Electronic musical instrument tuner - compares instrument frequency with internal standard giving optical indication of beat note using LEDs

摘要

The electronic tuning indicator is for musical instruments and operates over a range of nine octaves. Signals from the instrument are picked up by a microphone (14) and fed to an amplifier (15) and pulse shaper (16) from which they are used as clock signals for the flip-flop (17). In the flip-flop, the instrumental signals are compared with those from a multivibrator (3) followed by a frequency divider (8) with octave selector (9). With zero beat between the signal from the instrument picked up on the microphone and the locally generated reference frequency, one of two light-emitting diodes (18, 19) lights up. With non-equality, the two diodes light alternately at a rate equal to the frequency difference.