Would this MOSFET work for small switch/touch switch?

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TomCatt

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Excuse me, I'm electronically challenged :D

Would this MOSFET work for a touch switch / low amp switch? If ya got a minute, could you explain what is needed in a mosfet for this use?

TIA

ETA:
What are the practical differences between a p-mosfet and an n-mosfet? (Just think of this as helping one of those less fortunate victims of modumust fever :D.)
 
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Java_Az

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Excuse me, I'm electronically challenged :D

Would this MOSFET work for a touch switch / low amp switch? If ya got a minute, could you explain what is needed in a mosfet for this use?

TIA

ETA:
What are the practical differences between a p-mosfet and an n-mosfet? (Just think of this as helping one of those less fortunate victims of modumust fever :D.)


That would work For a single battery for stacked batteries you might want to go with something rated a bit higher. That mosfet is pretty small though so not going to be the easiest to solder. There is a few threads in here somewhere that has some good info on touch switches. Really all you have to do is add a pull up or pull down resistor from gate to source to make sure they turn off after you take your finger off the touch pads.

N channel is used for switching negitive. P channel is used for switching Positive. The P channel uses a negitive voltage on the gate to turn it on and the Nchannel uses a Positive. Thats pretty much the difference in the two.
 

nicotime

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TC..I have used this one both in touch switch mods and all of my mods with a tact switch for almost a two years now and I have not had any problems with it. Its small but not too small to solder. Here is a pic of it on a quarter..the one on the right.
P1020440.jpg


MOSFET N-CH 40V 42A I-PAK - IRLU3114ZPBF
 

TomCatt

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Thanks nico (+1 on the karma for you too ;)). What ohm (ohmage? :D) do you use for the pull up/pulldown (challenged remember) for this? I've used the IRL3103 on the one touch switch that I made and used 30Mohm following suggestions here.

I'm not an innovator like you and Java and others; but, you know what they say - imitation is the sincerest form of flattery :D.


ETA: Oh yeah, btw, what's the one on the left? :)
 

AttyPops

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The idea with the resistor is to pull it to a ground state, and not leave it possibly "floating" when you cut the power to it (lift the finger off the touch switch). The 30M ohm will probably work just fine. It needs to be high ohm so that when you pull the pin high, it's doesn't short out. As long as there is a connection to ground it out, the electrons will flow and it will be pulled low when off.
 

nicotime

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Thanks nico (+1 on the karma for you too ;)). What ohm (ohmage? :D) do you use for the pull up/pulldown (challenged remember) for this? I've used the IRL3103 on the one touch switch that I made and used 30Mohm following suggestions here.

I'm not an innovator like you and Java and others; but, you know what they say - imitation is the sincerest form of flattery :D.


ETA: Oh yeah, btw, what's the one on the left? :)

Thanks...need all the good karma I can get! Innovator...ha...I just throw stuff together until it makes smoke. :laugh:

Yep...like AttyPops said..around 30Mohms is good...I tried from 10M to 100M and I didnt notice much difference...other than the price...when you get over 30M the price gets up there.

The other mosfet is an IRF8736PbF...its bear to solder though.
MOSFET N-CH 30V 18A 8-SOIC - IRF8736PBF
 

TomCatt

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Thanks...need all the good karma I can get! Innovator...ha...I just throw stuff together until it makes smoke. :laugh:

Yep...like AttyPops said..around 30Mohms is good...I tried from 10M to 100M and I didnt notice much difference...other than the price...when you get over 30M the price gets up there.

The other mosfet is an IRF8736PbF...its bear to solder though.
MOSFET N-CH 30V 18A 8-SOIC - IRF8736PBF

Another +1 on the karma, nico! :D I actually started with 10M on the touch switch and then saw on here where someone (I think Dalton, but wouldn't bet the farm on that :?:) put 3 10M in series to get a more sensitive response. So, I clipped, added a couple more 10M and did help. This was with the 3103 so don't know if there's sumthin' diffrent with that'un compared to your mossy.

(Lookit me, making up words so it looks like I actually know sumthin'! :lol:. If you can't dazzle with brilliance and all that ;))
 

nicotime

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:laugh: Hey...you had me convinced!

I dont know if you have seen this before but there was a lot of good info on the touch switches here...it may be outdated by now but it may help.

http://www.e-cigarette-forum.com/forum/modding-forum/90438-touch-switch-building-info.html

I gave up on them because I have a bad habit of resting my trigger finger on the button. I even put one contact on the opposite side of the other contact and I still did it. :facepalm:

Once you get it set up make sure you meter it to see if you have any residual current when it should be off...and definitely put a master kill switch on it.
 

TomCatt

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+3 karma, nico ;). I had seen that a while ago; but not since I started fiddlin' with touch switching. BTW, the offsite link you provided....didn't even feel any air as that went past :D.

I have a touch switch Puck that I've been using for a month or more and have gotten used to not resting my finger on the contacts.


touch switch Puck.jpg
 
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