The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: John Woodgate
Subject: Re: Output Impedence
Date: Fri, 25 Oct 2002 18:49:22 +0100
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Fri, 25 Oct 2002 18:54:39 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that news.cable.ntlworld.com
wrote (in ) about 'Output Impedence', on Fri, 25 Oct 2002:
>How would I go about getting the output impedence of a computer sound card.
Do you mean the load impedance? Unless you can find any information from
the manufacturer, assume that the minimum value is 8 ohms.
If you mean the internal impedance:
Reproduce a fixed-frequency sine wave. Start with 1 kHz. Set the output
voltage about 0.5 V below clipping level (use an oscilloscope) with an 8
ohm resistive load. Measure the output voltage as precisely as you can.
Remove the load and measure the output voltage again. It should be
slightly higher. If the output voltage with 8 ohm load is V volts, the
output current is V/8 amps. If the *change* in output voltage is Vc
volts, the output source impedance is 8Vc/V ohms. Repeat at 100 Hz to
see what happens at lower frequencies and at 8 kHz to see what happens
at high frequencies.
Why do you want to know?
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
PLEASE do NOT copy news posts to me by E-MAIL!
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup