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Showing posts with the label BC 547B

VU meter

This circuit can control analog moving coil meters, for use as a VU meter. The circuit is left connected to the line terminals of the amplifier. VU meter works pretty simple. T1 and T2 increase the signal strength. The signal is then rectified by the two diodes and applied to the meter. The capacitors C3 and C4 ensure that the voltage is slightly flattened and the meter responds less quickly.  After building the circuit, it must be calibrated. For this purpose, the VU meter connected to a tone generator which delivers 0.3V at 1000 Hz. Then P1 is fully open, that is to say that the wiper of P1 is located at the entrance. Then P2 is so cut that regulates the meter full deflection. P1 is then adjusted so that meter reads 0.5 mA (= half the maximum).  For a stereo VU meter circuit to be built twice.
R1 = 1 MR2 = 820 ΩR3 = 2,2 kohmP1, P2 = 100 kC1 = 330 nFC2 = 22 uFC3 = 1 uFC4 = 470 uFT1, T2 = BC 547BM1 = 1 mA meter