On 12/21/2020 3:04 PM, Scott Dorsey wrote:
wrote:
Scott Dorsey wrote:
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But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?
No. This is a "power-on thump" which is caused by the coupling capacitors
charging up, not the power supply.
** The OP never mentioned any " thump" and is not talking about one.
Yes, you are correct. From the original post, it seemed like he was using
a protection lamp on the speaker output (which is a common thing to do),
not on the AC line (which is also a fairly common thing for people to do
when they don't have a variac).
--scott
If you watched the video I posted, you'd see the
schematic is a very simple light bulb in series with
the "Hot" side of the AC line:
https://www.antiqueradio.org/art/DimbulbSketch.jpg
Yes, these are typically used when you don't have
a variac.
But audio turn-on "thumps" do not last a full
second! I stand by my theory that the initial in-rush
of current is the charging up of the electrolytic
filtering caps, on the outputs of the rectifiers.
But apparently, you are correct that light bulbs
are sometimes used in series with speakers, to protect
them:
https://trueaudio.com/st_prot1.htm