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| Clipping Indicator. Opamp as window comparitor, thougts and improvements. |
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| stian:
@Audioguru ok so you suggest i add in a peak detector. A full blown peek detector for both the pos&neg periode i think is a bit overkill. I can see it will improve alot. But i was thinking that there must be a much simpler way to reduce the "flashing" of the leds. also a xenon bulb i dont have. I was thinking, cant i just toss in some caps over the leds?. I test this in Ltspice and it seems to work fine. The dip on the leds are now just around 2mA instead of a full 12mA on each trigger. |
| Yansi:
Window comparator of what against what? You can not compare the output signal of an amplifier with a fixed reference window. As I have already pointed out, you need to compare against the instantaneous supply voltage of the amplifier and respect the saturation voltage drop across the output stage, which is mostly independent of the supply rail voltage. |
| stian:
Yansi. i appreciate your feedback very much. but i don't understand why you say it will not work. Ok so, i might not have explained myself good enough. "as usual". Im not trying to see if the output signal of the amplifier is clipping. i want to check if the input signal will clip. If i have a Input signal (NOT OUTPUT), that swings MAX between 6v-12v and 6v-0v (12vpp max). Now this will cause clipping on the signal due to that the opamp has a VOH = Vcc - 1.5v and VOL = 20mv Any input signal above 10.5 will cause clipping if vcc = 12v. So knowing that the signal will start clipping at 10.5V i can use this window comparator to set the trigger levels right? Also, the DC offset if adjustable. now if i set the offset to example 8V , and the signal in is example 6V in. there is about 0.5V of clipping on positive period. Hope this clarify my intentions a bit better. |
| Audioguru:
What is the signal source that has a very high level of 10.5Vp-p and you want to detect when its voltage exceeds 10.5Vp-p and its offset voltage? It is not a 3Vp-p audio signal. A clipping detector is always used at the output of an audio amplifier, never at its input because an audio amplifier has plenty of voltage gain. Its output produces clipping, not its input voltage. |
| JS:
--- Quote from: Audioguru on June 18, 2018, 01:33:03 am ---What is the signal source that has a very high level of 10.5Vp-p and you want to detect when its voltage exceeds 10.5Vp-p and its offset voltage? It is not a 3Vp-p audio signal. A clipping detector is always used at the output of an audio amplifier, never at its input because an audio amplifier has plenty of voltage gain. Its output produces clipping, not its input voltage. --- End quote --- Not always, you could overdrive the input stage or you can measure the input signal and know how much signal will be at the output. Also, asymmetrical clipping doesn't mean DC offset, it could be an asymmetrical signal with thin high peaks on one side and wide low ones in the other (seen in signals with even harmonics) JS |
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