This linearized Darlington anemometer circuit supports a 4-20 mA current mode output. Adjust R10 to calibrate 4 mA (zero fpm), R11 to calibrate 20 mA (250 fpm)

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Other Materials from the Main Document

• Article «Solid state airflow sensor with linear 4-20mA output»
• Figure 1. This graph shows the power dissipated vs air speed of a TO-92 held at a constant 31 °C above ambient P_W = 31/Z_T
• Figure 2. This linearized Darlington anemometer circuit supports a 4-20 mA current mode output. Adjust R10 to calibrate 4 mA (zero fpm), R11 to calibrate 20 mA (250 fpm)
• Figure 3. This graph details Q1 power dissipation vs collector current. P_W = 5 V·I - I²R3
• Figure 4. This graph's data relates anemometer output vs airspeed: F_PM = 15.6(I_OUT - 4 mA) ±10 fpm