![]() ![]() When using power supplies higher than 25V, the working voltage value of C5 must be raised to 35 or 50V.When using power supplies higher than 12V, the value of R10 must be raised accordingly.With TL072 or TL082 chips, current drawing is about 4.5mA and 13mA respectively. Using a TL062 chip at 9V supply, stand-by current drawing is about 1.5mA and less than 10mA when the LED illuminates. This Audio Clipping Indicator circuit was intended to detect clipping in preamp stages, mixers, amplifiers etc.In this way, the adjustment of R5 will be made easier. ![]() On the contrary, if the circuit will be used to detect only very low peak-to-peak voltages, it is convenient to lower R1 value to, say, 220K omitting C2. If you need to detect higher output peak-to-peak voltages, R1 value must be raised. With the values shown, the circuit can be easily set up to detect sine wave clipping from less than 1V to 30V peak-to-peak (i.e.C5 adds a small output delay in order to allow detection of very short peaks. The op-amps outputs are mixed by D1 and D2, smoothed by C4, R7 and R8, and feed the LED driver Q1 with a positive pulse. This technique allows to detect precisely and symmetrically either the positive or negative peak value reached by the monitored signal. The heart of the circuit is a window comparator formed by two op-amps packaged into IC1. The power supply can also be obtained from higher voltage rails provided suitable R/C cells are inserted. Obviously, the unit can be embedded into an existing mixer, preamp or power amplifier, and powered by the internal supply rails in the 9 - 30V range. Unfortunately, an oscilloscope and a sine wave frequency generator are required to accurately setup this circuit. This unit is particularly useful in signaling overload of the input stages in mixers, PA or musical instruments amplification chains, but is also suited to power amplifiers.Ī careful setting of Trimmer R5 will allow triggering of the LED with a wide range of peak-to-peak input voltages, in order to suit different requirements. This will help the operator in preventing severe, audible distortion to be generated through the audio equipment chain. is reaching the onset of its maximum permitted peak-to-peak voltage value before an overload is occurring. For IC based power amplifier, connect this circuit before the DC decoupling capacitor if any.This circuit was intended to be used as a separate, portable unit, to signal by means of a LED when the output wave form of a particular audio stage is "clipping" i.e. ![]() The amplifier output stage is illustrated as a pair of PNP-NPN transistors, but you can use this circuit for integrated circuit (IC) based power amp. To hold the display (for better visibility), C1 is provided make a short overload peak light the led for longer periods. Here is the schematic diagram of the circuit. This circuit will give visual indicator, the led will light, when the output reach 50Watt level (can be adjusted with R2 pot). Because our perception of slightly clipped signal might be inconsistent depending on our mood and our mental focus, providing a clipping indication will be very useful for those who responsible in sound performance. The problem is that some people might notice and some might not. Detecting severely clipped signal is easy by listening, but a soft clipping might be hard to detect. The cause of clipping can be different for various case, but most of them, especially in power amplifier stage, is because the amplifier is forced to serve out-range of power when the input volume is too high. Clipping is a condition where a signal is truncated by insufficient processing. ![]()
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