some of the mosfets posted here seem to have a low enough Vgs Th and Rds On that the charge pump wouldn't really be needed.

longwhiteclouds recently put together a mod with a PSMN1R9-40PLQ and had very good results:
"I'm getting 0.27 volt drop on a 0.3ohm coil with a little li-po charged to 3.8v"
http://www.reddit.com/r/OpenPV/comments/2fyjfu/whats_everyone_thoughts_on_this_mosfet_as_an/ckdzsof

With two parallel IRLB3034PBFs and two fully charged VTC4s, I was getting a 0.2 ohm coil dropping 0.3v, 0.6 ohm dropping 0.1v and 1.3 ohm dropping 0.05v.
« Last Edit: September 10, 2014, 07:57:20 PM by david4500 »

Offline Visus

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Re: Tact switch and mosfet transistor questions
« Reply #122 on: September 10, 2014, 07:20:33 PM »
Woot click in brain when read your post and then  the data
Rds On (Max) @ Id, Vgs   1.7 mOhm @ 25A, 10V

So the closer to 10v the better --  awesome understood

That mech is badarse ;hubba; and safe and should become a standard, no more stories of bad haps but darwin will still hand his beer to his buddy   
 

Offline longwhiteclouds

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Re: Tact switch and mosfet transistor questions
« Reply #123 on: September 11, 2014, 02:21:08 AM »
http://imgur.com/Ih6yoFk
http://imgur.com/Cbwz8Dj
http://imgur.com/fIFLetV
http://imgur.com/fJsTza0

I keep snapping legs of my mosfets trying to shoehorn them into a 1590g case with batteries so I made this while I wait for some prototype circuit board to arrive to do it properly(er). 

Online Breaktru

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Re: Tact switch and mosfet transistor questions
« Reply #124 on: September 11, 2014, 07:56:01 AM »
I keep snapping legs of my mosfets trying to shoehorn them into a 1590g case with batteries so I made this while I wait for some prototype circuit board to arrive to do it properly(er). 

Hold the leg with a long nose pliers as close to the body as possible before bending, keeping the leg at the base straight so it looks like this.....


Offline XombyCraft

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Re: Tact switch and mosfet transistor questions
« Reply #125 on: September 11, 2014, 12:39:30 PM »
Is there any way to determine the wattage requirement for the 10-15k resistor that goes between S and G on a mosfet?  I've got some SMD resistors that would fit nicely between the legs, but I'm not sure if they'd do the trick or not.

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #126 on: September 11, 2014, 04:03:01 PM »
Yes, you can.  Divide battery voltage by the resistance to get current.  Square it and multiply by resistance.  Or, you can square voltage and divide by resistance.  It's going to be a small number so you'll find that you can use pretty much any wattage rating you want.  Like I said, even the tiny 0402 parts with a 1/16W rating will be okay.  It's probably an 0805 that fits well, those are 1/8W.  The 0603 size is 1/10W.

BTW, that particular charge pump has an unusual wiring when configured as a doubler.  I thought it was hooked up wrong at first, but then looked at the data sheet and saw it was right.  It's designed mainly to be used as an inverter, but can be configured as a doubler by using a different wiring scheme.  That's probably why the wiring looked strange to you Visus.

It's generally easier to find low on-state N-channels than P-channels, especially in the leaded packages.  A doubler allows you to use one of those on the high side.  However, you can simply wire the part on the low side without the need for a voltage doubler.  In some cases, it can be handy to have your switch on the high side, but generally it's a moot point for a mod that does not incorporate a lot of electronics.

You're not gaining anything in gate-source voltage with a doubler.  A higher gate-source voltage is better for lower on-state resistance, but the gate-source voltage is equivalent when using a doubler on the high side versus using the switch on the low side.  There's nothing gained there.  However, you can use a tripler which will provide in increase in gate-source voltage for a high side NMOS such as the high side NMOS driver I linked to before.


« Last Edit: September 11, 2014, 04:37:06 PM by CraigHB »

Offline scripto23

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Re: Tact switch and mosfet transistor questions
« Reply #127 on: September 11, 2014, 04:53:39 PM »
Hi guys



Question about using a p channel



Wouldn't a N channel be better? (lower rds on)

Offline longwhiteclouds

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Re: Tact switch and mosfet transistor questions
« Reply #128 on: September 11, 2014, 05:04:24 PM »
Thanks again Craig. I will give that a try next time. Still not quite sure about this high side low side stuff.  If the fet is opening/closing the negative feed it is low side?

Offline XombyCraft

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Re: Tact switch and mosfet transistor questions
« Reply #129 on: September 12, 2014, 02:59:12 PM »
Yes, you can.  Divide battery voltage by the resistance to get current.  Square it and multiply by resistance.  Or, you can square voltage and divide by resistance.  It's going to be a small number so you'll find that you can use pretty much any wattage rating you want.  Like I said, even the tiny 0402 parts with a 1/16W rating will be okay.  It's probably an 0805 that fits well, those are 1/8W.  The 0603 size is 1/10W.

Sorry I didn't realize this was in reply to my post on the other thread.  Brain didn't process.  As it happens the 0805 SMD resistors i bought were 1/2W, and fit perfectly between G and S on the PMOSii I'm using.  Thank you for clarifying though, as always I really appreciate you taking the time to respond!

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #130 on: September 12, 2014, 04:46:28 PM »
If the fet is opening/closing the negative feed it is low side?

Low side is negative, high side is positive.


Offline MrFrizzy

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Re: Tact switch and mosfet transistor questions
« Reply #132 on: September 29, 2014, 11:17:29 PM »
Alright, so after referencing this page for the past few days and trying to get my head wrapped around the different specifications that MOSFETs have, I think I may have what I need to build the parallel box mod I want. I just need to know if either of these chips will be able to handle what I have in mind. They both should have a good turn on voltage threshold for single/parallel cells and a good drain-source voltage as well. My goal is to pretty much do whatever build I want on this box i.e. all the way down to below 100milliohms if need be (.1ohm).

https://www.fairchildsemi.com/pf/FD/FDD3706.html
This one is only rated for 50a and seems to only be available in SMD, but could I run 3 in parallel for a total of 150a capacity? What ill effects would I see with 3 in parallel? What about 2 in parallel?

http://www.mouser.com/Search/ProductDetail.aspx?qs=5XOdhvmYM0MZtKYUGpYp1Q%3d%3d
This one is rated at 150a. That is pretty much what I was looking for, but are there any downsides to using this chip?

ADDITIONALLY, these can be secured to the metal casing directly since they are N-channel mosfets, correct? Shouldn't that help with heat dispensation and therefore further reinforce the current ratings published?

Thanks a bunch!

- MrFrizzy


Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #133 on: September 30, 2014, 02:20:42 PM »
Both of those have good "on-state resistance versus gate-source voltage" charts for a single cell or parallel cells.  The Fairchild part has a lower threshold, though the NXP part is probably better.  It has lower on-state resistance and it has a maximum gate-source voltage of 20V versus 12V for the Fairchild part.  The NXP part would be better for either single or series cells.  Even though the Fairchild part has a lower threshold, you'll get considerably lower on-state resistance with the NXP part even as low as 3V gate-source voltage.

You can mount the tab to chassis ground and it will improve heat dissipation and the ability of the part to handle high currents.  If the chassis is a thermally efficient metal, it will make a large difference there.  It looks like the tab is electrically isolated for that NXP part.

You can parallel MOSFETs, but going with three of them brings rise to some derating issues.  Mainly it increases the amount of power required to transition the MOSFETs on and off.  If you are powering the gates through a low impedance source (like a tactile switch), it should not be an issue in terms of speed, but the current spikes can overload a tactile and burn out the contacts. 

There's a lot of capacitance with three gates in parallel.  There's a rush of current that runs in and and out of the gates when the MOSFETs are turned on and off.  Specifically, each of those NXP parts has 120nC total gate charge.  Three would make that 360nC which at 3V, is like a 100nF capacitor.  That can be a bit much for a tactile switch, they're not really rated for current spikes like that.

With such a low on-state of those NXP parts, you're getting switch resistance under an mOhm with two in parallel.  That's low enough to handle 40A without any issue.  In fact, if bolted to the chassis, two of them won't even warm up at currents quite a bit higher than that.


« Last Edit: September 30, 2014, 02:42:49 PM by CraigHB »

Offline MrFrizzy

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Re: Tact switch and mosfet transistor questions
« Reply #134 on: September 30, 2014, 04:01:53 PM »
That is exactly what I was looking to find out! I figured the tactile switch would have some troubles with paralleled MOSFETs in the long run, but I think I can make a larger momentary switch work in the looks department.

Another thing that I was looking at was the possibility to run USB charging boards in parallel. The one I had in mind was this. It uses the TP4056 chip. Could I use 1 usb port and create jumpers to tie the two boards together via the "In+" and "In-" holes? OR, is there another chip I can be looking at that has a higher charging current?

I have found these two pages, Linear Technology & Texas Instruments, that have many charging ICs that potentially will work. I also found this chip from TP Micro that sounds like it will do the trick as well. I'm not sure if I am missing anything or if there is anything in particular to look for, but I would appreciate all the help I can get!

Thanks!

- MrFrizzy
« Last Edit: September 30, 2014, 09:21:24 PM by MrFrizzy »

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #135 on: October 01, 2014, 07:11:20 PM »
There's two areas where charging rates are limited not including the maximal rate the batteries can tolerate.  First is the power connector and supply, secondly is the charger controller chip.

There's a good amount of power that a linear charger controller has to dissipate.  They work pretty much the same as a linear regulator with current limiting.  Like any linear regulator, it has to dissipate the difference in output voltage minus the difference in input voltage times output current.  That being the case, that little chip has to dissipate a worst case of 5V input minus 3V output (lowest battery voltage) times the charging rate.  So with a 1A rate, that can be as high as 2W, a lot for a small linear regulator.

You can get around that limitation by using a charger controller that employs a DC-DC converter.  Those conserve power aside from a small loss usually under 10%.  In that case, the charger controller can put out much higher currents.  There are charger controllers like that, not a wide range of them, but they are available.  They tend to be costly in both price and part count.  They reguire a larger PCB and have a larger number of supporting parts.

The other limitation is the supply and connector.  USB mini-B and micro connectors are limited in the amount of current they can handle.  You can remove that limitation by using a barrel type DC power connector.  The larger ones like the 5.5x2.1mm are rated for up to 6A.  Of course you also need an adapter that can support the current demand, not going to be a USB adapter since those typically don't go above 1A.  You can find them up to 2A, but you don't want to run one close to its limit if you can avoid it.

It should be possible to parallel USB charger controllers, though it would be a rather odd thing to do.  Odd as it is, I can't think of any reason why it would cause any functional issues.  You would need a separate connector and adapter for each charger or it defeats the purpose due to the limitation of the USB connector.  If you try to run 2A or more through a single connector, it will fail at some point, possibly not immediately, but it will fail.

Offline bob salter

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Re: Tact switch and mosfet transistor questions
« Reply #136 on: October 02, 2014, 08:11:25 AM »
How would I go about making an 8.4v REGULATED box mod? ie 8.4v whatever the charge in the battery?

Bob

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Re: Tact switch and mosfet transistor questions
« Reply #137 on: October 02, 2014, 11:29:59 AM »
How would I go about making an 8.4v REGULATED box mod? ie 8.4v whatever the charge in the battery?

Bob
That'd be two freshly charged lipos (4.2v + 4.2v = 8.4v) in series, but you'll get a nominal voltage of about 7.4v out of that, as lipos tend to stay around 3.6-3.7v for most of their usable charge.

If you want to keep it at 8.4v all the time, you'd have to use a booster board to force the voltage to stay around 8.4v and be regulated.

Or... and I kind of doubt anyone would recommend this, you could use a buck board and three lipos in series to regulate a nominal 11.1v down to 8.4v...  tricky and potentially lethal.

Offline MrFrizzy

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Re: Tact switch and mosfet transistor questions
« Reply #138 on: October 02, 2014, 12:28:39 PM »
There's two areas where charging rates are limited not including the maximal rate the batteries can tolerate.  First is the power connector and supply, secondly is the charger controller chip.

There's a good amount of power that a linear charger controller has to dissipate.  They work pretty much the same as a linear regulator with current limiting.  Like any linear regulator, it has to dissipate the difference in output voltage minus the difference in input voltage times output current.  That being the case, that little chip has to dissipate a worst case of 5V input minus 3V output (lowest battery voltage) times the charging rate.  So with a 1A rate, that can be as high as 2W, a lot for a small linear regulator.

You can get around that limitation by using a charger controller that employs a DC-DC converter.  Those conserve power aside from a small loss usually under 10%.  In that case, the charger controller can put out much higher currents.  There are charger controllers like that, not a wide range of them, but they are available.  They tend to be costly in both price and part count.  They reguire a larger PCB and have a larger number of supporting parts.

The other limitation is the supply and connector.  USB mini-B and micro connectors are limited in the amount of current they can handle.  You can remove that limitation by using a barrel type DC power connector.  The larger ones like the 5.5x2.1mm are rated for up to 6A.  Of course you also need an adapter that can support the current demand, not going to be a USB adapter since those typically don't go above 1A.  You can find them up to 2A, but you don't want to run one close to its limit if you can avoid it.

It should be possible to parallel USB charger controllers, though it would be a rather odd thing to do.  Odd as it is, I can't think of any reason why it would cause any functional issues.  You would need a separate connector and adapter for each charger or it defeats the purpose due to the limitation of the USB connector.  If you try to run 2A or more through a single connector, it will fail at some point, possibly not immediately, but it will fail.

It won't run at 2a, I read that they will actually put out about 850ma each so only around 1700ma total. My phone charger is rated at 1.8a and I haven't had any issues yet so i'm not too worried about burning things up. I think i'll give it a go and find out what happens, or purchase some of those chips and make a single board for the pair. The less ghetto looking I can make the box the better.  :yes"

You have been a great help Craig! Thanks! :beer-toast:

Offline Reckful

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Re: Tact switch and mosfet transistor questions
« Reply #139 on: October 02, 2014, 04:46:12 PM »
Sorry if this as already been posted but I was on break.

Here is plans for a unregulated 18650 box to give a little more details. Hope it helps. I know they sell them but they have the best diagram I have seen so far in regards to wiring.

« Last Edit: October 02, 2014, 04:55:26 PM by Reckful »

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Re: Tact switch and mosfet transistor questions
« Reply #140 on: October 02, 2014, 07:13:30 PM »
Sorry if this as already been posted but I was on break.

Here is plans for a unregulated 18650 box to give a little more details. Hope it helps. I know they sell them but they have the best diagram I have seen so far in regards to wiring.

FYI - That link seems to be dead.

Offline CraigHB

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Re: Tact switch and mosfet transistor questions
« Reply #141 on: October 02, 2014, 09:07:02 PM »
How would I go about making an 8.4v REGULATED box mod? ie 8.4v whatever the charge in the battery?

If you want to keep it at 8.4v all the time, you'd have to use a booster board to force the voltage to stay around 8.4v and be regulated.

There are no off-the-shelf boost modules I'm aware of capable of putting out 8.4 Volts at the currents required to power an atomizer.  So it's not really practical unless you are comfortable in designing your own boost converter.  There may be controller chips available with the required input and output range, but DC-DC converter design is quite tricky.  Not something to try without some formal knowledge of electrical design.

Quote
Or... and I kind of doubt anyone would recommend this, you could use a buck board and three lipos in series to regulate a nominal 11.1v down to 8.4v...  tricky and potentially lethal.

Actually, that would be my recommendation, use a buck module with 3 Series cells.  You can use whatever 3.7V cells you like provided they have the required drain limit.  Doesn't have to be a 3S LiPo.  The high drain LiPos can be hazardous if used without any protection.  However when protected, they're really no more hazardous than any other high drain Li-Ion battery.  The main problem with them is they are vulnerable to physical damage and can ignite quite violently when punctured.  You need to enclose them in a way that protects them physically.

There is some protection a buck module offers for over-current and short circuit, though it's never a bad idea to add a fuse inline for backup.  Most converter modules require some kind of reverse polarity protection so if using removable cells, you need that at least.

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Re: Tact switch and mosfet transistor questions
« Reply #142 on: October 02, 2014, 10:05:59 PM »
I was gonna suggest the 04050c but at 8.4v your double the bat so it should be fine up to at least 4amps but
being rated at 2.5A it won't be within specs.
It regulates up to 15v  with a hack 24v and using in my own part theory of reduced voltage @3.8-6.2v and  higher current its working a treat here  mine is stable at 7 amps with 18ga wiring with 22ga it was not..  This all depends on battery used.  It' will short/handle over 150Amps lol,  it is not short circuited protected so its one to be careful with..  Its almost impossible for us to hurt it but shorting it and your batts may not be..


Badarse and hugely overlooked but oh well .  lol

Fingers crossed over here but yeah its a nice booster but way way out of spec.  I have used it for a year now and still going great..
Check out Xomby post

Its tiny mon 

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Re: Tact switch and mosfet transistor questions
« Reply #143 on: October 02, 2014, 10:18:36 PM »
Oh okay, I thought that one topped out at 6V, according to the data sheet anyway.  If it can put out 8.4V without dying, then yes, it can be used for that. 

In any case, the series battery configuration will deliver the maximal current the module is rated for which can be as high 20A, higher in terms of burst limits.  The big advantage with the booster is it's single cell and a lot smaller, but greatly more limited in output current.

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Re: Tact switch and mosfet transistor questions
« Reply #144 on: October 03, 2014, 04:53:17 AM »
Here's a 50watt booster
you can run with series batts
lil biggums and gets warm @50 watts but if you wood mod it it will be probably be manageable..



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Re: Tact switch and mosfet transistor questions
« Reply #145 on: October 03, 2014, 05:03:05 AM »
Oh okay, I thought that one topped out at 6V, according to the data sheet anyway.  If it can put out 8.4V without dying, then yes, it can be used for that. 

In any case, the series battery configuration will deliver the maximal current the module is rated for which can be as high 20A, higher in terms of burst limits.  The big advantage with the booster is it's single cell and a lot smaller, but greatly more limited in output current.

Theres  a guy on ecf says he blew out resistors on it but I have not.  I wonder if he made a wiring mistake or such he blew them twice.
He was not using a pot and has it set for 4.8v..  I think he may have shorted it out too many times, he uses ss mesh builds on raidy's original genesis and that design is a short prone..  Meh' he post on here too, but I have not seen em in a while.. 

  Its trustworthy using Breaks build but at 8.4v not sure how many amps/watts it can handle there..

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Re: Tact switch and mosfet transistor questions
« Reply #146 on: October 03, 2014, 12:04:42 PM »
Here's a 50watt booster you can run with series batts lil biggums and gets warm @50 watts but if you wood mod it it will be probably be manageable.

That's like the crappiest converter you could build;

   It's asynchronous (uses a diode rectifier)
   It has a 65 mOhm internal switch (way too high resistance)
   It's current mode (less efficient)
   It uses bulk capacitors (takes up way too much space)
   It's built on a perf board (maximally lame)

Everything opposite of what I would do in building a converter.  I'm amazed he even got it to work. 

Though I've got to hand it to that guy, he makes the most complicated things sound simple.  He did it that way to show a booster in the most simple way possible so I understand the motivation, but not good for anything but a paper weight after being used as an educational tool.

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Re: Tact switch and mosfet transistor questions
« Reply #147 on: October 03, 2014, 12:57:23 PM »
That's like the crappiest converter you could build;

   It's asynchronous (uses a diode rectifier)
   It has a 65 mOhm internal switch (way too high resistance)
   It's current mode (less efficient)
   It uses bulk capacitors (takes up way too much space)
   It's built on a perf board (maximally lame)

Everything opposite of what I would do in building a converter.  I'm amazed he even got it to work. 

Though I've got to hand it to that guy, he makes the most complicated things sound simple.  He did it that way to show a booster in the most simple way possible so I understand the motivation, but not good for anything but a paper weight after being used as an educational tool.

 :laughing2:    :thumbsup:

But the internet said,

Ok another day spreading misinformation, I am getting good at that .   :yes"

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Re: Tact switch and mosfet transistor questions
« Reply #148 on: October 03, 2014, 02:40:08 PM »
I use the following as benchtop power supplies for testing:

1.23v to 30v buck @ 3A max
http://www.amazon.com/gp/product/B009HPB1OI/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

3.5v-35v boost @ 6A max (with on-board voltmeter)
http://www.amazon.com/VvW-Adjustable-Regulated-Converter-Voltmeter/dp/B00IOMST5O/ref=sr_1_6?s=electronics&ie=UTF8&qid=1412361364&sr=1-6

4v-30v boost @ 5A max (no voltmeter)
http://www.amazon.com/VvW-RRLM2587-3-5-30V-Converter-Regulator/dp/B00IOMSTOK/ref=sr_1_29?s=electronics&ie=UTF8&qid=1412361472&sr=1-29

as far as I can tell, they're all pretty accurrate, and i really haven't had any issues with them (using one as a power supply for a 12V PWM controlled fan, as supply for both the fan and the 556-based PWM circuit)
Potentially quickie mod boards...

Offline longwhiteclouds

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Re: Tact switch and mosfet transistor questions
« Reply #149 on: October 03, 2014, 09:01:46 PM »
My new 5000mAh beast. Thanks for all the help everyone. Without  Craigs wisdom and Davids parts lists it wouldn't have been possible.

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