| 摘要 |
The present invention belongs to the field of the tuning of musical instruments, particularly pianos, and is aimed at improving accuracy and stability whilst providing economical, lightweight and compact equipment. It is characterised by a Frequency/Voltage conversion using two identical channels: a reference channel and a signal channel, from which the two outputs are applied to a differential amplifier connected up as a voltage comparator. The means for visually indicating the tuned condition may be a centre-zero pointer galvanometer or two LEDs or two ordinary lamps or a single lamp. Chief application: production of visual electronic tuners for pianos and all musical instruments. <IMAGE>
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