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Elmo SERVO AMPLIFIER DBP SERIES User Manual

Page 91

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90

DBP - Rev 6/93

HF Filter (R195, R196, C61, C62)

The function of the HF filter is to reduce the amount of noise present on

the signal inputs to the 2S82, reaching the Phase Sensitive Detector and

affecting the outputs. Values should be chosen so that

15Kohm < R195=R196 < 30Kohm

160x10

3

C61 = C62 = ------------ (pF)

R195 x fr

fr = Reference frequency in KHz

R195 in Kohm

This filter gives an attenuation of 3 times at the input to the phase

sensitive detector.

AC Coupling of Reference Input (C60)

Select C60 so that there is no significant phase shift at the reference

frequency. That is,

10

6

100 x R192

C60 = -------------- (pF) Rx = ------------ (Kohm)

fr(KHz) x Rx 100 + R192

R192 in Kohm

If Rx yields less than 50K, install a value of Rx=50K in the C60 equation.

Maximum Tracking Rate (R201)

The VCO input resistor R201 sets the maximum tracking rate of the converter

and hence the velocity scaling as at the maximum tracking rate, the velocity

output will be 8V.

Decide on your required maximum tracking rate, "T" , in revolutions per

second. Note that "T" must not exceed the specified maximum tracking rate or

1/16 of the reference frequency.