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From: bill@videovax.tv.Tek.com (William K. McFadden)
Newsgroups: sci.electronics
Subject: Re: Sine wave generator
Message-ID: <5486@videovax.tv.Tek.com>
Date: 21 Jul 89 19:49:14 GMT
References: <790@serene.UUCP>
Reply-To: bill@videovax.tv.tek.com.UUCP (William K. McFadden)
Organization: Tektronix TV Measurement Systems, Beaverton OR
Lines: 27

In article <790@serene.UUCP> gbell@pnet12.cts.com (Greg Bell) writes:
>I recently took on a somewhat dumb "home project".  I wanted to build a
>door-bell extension since the downstairs bell isn't audible from upstairs.
>
>The easy way to do this would be to put another doorbell in series (or
>parallel?) with the one downstairs.  I tried both ways, but neither worked. 
>Either one bell would ring, or neither.  But not both.

In series there would too little voltage to operate (e.g., 12v each instead of
24v).  In parallel they would probably have too little current (power xfmr
too small).  You can get this to work by doubling the voltage or current,
respectively.  I'd be in favor of doubling the transformer current and hooking
them in parallel, since the other solution uses higher voltages (e.g., more
dangerous).

>So, I thought it would be fun to build a simple circuit that would sense the
>drop across the xformer or bell downstairs and generate two sine waves in
>sequence, each decreasing in volume (ie. "Ding-dong").

I know this is cheating, but Radio Shack has a beeper that does this (ding-
dong, I mean, not sense the voltage drop).  You would still have the challenge
of designing the "voltage drop sensor."
-- 
Bill McFadden    Tektronix, Inc.  P.O. Box 500  MS 58-639  Beaverton, OR  97077
UUCP: bill@videovax.Tek.com,  {hplabs,uw-beaver,decvax}!tektronix!videovax!bill
GTE: (503) 627-6920         "The biggest difference between developing a missle
component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TI