[ List Subjects ][ Main Page ]
[ View Followups ][ Post Followup ]

Date: 08/24/00 at 11:06 AM
Posted by: Wayne Shanks
E-mail: wshanks@wilcoxon.com

In Reply to: Re: Simple charge amplifier posted by John Dunn - Consultant on 07/19/00 at 2:35 PM:

a charge amp can be made simply with a op-amp

Rf
| ----/\/\/\/\-------|
|--------| |- ------|
| Cf |
| | \ |
|-----CX---------|- --- |- \ |
| | \____|_____Vout
=== | /
== |------|+ /
- | | /
|
===
==
-

I hope the ascii art comes out ok
Cx is your piezo crystal

Vout is Qin/Cf

the low frequency limit of this circuit is set by 1/(2*Pi*Cf*Rf)
the high frequency limit is set by the unity gain bandwidth of the op-amp * Cf/Cx

you need to put this in a grounded metal box.. any movment of the wires, air breezes,
or stray electric field will be picked up by the circuit .

Wayne

Follow Ups:

Post a Follow-up:

Name:
E-Mail:
Subject:

Message to Post: