I was asked to help someone with a halloween costume.... (vape thing into fog for FX purposes)
It uses a fish pump and a vape 'machine'? (I dont know official term..I dont smoke).. and some non-toxic fog oil...
I soldered everything up.. and using my bench top PSU at around 3v (it was a few days ago now.. but I believe it was just at 3v).. and it worked fine.
He wanted to add in the RF switching module so his wife could trigger it remotely..
Specifically this one:
In the tutorial he sent me to follow.. it uses this N-channel power MOSFET:
It was out of stock.. and I had an IRF740 laying around..
However.. when I tried to use it.. it doesnt turn on.
I thought perhaps the 3.7v battery (also used in this odd tutorial) wasnt powerful enough.. so I removed and powered it from PSU again.. (nothing).. I see the RF module V+ pin says 5v (not sure why they use a 3.7v battery?)
so I thought if I turn up the PSU a bit.. it will work.. it started to 'buzz'.. and spurt a bit.. but ultimately didnt work.
My initial thought was the IRF740 MOSFET wasnt opening fully?
datasheet:
I'm not always sure what to look at.. but does it say opens @2v and fully open @ 4v?
if so.. then what is my problem?
Thanks
edit:
Now I'm confused even more seeing this:
Is that saying it needs 20v to be fully open??
Vgs - Gate-Source Voltage: 20 V
Then I also read this:
The IRF740 is an N-Channel Power MOSFET which can switch loads upto 400V. The Mosfet could switch loads that consume upto 10A, it can turned on by provide a gate threshold voltage of 10V across the Gate and Source pin
I guess both allude to not having enough voltage to fully open it? (hence wrong MOSFET).