Dynamic scanning spectrum display

As shown, it
consists of band-pass filter, rectifier integration circuit, dynamic scanning circuit, comparison amplifier circuit and LED matrix.
    The input part of the circuit uses 2 four-op amp circuits to form 8 band-pass filters. The input full-frequency signal is divided
into eight segments. It sets the center frequency of the eight segments based on the relationship between 2 and 4 octaves. Set at 32№, 76Hz, 180№,
430Hz, 1.05kHz, 2-SkHz, 6kHz, and 14.5kHz.
    Dioi~D1.06, R40l~‰¨‰l~ island are connected to the output ends of each band-pass filter.
The rectifier integration circuit of each frequency band is used to convert the amplitude of the AC signal output by each filter into the level of DC level. After selection by
the analog switch, it is sent to the DC level comparator and drives the LEI through the matrix circuit) Luminous display.
    IC6, Scorpion and R50l-Rsos form a level comparator. Among them, Rsoi~R50a form an eight-level voltage divider.
After dividing the 12V DC voltage according to a certain proportion, it is added to the inverting terminals of eight voltage comparators as the reference voltage of each comparator
. It can be seen from the figure that these 8 reference voltages are higher than one from bottom to top. The DC signal voltage sent out after being gated by the analog switch
is simultaneously added to the non-inverting input A terminal of each voltage comparator (IC6, IC) for
comparison with its respective reference voltage. When the input DC signal voltage is higher, then From the bottom up (that is, from IC7d to ICr5a), the more interesting comparators
output high levels and light up the corresponding LEDs. According to the number of lit LEDs,
the strength of the signal in that frequency range can be known. R600 - R608 in the picture are current limiting resistors and are used to protect the D of the operational amplifier.