Weird title, but couldn't think of what else to call it. I want to build a clipping indicator that works in reverse of typical: instead of turning an LED on when clipping, it would turn the LED off. Don't even know if it's been done already.
I have a clipping circuit I've used a few times before, and hoping to modify it to work in this reverse function, I just don't know enough about electronics to do it.
I'm starting with the "Bilateral Clipping Indicator" circuit, published in The Audio Amateur 3/73 issue (article scan attached below):
I know this works for a single polarity:
But I don't know how (or if) that scheme can be applied to both polarities of the original circuit "bilateral" ness.
Can anyone help with tips and advice, steer me in the right direction, or even a better circuit than the one I'm working with?
Thanks!
I have a clipping circuit I've used a few times before, and hoping to modify it to work in this reverse function, I just don't know enough about electronics to do it.
I'm starting with the "Bilateral Clipping Indicator" circuit, published in The Audio Amateur 3/73 issue (article scan attached below):
I know this works for a single polarity:
But I don't know how (or if) that scheme can be applied to both polarities of the original circuit "bilateral" ness.
Can anyone help with tips and advice, steer me in the right direction, or even a better circuit than the one I'm working with?
Thanks!
Even when clipping, there are always zero crossings where the amplifier does not clip. So when you instantaneously turn on the LED at the moments when the amplifier doesn't clip, you only see it get somewhat less bright when the amplifier is driven into clipping.
Is that intended or should it turn off for a second or so when the amplifier clips for a few microseconds?
Is that intended or should it turn off for a second or so when the amplifier clips for a few microseconds?
Good idea Tom, thanks!
Inverting the input makes more sense that 2 inverted outputs as I was thinking. I'll model it & see how it works.
Good catch Marcel!
I hadn't considered the visual perception difference, and you're right, detecting it blinking off would be problematic without some type of "hold" circuit. It may not be as practical as I was hoping.
Thank you!
I'd probably implement a form of peak hold either way. Get the signal to a ground-referenced, logic-level signal and that becomes trivial, though you can do it in a pure analog fashion as well.
Tom
Tom
If you wanted to use a micro controller I'd look at the ATtiny85, 8 pin though hole seems perfect, no external parts needed, just a voltage divider at a ADC input pin and supply decoupling. You could program LED 'hold' time and peak values ether via software or set with external potentiometers. And maybe even DC protection. It also works with the Arduino IDE.
I appreciate all the comments and suggestions, but I've decided the "inverse" LED function is not a practical solution (thanks Marcel!).
Instead, I'm considering using a bicolor LED in normal "turn on" modes. One color (blue or white) on full time, the clipping LED (red) would simply change the perceived color. This should be far more visually detectable than my prior idea.
Thanks everyone!
Instead, I'm considering using a bicolor LED in normal "turn on" modes. One color (blue or white) on full time, the clipping LED (red) would simply change the perceived color. This should be far more visually detectable than my prior idea.
Thanks everyone!
C1 is 2 MF? Two megafarad. That's quite a bit. 😉 Is it supposed to be 2 µF or 2 mF (2000 µF)? Based on the other impedances in the circuit I'm thinking 2 µF.
Tom
Tom
That's similar to what I use. I have a bicolour LED with a green and a red LED chip. It's red when the loudspeaker relay is open, green when everything works normally and it turns yellow (red and green both on) for about 1 second when the amplifier clips.
I monitor the current ratio in the input differential pair, so the LED turns yellow whenever there is a large difference between the input and the feedback signals. If that happens too long, the output relay is switched off. See "Audio power with a new loop", Electronics World February 1996, pages 140...143, https://worldradiohistory.com/UK/Wireless-World/90s/Electronics-World-1996-02-S-OCR.pdf