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发表于 2009-12-8 10:06:59
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"In this case,The D1's Vf is change wtih Q1's Ibe+Ice,so you said "D2 may be eliminated as well, depending on the fan motor spec."
But now i want to raise Q1's Ve to reduce the Vout's voltage range , Would you give me some good advice?"
if you look at the output voltage as a function of the input voltage, you will notice that the circuit's gain is determined by R3/R2+1. so increasing R3 or decreasing R2 changes the gain.
In this particular circuit, the output *VOLTAGE* across the motor is proportional to the temperature sensor.
you can also reconfigure the circuit so that the output *CURRENT* is proportional to the temperature sensor. |
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