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The circuit at Electronics-Lab is an Instructable with some errors:
1) It doesn't have a peak detector circuit at its input so the LEDs will be a dim blur.
2) It uses two 1.2k resistors but doesn't show where the second one goes. Does it replace the 7.5k resistor on the datasheet? Then the LEDs will be dim and the signal must be 2.5V peak which is too high.
I hadn't seen that one. The few project I found with Google has a transistor to handle input. However I don't have a convenient transistor cross reference, and BC series transistor isn't exactly readily found locally. Could I get away using 2n3904 or 2n3906 instead of BC series?