2
BLN-95-8938-5
BRIDGE NETWORK SHEMATIC
389B
Schematic of the KE02901, 2 Bridge Network Used in Slope Applications.
TECHNICAL DATA
OPERATING VOLTAGE
11 to 15 Volts dc
POWER CONSUMPTION
3 watts maximum
SENSOR EXCITATION
The KE02901, 2 Oscillator-Demodulator provides 1.5
Volts RMS at 400 Hz into a 10 ohm load such as the
primary of the Danfoss KS10201 Level Sensor.
SENSOR INPUT
The voltages across the two isolated windings of the
inductive sensor should be equal at null. With a change of
transducer position, the voltage of one winding should
increase as the voltage of the other decreases. No
voltage should fall below 1 Volts RMS nor rise above 15
Volts RMS. In a typical application using the Danfoss
KS10201 Level Sensor, the output voltage of the sensor
at null is approximately 4.4 Volts RMS.
ERROR OUTPUT VOLTAGE
An increase of 0.075 Volts across terminals E and F and
a corresponding decrease of 0.075 Volts across
terminals C and D results in and error signal of 80
millivolts output across terminals J and N. When the
KS10201 Level Sensor is used error output voltage
changes a nominal 80 millivolts per 1% slope error.
THEORY OF OPERATION
The KE02901, 2 Oscillator-Demodulator obtains 12 Volts
dc from the amplifier it is connected to. The system is
made up of two basic sections, the Oscillator and the
Demodulator.
OSCILLATOR
The Oscillator runs on a regulated 6 Volts dc. An internal
circuit supplies two signals 180° out of phase to a power
H configuration of four transistors. The transistors flip-
flop the signal, alternately putting a positive and negative
signal on two wires which connect to the microsyn
sensor.
DEMODULATOR
Refer to the Bridge Network Schematic. The microsyn
inductive sensor generates an ac signal in each of its two
secondaries, which are coupled to the bridge network. A
pair of full-wave bridge rectifiers convert the ac signal to
dc. The dc voltage charges two capacitors, whose ratio of
voltages is compared to ratio of voltages determined by
the remote setpoint potentiometer. Any difference
between the two ratios (the error signal) is then
transferred to the amplifier. In control applications, the
remote setpoint potentiometer determines the desired
operation slope. In steering applications, the steering
feedback potentiometer is connected in place of the
remote setpoint potentiometer. Varying the
potentiometer setpoint changes the bridge ratio and calls
for a new null point for the sensor.