simple protection for low wattage speakers?

From	Christopher Howard <christopher@librehacker.com>
Newsgroups	sci.electronics.design
Subject	simple protection for low wattage speakers?
Date	2026-03-04 08:42 -0900
Organization	A noiseless patient Spider
Message-ID	<87fr6fcwza.fsf@librehacker.com> (permalink)

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Hi, lately I've been playing around with making sounds on tiny 8-ohm
speakers — whatever units I could get for free, which included a 3W
speaker and also some 0.5 Watt and 0.25 Watt speakers. I feed in a small
signal, from my signal generator or from my analog computer, into my
LM386 amplifier (20x gain) and then to the speaker. However, several
times now I have accidentally pressed the wrong button on my signal
generator, or turned the knob too much on my analog computer, and blown
out the speaker. For example, the 3W-8ohm speaker should only see 5V but
I accidental drove it up over 10V.

So I was wondering about adding some kind of limiting circuit right
before the speaker. My understanding is that one way to do this is to
have back-to-back zener diodes, shunting excess voltage to GND. I am
unclear if that by itself is sufficient, or if I need resistors or
something to keep the diodes or amplifier from getting damaged. I
suppose another idea would be to have some kind of limiting right before
the amp, but I am not sure of the simplest way to go about that, with
voltage input being in the 100s of millivolts or less.

-- 
Christopher Howard

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simple protection for low wattage speakers? Christopher Howard <christopher@librehacker.com> - 2026-03-04 08:42 -0900
  Re: simple protection for low wattage speakers? ehsjr <ehsjr@verizon.net> - 2026-03-04 16:10 -0500
    Re: simple protection for low wattage speakers? Christopher Howard <christopher@librehacker.com> - 2026-03-05 08:12 -0900
      Re: simple protection for low wattage speakers? Bill Sloman <bill.sloman@ieee.org> - 2026-03-06 05:31 +1100
        Re: simple protection for low wattage speakers? "Edward Rawde" <invalid@invalid.invalid> - 2026-03-05 13:44 -0500
          Re: simple protection for low wattage speakers? john larkin <jl@glen--canyon.com> - 2026-03-05 12:06 -0800
      Re: simple protection for low wattage speakers? ehsjr <ehsjr@verizon.net> - 2026-03-05 17:34 -0500
        Re: simple protection for low wattage speakers? Jeff Liebermann <jeffl@cruzio.com> - 2026-03-05 20:09 -0800
          Re: simple protection for low wattage speakers? Jan Panteltje <alien@comet.invalid> - 2026-03-06 05:41 +0000
          Re: simple protection for low wattage speakers? john larkin <jl@glen--canyon.com> - 2026-03-06 06:56 -0800
            Re: simple protection for low wattage speakers? ehsjr <ehsjr@verizon.net> - 2026-03-06 14:26 -0500
              Re: simple protection for low wattage speakers? john larkin <jl@glen--canyon.com> - 2026-03-06 11:43 -0800
              Re: simple protection for low wattage speakers? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-03-06 19:46 +0000
                Re: simple protection for low wattage speakers? ehsjr <ehsjr@verizon.net> - 2026-03-06 17:56 -0500
          Re: simple protection for low wattage speakers? ehsjr <ehsjr@verizon.net> - 2026-03-06 14:08 -0500
            Re: simple protection for low wattage speakers? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-03-06 19:43 +0000
              Re: simple protection for low wattage speakers? john larkin <jl@glen--canyon.com> - 2026-03-06 11:58 -0800
      Re: simple protection for low wattage speakers? Bill Sloman <bill.sloman@ieee.org> - 2026-03-06 16:29 +1100
  Re: simple protection for low wattage speakers? Jeremiah Jones <jj@j.j> - 2026-03-04 13:20 -0800
  Re: simple protection for low wattage speakers? john larkin <jl@glen--canyon.com> - 2026-03-04 14:17 -0800
  Re: simple protection for low wattage speakers? "Edward Rawde" <invalid@invalid.invalid> - 2026-03-04 19:58 -0500
    Re: simple protection for low wattage speakers? Martin Brown <'''newspam'''@nonad.co.uk> - 2026-03-05 10:30 +0000
  Re: simple protection for low wattage speakers? Don Y <blockedofcourse@foo.invalid> - 2026-03-04 18:58 -0700
  Re: simple protection for low wattage speakers? "Edward Rawde" <invalid@invalid.invalid> - 2026-03-04 21:55 -0500
  Re: simple protection for low wattage speakers? Jasen Betts <usenet@revmaps.no-ip.org> - 2026-03-07 02:44 +0000

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