Capacitive displacement transmitter circuit

Published:2011/3/24 1:30:00 Author:Joan | Keyword: displacement transmitter , Capacitive displacement transmitter | From:SeekIC

Circuit principle: the multivibrator signal is led out by D2 output. When D2 output is high, the monostable circuit is in a steady state, and D3 output, D4 input, D5 output are low voltage. When D2 output is low, the monostable circuit enters into the temporary stable state. When D3 outputs high voltage, it charges Cx through R3 and RP. Meanwhile, D5 outputs a high level into the U-I output stage, and D4 input voltage decreases exponentially with time. When the voltage is lower than D4 threshold level, the output jumps high, and then jump into a low voltage after being inverted by D5. When the square wave D2 outputted jumps high, Cx is then discharging through R3 and RP until D2 becomes high voltage, which completed a one-shot cycle. Waveform in each point is shown in Figure 2. The output pulse width td is proportional to Cx. The voltage, smoothed by R4 and C2, sent to VT base, is amplified and converted into 4 ~ 20mA DC uniform signal.



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