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From: firstname.lastname@example.org (N. Thornton)
Subject: Re: powering a bulb or led(s) with audio amplifier?
Date: 27 Oct 2002 16:12:58 -0800
References: <3DB1323B.1F9EA4F0@stanford.edu> <email@example.com> <3DB929D1.F8551A8C@stanford.edu> <firstname.lastname@example.org>
NNTP-Posting-Date: 28 Oct 2002 00:12:59 GMT
email@example.com (carltons) wrote in message news:...
> In article ,
> firstname.lastname@example.org (N. Thornton) wrote:
> > "Bevan Weiss" wrote in message
> > > > brightness. so a simpler question: how do i hook up a bulb so as to
> > > > ensure the brightest peak light without damaging my amp? put the bulb and
> > > > a resistor - relative to the impedance of the speaker - in parallel with
> > > > the speaker?
> > We'd need to know power output and impedance of your amp.
> Incandescent bulbs vary in resistance depending on how much voltage is
> applied and how long it is applied. They have a positive temperature
> coefficient, which means that when cold they draw lots of amps and when
> they heat up at their rated voltage, they draw the correct amps to match
> their rating at a lower current than start up. Designing with a lamp is a
> royal pain.
I'm thinking that the lamp still wont exceed the amps current rating -
I hope. As long as its switched on at low vol and the knob turned up
all should be well. The lamp can be a tenth the R at low V and the amp
would normally acept that.
The only time you'd hit the trouble zone is if the amp was switched on
at full vol, then youd have a surge current in the bulb that could be
way past the amps abilities. Nearly all domestic stereos will handle
that, but an old 1970s one would probably roll over and die. So switch
on then volume up, and accept risk.
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