![]() |
Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
|
In Reply to: Re: Opamp class A bias using FET - how to calculate resistor value? posted by Saurav on May 3, 2002 at 12:17:27:
First, PICK A FET. The best FET in this case should have a somewhat lower Idss, maybe 10 ma or less. However, almost any FET will work. It is OK to use a pot, but 10K is too high. Try to use a 2K or lower pot, so that you can get better resolution.
This is the easiest way: Get a 9V battery and some clip leads. Use the 9V battery as your test voltage source. wire up a test assembly with the fet, pot, and add a 100 ohm resistor between the DRAIN of the FET and the (+) terminalof the 9V battery. Of course, connect the pot with the wiper of the pot connected to the input of the pot to make it a variable resistor. Put the pot between the source and the gate of the FET. Make the GATE of the FET, that is now connected to the pot, the most (-)V part of the circuit, by connecting it to the NEGATIVE TERMINAL of the 9V battery. Put the multimeter ACROSS the 100 ohm resistor and adjust the pot until you get .3V across the 100 ohm resistor as this is 3Ma.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Re: Opamp class A bias using FET - how to calculate resistor value? - john curl 13:26:27 05/03/02 (10)
- Re: Opamp class A bias using FET - how to calculate resistor value? - Saurav 13:47:19 05/03/02 (9)
- Re: Opamp class A bias using FET - how to calculate resistor value? - john curl 14:53:48 05/03/02 (8)
- Re: Understood. Thanks for your help (nt) - Saurav 15:01:08 05/03/02 (7)
- Is my site on the porn list AGAIN? - cfraser 15:15:39 05/03/02 (6)
- Re: Is my site on the porn list AGAIN? - Saurav 15:25:27 05/03/02 (5)
- Re: Is my site on the porn list AGAIN? - cfraser 15:53:38 05/03/02 (4)
- Re: Is my site on the porn list AGAIN? - john curl 17:15:24 05/03/02 (3)
- Re: Is my site on the porn list AGAIN? - Saurav 17:34:53 05/03/02 (2)
- You'll have to change your moniker - cfraser 20:17:56 05/03/02 (1)
- Re: Good point :) (nt) - Saurav 09:02:57 05/04/02 (0)