RE: TI-H: speaker

To: "'ti-hardware@lists.ticalc.org'" <ti-hardware@lists.ticalc.org>
Subject: RE: TI-H: speaker
From: Jan Zumwalt <zumwalt@alaska.net>
Date: Mon, 1 Sep 1997 13:28:21 -0800
Reply-To: ti-hardware@lists.ticalc.org

-----Original Message-----
From:	Thayne Miller [SMTP:yomaster@geocities.com]
Sent:	Monday, September 01, 1997 6:51 AM
To:	ti-hardware@lists.ticalc.org
Subject:	RE: TI-H: speaker

I think I figured out what's wrong.  The red/white wires are normally at 5
volts, right? Well, to make a tick (or a short sound), the red/white wires
have to be turned NEGATIVE! This means that when the + side of the speaker
is on ground, and the red/white wires are on -, the ONLY way to make sound
is to make the red/white wires more negative than ground, thus current
flows from ground to red/white. This is why I think it is IMPOSSIBLE (well
it is still possible...but not the way they tried to do it before) to make
a transistor amplifying speaker, unless you can make the battery switch
around every time you want a tick!

[Jan Zumwalt]  This being the case, you might want to go to a small opp
amp. They thrive on a negative swinging voltage. I have not checked yet,
but several of my industry magazines have advertised single voltage opp
amps. I would assume that a good one could be run on a 9v battery.

Has any body already tried/recommend a 1 watt single voltage opp amp?

Thanks, Jan Zumwalt

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