Quote:
Originally Posted by XRPete
Ok, so i use an new grounding point in the car. and the 3 pin mosfet which i thought i blew, is reading at I (on) key position 11.89v @ top pin and 21.70v on the bottom give or take some mv's.
|
Some thoughts:
1/ I had just assumed you got things mixed up here, because while I got those voltages, my readings are reversed - 20v top pin, 11v bottom.
2/ Since it has popped it's possible the readings will be weird.
3/ That MOSFET is rated for +/-20v gate voltage (like many are).
4/ Mine only just exceeds the 20v maximum, so my repeated bench testing might not ever show the problem of the LCD dying.
5/ Yours is going well over! Typically, 10v is used in circuits, except for logic level MOSFETS that work on 3.3v-5.0v - so 20v is the max that should safely be passed into them.
6/ I think that MOSFET dims the display at night time, it's going to get hotter at that time, so it needs to be cooled.
7/ Jaycar don't have MOSFETs in the size you need, but there's a couple there which are larger (with the same +/-20v gate specs) which may work, except night time dimming will be an "unknown" because the board has been calibrated to work with a different one. I'd be looking at the IRF1405 - it has the same pinouts and I'd somehow add a small flat heatsink.
(That's enough thoughts.)