Help with my first mosfet build

[GMayberry]

I have never used a mosfet before and would like some advice on how to do it simply, but properly. Which ones to get, resisitors needed or not, etc etc. I have been reading and reading, but everyone seems to have different ideas in mind. All I want to accomplish is the smallest 18650 box mod possible, with a visually appealing button. I could go simple with a mechanical style switch, but again, small and appealling is desired. Btw, single 18650, not dual.

Thanks in advance for any help, advice, links, and even pictures!

 

[GMayberry]

Would this be a good starting point? Sorry for the ignorance to this matter, that is exactly why I am asking. I have no idea about these!

10 x IRF9540 IRF9540N "IR" Power MOSFET P Channel 23A 100V USA Seller | eBay

 

[GMayberry]

Ok.... so 65 views and no responses? Is my question that stupid?? lol

 

[twgbonehead]

That's an old, p-channel FET with a high RDS.

This would be better (among the thousands)
http://www.nxp.com/documents/data_sheet/BUK9612-55B.pdf

 

[GMayberry]

Thank you! Will I need resistors with this as well? Again, I am sorry for the ignorance, but I just want to get one under my belt the proper way. First time dealing with one and want it done right!

 

[JimmyDB]

That's an old, p-channel FET with a high RDS.

This would be better (among the thousands)
http://www.nxp.com/documents/data_sheet/BUK9612-55B.pdf

Vgs is 10V?

 

[Mike_S]

Vgs is 10V?

They're just giving you an example of the Rds value at a Vgs of 10V. It will still turn on with a much lower gate voltage and at a lower drain to source current, but the value of Rds on will be higher. Check Fig. 6 in the datasheet.

OP- resistors aren't necessary, but it wouldn't hurt to use a high value pull down resistor on the gate to make sure the mosfet is fully off when the switch is open.

 

[GMayberry]

They're just giving you an example of the Rds value at a Vgs of 10V. It will still turn on with a much lower gate voltage and at a lower drain to source current, but the value of Rds on will be higher. Check Fig. 6 in the datasheet.

OP- resistors aren't necessary, but it wouldn't hurt to use a high value pull down resistor on the gate to make sure the mosfet is fully off when the switch is open.

But if I put a hard switch for on and off it would be ok right?

Could someone post a drawing of how the circuit would look to make sure I am thinking right? I have no way to post one until later tonight. I am thinking the positive goes from battery to hard switch, hard switch to MOSFET, MOSFET to fire button, fire button to 510. And obviously the grounds. Is this correct?

 

[Visus]

But if I put a hard switch for on and off it would be ok right?

Could someone post a drawing of how the circuit would look to make sure I am thinking right? I have no way to post one until later tonight. I am thinking the positive goes from battery to hard switch, hard switch to MOSFET, MOSFET to fire button, fire button to 510. And obviously the grounds. Is this correct?

Really good mosfet discussion, you get advice on the best mosfet in the market for our use and pictures..

Tact switch and mosfet transistor questions

 

[Kahuna]

this might help, dont forget to put a master kill switch on the negative side.