Re: simple protection for low wattage speakers?

From	Bill Sloman <bill.sloman@ieee.org>
Newsgroups	sci.electronics.design
Subject	Re: simple protection for low wattage speakers?
Date	2026-03-06 16:29 +1100
Organization	A noiseless patient Spider
Message-ID	<10odonl$dkva$1@dont-email.me> (permalink)
References	<87fr6fcwza.fsf@librehacker.com> <10oa73t$2lncl$1@ehsjr.eternal-september.org> <878qc6ci9t.fsf@librehacker.com>

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On 6/03/2026 4:12 am, Christopher Howard wrote:
On 6/03/2026 4:12 am, Christopher Howard wrote:
 >>
 >> parallel protection1    parallel protection2
 >> -+-[<D1]-[<D2]-+-       -+-[<D1]-[<D2]-[<D3]-[<D4]-+-
 >>   |             |         |                         |
 >> -+-[D3>]-[D4>]-+-       -+-[D5>]-[D6>]-[D7>]-[D8>]-+-
 >>
 >
 > Thank you, would you mind please explaining a little more about these
 > parallel protection circuits, i.e., how the protection works?

It's depressingly simple-minded. The current through a silicon diode is 
an exponential function of the voltage across it.

https://en.wikipedia.org/wiki/Shockley_diode_equation

typically 0.6V of voltage drop  gets you about 10mA of current. Add 
another 60mV and you get ten times as much current.

Stick two strings of diodes in parallel with your load, one string to 
limit the positive voltage swings and the other to limit the negative 
voltage swings, and if you apply an over-high voltage, the bulk of the 
current flows through the diodes rather than the load.

Get the data sheet for whatever diode you use and you can work out the 
rough numbers. Most diodes aren't all that tightly specified, but some 
are, and if you insist on using cheap diodes at least fix on a single 
part number and measure what they actually do. It is temperature 
dependent, but nothing all that dramatic.

-- 
Bill Sloman, Sydney

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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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