From owner-freebsd-chat Mon Oct 28 13:33:23 2002 Delivered-To: freebsd-chat@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8690E37B401 for ; Mon, 28 Oct 2002 13:33:22 -0800 (PST) Received: from testmail.wolves.k12.mo.us (testmail.wolves.k12.mo.us [207.160.214.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0114243E6E for ; Mon, 28 Oct 2002 13:33:22 -0800 (PST) (envelope-from cdillon@wolves.k12.mo.us) Received: by testmail.wolves.k12.mo.us (Postfix, from userid 1001) id F15AD1A951; Mon, 28 Oct 2002 15:33:15 -0600 (CST) Received: from localhost (localhost [127.0.0.1]) by testmail.wolves.k12.mo.us (Postfix) with ESMTP id ECF681A947; Mon, 28 Oct 2002 15:33:15 -0600 (CST) Date: Mon, 28 Oct 2002 15:33:15 -0600 (CST) From: Chris Dillon To: Dag-Erling Smorgrav Cc: Soeren Schmidt , Ronald G Minnich , <"."@babolo.ru>, David Nicholas Kayal , Subject: Re: Show me the light In-Reply-To: <20021028125820.I35504-100000@duey.wolves.k12.mo.us> Message-ID: <20021028152422.E36084-100000@duey.wolves.k12.mo.us> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Mon, 28 Oct 2002, Chris Dillon wrote: > > You don't need a DAC, you just connect each data pin to the output > > through an appropriate resistor. Google for "covox schematics". > > Right, I know, thats exactly what I made. I just realized I never > had any diodes in the thing, just resistors. It was just a resistor > ladder. You aren't getting 8-bit resolution out of that, though, > and it is not a PCM DAC. My own memory does me a dis-service. You're absolutely right, the way those resistor ladders are designed, you really do get a rough equivalent of an 8-bit PCM DAC. I forgot that I had used lower to higher resistances for the MSB through the LSB (respectively), which would do the trick just about right. For some reason I was remembering that each bit carried an equal weight (which is certainly possible to do, just wouldn't work well at all in this situation). -- Chris Dillon - cdillon(at)wolves.k12.mo.us FreeBSD: The fastest and most stable server OS on the planet - Available for IA32 (Intel x86) and Alpha architectures - IA64, PowerPC, UltraSPARC, ARM, and S/390 under development - http://www.freebsd.org No trees were harmed in the composition of this message, although some electrons were mildly inconvenienced. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message