> The drive seems to be OK, certainly better rise/fall than without the > totem pole, although I do wonder about the gate not going to 0V, > only down to just below 1V, so maybe the FET isn't fully on Might be the 15V zener, as 16V - 15V =3D 1V. Though even -15V should be eno= ugh to=20 turn the FET fully on. The layout is a little strange with 9V and 16V supplies. Typically I guess = you'd want=20 the 15V zener to protect the gate of the FET, in which case it might make a= little=20 more sense if it were between gate and source, but not a big difference. It could be that I'm just not seeing it right, but what is the intention of= the seperate=20 16V supply for driving the gate? The FET is switching +9V, and being a P-Ch= =20 MOSFET gate needs to be -ve WRT Source to switch it on. As the shown the=20 output of the push-pull BJT arrangement will give you 0V and 16V, a gate-so= urce=20 drive of -9V for on and +7V for OFF. If anything there would be more advant= age in=20 increasing the drive for on state to -16V, and just 0V for off? --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .