Another switch question?

[Stacis]

I was thinking for doing a dual fire button box with a MOSFET but the button are in series. So that both of them have to be pressed to fire. I was going to use the switchs from a bunch of computer power button. Or off old electronics. The question is what is a good MOSFET? And where to place it? With this build I want to uses parallel 26650 and make the battery sled also hold 18650.

 

[BlueridgeDog]

Putting your switches in series would require them to be both on to fire.

 

[Stacis]

Yes that is what want to do. So both have to be press to fire. The question is the MOSFET do I need one for each switch or just at the last switch?

 

[twgbonehead]

You put the two in series, and then use a single MOSFET - the switches in series will then drive the gate of the fet to turn it on. (From a circuitry point of view, look at a single-switch design, and replace the single switch with 2 in series).

Great idea, by the way, having a built-in "safety" for the mod!

Recommending a particular mosfet is difficult, since you don't say what power levels (particularly what current levels) you are looking for.

 

[Stacis]

I am still working alot of details out in my head. Most of the brain farts happen at work while driving. I was thinking of a key switch as a gag mod for a friend today but one idea at a time to draw up the wood box sizes then source the supplies. I am trying to use alot of what I am doing with junk I have. (I scrap metal) or get for free. I just read that there are MOSFET in atx power supply. I saw some what looks like resettable fuses one a motherboard. And I have lots of tec switch to play with. I just have to cross reference a lot of part numbers .

 

[dc99]

Save yourself a ton of headaches and just use the IRLB3034. If your going to drive it super hard you can parallel two. Just a suggestion.

 

[Stacis]

What is the advantage of dual MOSFETs?

 

[Mooch]

It divides the current between the two, reducing how hot they get. You only need to do this at higher current levels though. Especially if you use a low-resistance MOSFET like the IRLB3034.