Hi!... Guys, can you help me design a JFET amplifier?.. I need to amplify the output of an IPOD so it can run a 1-watt speaker or maybe 2-watt speaker. Im having a hard time in finding the right JFET suitable for this audio amplifier.

I would like to know which should i use as IDSS and VGS: Is it the (min), (typ), (max). I dont really understand whats written in the specifications but i do know a little about designing the resistors RD and RS.

Please Help!... )

*Does anyone know what is the exact output signal of a full-volumed IPOD?*

THANKS!

 

Are you sure that you want JFET power amp ??
The power JFET are very rare transistors, not so easy to buy.

 

I have seen thousands of power transistors, hundreds of power Mosfets and hundreds of low power Jfets.
But I have never seen a power Jfet.

I found a Jfet power amplifier in Google. It used a power Jfet that is discontinued. The performance of the amplifier was not good.

 

Is there a specific reason you want to use a JFET over other discrete options?

Have you considered the "Amp on a chip" solutions?

 

Maybe the teacher said to design an amplifier with Fets. Then common ordinary Mosfets should be used, not odd Jfets.

 

Perhaps he has heard about recent developments in SiC power JFETS, developed for large SMPS use, e.g. by SemiSouth?

These would hardly be candidates for use in a 2W speaker amplifier, even if it were possible for him to get hold of any.

 

Instructions for a 2N7000 Amp

It shows all the steps for calculating a single stage MOSFET small signal amp. This is NOT a Power Amp, but gives you an idea what a design should 'look like' and how to read a datasheet.

 

I have seen thousands of power transistors, hundreds of power Mosfets and hundreds of low power Jfets.
But I have never seen a power Jfet.

I found a Jfet power amplifier in Google. It used a power Jfet that is discontinued. The performance of the amplifier was not good.

So, does this means i need to use a MOSFET? there are two mosfets that i know, d-mosfet and e-mosfet. Which should i use?...

Also, is there other any projects that uses JFET that is simple and useful? Please include its application. Ive been in this project for 1 week and i got stuck on what FET should i use.

 

I have seen thousands of power transistors, hundreds of power Mosfets and hundreds of low power Jfets.
But I have never seen a power Jfet.

I found a Jfet power amplifier in Google. It used a power Jfet that is discontinued. The performance of the amplifier was not good.

What are those "common ordinary MOSFETS"?

 

There are thousands of "common ordinary" Mosfets used as on-off switches but only a few used in power amplifiers to drive speakers.
Power transistors work better and easier in a power amplifier circuit.

www.redcircuits.com have a few Mosfet power amplifier circuits.