[sdiy] Simple clip detect LED circuit

[Magnus Danielson]

From: "Paul Perry" <pfperry at melbpc.org.au>
Subject: Re: [sdiy] Simple clip detect LED circuit
Date: Tue, 2 May 2006 09:20:40 +1000
Message-ID: <003301c66d75$dd5d0560$0a01a8c0 at frostwave>

> couldn't you just take the audio signal & amp it & drive
> a led directly via a resistor?
> You could just rely on your eye to do the smoothing.

Hmm... how does that work for lower frequencies? Not very well I am afraid to
say. It is quick and dirty, I'll give you that!

Actually, I am a bit sceptic about having half-wave rectifiers for peak/level
detection to start with, it assumes that the voltage level is the same both
positive and negative. It is for your test-generators sine, but not so much for
real life signals. (untintentionally) Phase-invert a drum or something, and you
get a large negative peak rather than a large positive peak, and the peak in
the opposite sign will most probably not be close to that level.

At least do a "dirty" full-wave rectifier, only the peak part of the waveform
needs to be more or less matching. Then, do a smoothing (for peak hold) of that
and drive the diode from that.

Cheers,
Magnus - who redesigned catastroph limiters for PA-systems with at least 8 speakers capable of 139 dB(SPL) each... yes, I care about peak detection!

> paul perry melbourne australia
> 
> ----- Original Message ----- 
> From: "Seb Francis"
> > I'm looking for a simple clip detect LED circuit.  I have in my mind
> > something like rectified audio signal into opamp/comparator, compared to
> > threshold voltage, driving LED & peak-hold capacitor via a diode.  Just
> > thought I'd see if there's a ready made circuit out there to compare to..?
>