hello everyone, I'm now making a Buck converter with tlc555 ocillator.
But there's a problem with using nmos as switch.


The left part is ocillator and the right parts is buck converter with capacitors in parallel(to increase capacitance).
I have to use nmos as switch but that connecting method doesn't work.

I refer to The Art of Electronic 3/e.
I used that method for connecting but doesn't work.


How do I connect N channel mosfet to function correctly?


I have 2N7000 and IRFZ44N.
I use regulated DC power supply as input.

 

You need a P-channel MOSFET (and a Schottky diode, and an inductor)

 

Hi ex,
If your power lines for the bread board are as I believe, then the 2N7000 Source pin is at +Vs.

Also, when driving a tungsten lamp, the initial current will be approx 5 times the normal operating current, so you may be damaging the 2N7000.
E

 

"In order to help another effectively, you must understand what he understands.
Instruction begins when you put yourself in his place so that you may understand what he understands and in the way he understands it". Soren Kierkegaard

That’s very good. I see so many threads where we spend two or three pages trying to reach that point.

 

Just FYI. The high side gate driver is designed to overcome the problem of using an N channel MOSFET as a high side switch.