Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: 50 ohm termination
Date: Mon, 17 Mar 2025 23:35:36 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 30
Message-ID: <vrabk7$16env$1@dont-email.me>
References: <20250317190219.00001b76@dne3.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Tue, 18 Mar 2025 00:35:37 +0100 (CET)
Injection-Info: dont-email.me; posting-host="79869c7ff4dd25dc54df0bcf6f572015";
	logging-data="1260287"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18Ddq7S8rcXpFQy9BOHaVNb"
User-Agent: NewsTap/5.5 (iPhone/iPod Touch)
Cancel-Lock: sha1:TR6xJqfx233rEngPNMArdPhExho=
	sha1:rSZ4qzBI4cvrcZ9G+4wEEpPlxPY=
Bytes: 1830

Toaster <toaster@dne3.net> wrote:
> Can I get away with terminating the far end of a transmission line or
> do I need a series resistor at the source and a parallel resistor at
> the destination?
> 
> Thank you,
> Toaster
> 
> 

Depends. 

In general, when you just have one source and one load, with no taps along
the way, the best approach is to series-terminate the source. 

That is, you put a 50Ω resistor in series with the output connector, and
let the load be essentially an open circuit. 

The load sees the full signal amplitude, and there’s no huge power
dissipation. 

Anyplace in between, the waveform is more complicated. 

Cheers 

Phil Hobbs 

-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics