winner10920:
How's this link work for a shematic, seem correct to you? http://www.cadvision.com/blanchas/hexfet/npch-sw-sch.htm
im gonna use an irf9520 I think i and an irf 540
My plan to drive it is from a 555 timer, im gonna set up a dual supply opamp to take the 555 output from 0/12v to -12/+12,
That schematic is for slow-speed switching rather than PWM - you need to reduce those 10k resistors between gate/source so the MOSFETs turn off fast - with 10k they are likely to spend 20 to 200us in turn-off, all the time in the linear region dissipating lots of power. For a 5kHz signal this clearly isn't sensible. Remember power MOSFET input capacitances can be around 10nF or so. To switch off in 1us you might need the gate-source resistors as low as 100 ohms (which would mean using 2W resistors!)
Proper MOSFET driver chips use active drive to the gate rather than one-sided in order to get good switching speed both on and off.