Hello,

I have a p-channel JFET, NTE 326, and I'm wondering if the source and drain are reversible on this particular FET? I've seen datasheets for
this and NTE gives the pinout ID, but they don't say if it is reversible nor do they give a symbol indicating this. Does anybody know?
If not reversible, what are the chances I've damaged the FETs?
PS. I'm operating in the ohmic region.

Thanks

 

Can you please elaborate on what you mean by reversable?

hgmjr

 

Hi Hgmjr,

Some JFETs, such as the MPF102, are made so that the source and drain are interchangable. It does not matter how it is wired into a circuit, it will work the same either way. Other FETs cannot be wired with the source and drain reversed. I think I have wired my p-channel NTE326 with the source negative and the drain positive, which is wrong. NTE datasheets do not say if this FET's source and drain can be reversed or not. If not, I'll have to rewire the FET to correct the connections and hope I haven't damaged the FET when I tested the circuit.

Thanks

 

I have never heard of any FETs being reversible.

How much current did you push "backwards" into the FET?

 

Hello Retched,

Some people say most if not all FETs are reversible, but I've read that some are and some are not. They have different circuit symbols too.
See pic.

The NTE 326 can take 9 mA. I went up to 8 mA with only about 1 volt Vds, or thereabouts. It was only for a few minutes.

Thanks

 

Most if not all Jfets are made symmetrically so that their drain and source can be swapped and they work exactly the same.

 

Huh! good to know.

All these years and I never knew that.

 

I too believe that JFET devices as a general rule can have their source and drain reversed as long as you take that into consideration when biasing the gate.

hgmjr

 

Thanks hgmgr
Thanks audioguru
Thanks audioguru