Looking at a few examles and guides as such, https://www.electronics-tutorials.ws/transistor/tran_7.html and https://electronics.stackexchange.com/questions/67343/mosfet-as-a-switch,
The control voltage LOW should turn OFF the load and control Voltage HIGH should enable the load. However, in both cases load remains unchanged? Is there anything wrong? Note that MOSFET threshold is set to 1V .

 

hi Z,
If I am reading your circuits correctly, you are shorting the 12V to 0V.!!!!
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I was under impression that everything should be connected to a common ground? Where should I connect the negative side of +12V supply?

 

Hello,

When you want to switch the lamp X1, then it should be in series with the mosfet.
Place the lamp X1 between de Drain of the mosfet and the +12 Volts.

Bertus

 

Please note another odd thing I have come across.




Note the voltages after the switch. How can I have 2.5V after the switch if the switch is open? Shouldnt it be 0V?

 

By placing the light bulb in series with the mosfet as bertus suggested, the bulb is permamently off despite the switch status.

 

hi,
How have you determined the N MOSFET specification.?

Try an actual MOSFET model?.
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What is the difference between using a single MOSFET to drive a higher voltage and the following circuit? :



I think this simulation software is a bit shit
I am adding a picture of MOSFET specs - it doesnt help me much.

 

hi z,.
Are these circuits part of a college assignment.?
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BTW: the last two images are too small to read.

 

@zazas321 check your Q2 connections.

 

That is not a part of any assignment. I am trying to build a DALI controller for lightning and I require to control 18V with 3.3V logic. My apologies, let me upload the pictures again:



With this configuration, the lightbulb is also constantly ON and doesnt change if I press the switch

 

hi,
Check the orientation of Q2.!
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@zazas321 check your Q2 connections.

Yes I have flipped the Q2 mosfet the other way arround as shown in the example picture - now the lightbulb is permamently OFF .

 

What does the simulator measure of voltage on the Q2 gate?

 

I am measuring 12V when switch open and 11.75 when closed

 

hi,
How have you determined the N MOSFET specification.?

Try an actual real MOSFET model?.
E

 

Please see the specifications on the left if you can see it. Also, this is the only N type mosfet available on this application.

 

The IRF530 is not a 4.5V or 5V logic level N MOSFET, you can use a npn bjt to replace the IRF430, to add a Rb as 2.2K ~4.7K, and a Rbe as 10K.

 

Im not actually using IRF530 , im just trying to simulate any basic MOSFET switch.




I have swapped the first MOSFET with the BJT transistor and im trying to switch P type MOSFET. I have put loads on both sides as I was not sure which side do I need to use but it does not show any signs of life

 

For a P MOSFET that you should in series the load with D pin, and R1 can be higher as 4.7K, the Ic of npn bjt only needs less <10mA at here, Ib = Ic/10, so the Ib can be <=1mA.

Edit : You missed the Rbe, if there is no Rbe, when the S1 switch is OFF then the input will be as a floating status, the noise will be generates as a AC signal.