Definitely not. Looks like you're mixing up depletion mode and enhancement mode, that is another story, has nothing to do with N-MOS or P-MOS.
Yes you're right, I was lol. Apologies.
Definitely not. Looks like you're mixing up depletion mode and enhancement mode, that is another story, has nothing to do with N-MOS or P-MOS.
Yes, R3 limits the base current, which is required for a BJT.I guess R3 limits current, while R4 ensures that Q1 receives proper voltage?
I think I understand now.If you need a high side switch, why don't you use a p-channel MOSFET?
View attachment 51703
Gotcha.Yes, R3 limits the base current, which is required for a BJT.
R4 is mainly to absorb any base leakage current and insure it stays fully off, especially if the device experiences higher temperatures.
That's fine.Since it's being used in the marine environment, I'd like to add tinned blade connectors and encase the whole thing in epoxy.
I forgot to include a protection diode in case the load has some inductance to absorb any negative transient when it is turned off.
Revised schematic below:
View attachment 51709
With the optocoupler, you likely don't need Q7.this is what I've come up with including the optocoupler.
Why should a NPN transistor work but not the switch?I don't think it will work in my situation, but I think the NPN will.
Why the optocoupler? Replace Q? by the switch and resistor as shown in my post #16.
Why should a NPN transistor work but not the switch?
...depending upon the gain the of opto, you may need to reduce the value of R2 or increase the value of R1, to fully saturate the opto output transistor when its ON.
I'm not familiar with simulators but it seems to work?
Yes.At 12V, I'm unsure how it is affected, but I expect it is based on the brightness (power) of the octocoupler LED.
I simulate just about all circuits before I built them.I'm not familiar with simulators but it seems to work?
If the long wire from the switch to the MOSFET catches noise that interferes with the operation of the MOSFET, so will the same noise interfere with the operation of a driving transistor and thus finally the MOSFET.I believe your idea won't work because the switch is located physically far away from the circuitry.
You believe wrongly. It definitely will work.In your example, I believe the switch must be between the two resistors to activate the gate. It definitely works just not for this application.