A couple of easy SHO/ or AMZ Mosfet questions.

[jimbob]

What Im trying to figure out is how much difference will I notice using a 5kb pot versus the required 5krev?

Also- I cant seem to find 9.1v zeners for the bs170 protection diode but I did find some 12v zeners. I assume the only difference will be the diode will protect the mosfet up to 12v compared to the 9.1? Or does this have to be 9.1v?

This question also applies to the AMZ mosfet booster, ect..as far as what value to use for the protection diode.

[PerroGrande]

The 12v Zener should be fine.

The gate-channel insulation on a MOSFET is about 20 volts "thick". As long as the protection diode is under this, you'll be fine.

Regarding the pot...

The 5KB pot will work fine.  The only difference between 5K-A, 5K-B, and 5K-rev is the taper -- in other words, the rate at which the pot changes resistance relative to the amount you turn the knob.    With a 5KB pot, the MOSFET boost tends to build most of its gain fairly late in the rotation of the knob.  While this is fine, it may make it more difficult to dial-in the amount of gain you want.

Check out RG's article called "The Secret Life of Pots" to get a handle on pot trim, and how you might be able to rig what you've got to work more like the reverse taper.

[jimbob]

With a 5KB pot, the MOSFET boost tends to build most of its gain fairly late in the rotation of the knob.  While this is fine, it may make it more difficult to dial-in the amount of gain you want.

Ah.. i noticed that.. Makes sense. Thanks