Internal circuit structure diagram of LM3914

Internal circuit structure diagram of LM3914

shown. This circuit can be used in situations where humidity detection and indication is required.
    There are 10 voltage comparators in the LM3914 as drivers for 10 light-emitting diodes. The reference voltage of each voltage comparator is
provided by a series resistor divider circuit, and its voltage value decreases from top to bottom. The humidity signal detected by the humidity sensor Icl is passed through R. , RP1,
as a control signal input from the ⑤ pin of IC2, output through the buffer amplifier, and added to the reverse input terminals of 10 voltage comparators. When
the reverse input voltage of the comparator is greater than the voltage of the non-inverting terminal of the comparator, The comparator outputs a low level and the corresponding light-emitting diode lights up. The higher the voltage output from the buffer amplifier in
    LM 3914 to the inverting end of the voltage comparator
, the more diodes will light up. When the voltage is higher than the voltage at the non-inverting end of the comparator connected to pin ⑩ in the figure, all 10 light-emitting diodes in the circuit will light up. Light up.