下面是[红外线水位计电路]的电路图

材料BOM表：

R1 10K 1/4W Resistor
R2,R5,R6,R9 1K 1/4W Resistors
R3 33R 1/4W Resistor
R4,R8 1M 1/4W Resistors
R7 10K Trimmer Cermet
R10 22K 1/4W Resistor
C1,C4 1µF 63V Electrolytic or Polyester Capacitors
C2 47pF 63V Ceramic Capacitor
C3,C5,C6 100µF 25V Electrolytic Capacitors
D1 Infra-red LED
D2 Infra-red Photo Diode (see Notes)
D3,D4 1N4148 75V 150mA Diode
D5 LED (Any color and size)
D6,D7 1N4002 100V 1A Diodes
Q1 BC327 45V 800mA PNP Transistor
IC1 555 Timer IC
IC2 LM358 Low Power Dual Op-amp
IC3 7812 12V 1A Positive voltage regulator IC
RL1 Relay with SPDT 2A @ 220V switch
Coil Voltage 12V. Coil resistance 200-300 Ohm
J1 Two ways output socket