The following settings and modifications were done for the OPO Servo-filter to the original Servo-filter which electronic schematics and bill of material are saved on the wiki.
1-Setting of switches on the front panel:
* The differentiator shall be disabled on the front panel in setting the switch on "OFF".
* The switch INV/NON INV on the front panel, shall be set on INV.
2-Setting of the 8 straps on the board:
Low-pass filter, Notch filter 1 and notch filter 2 are activated on the board in setting strap on connectors P7, P8 and P9 (3 pins) between pins 1 and 2
* The transmission signal is positive with a peak at 1.26V.
It shall be inverted: the strap on connector P4 (3 pins) is set between pin 2 and 3.
The threshold level must normally be tuned to a negative level of 600mV (THRESHOLD OUT).
We had also to increase the sample-hold capacitor (C89). See below.
* Strap is set on connector P11 (3 pins), between pins 2 and 3, in order to activate the sample-and-hold on the triangular signal, on the locking.
* Strap is set on connector P3 (2 pins) to connect the triangular signal to the output stage.
* Strap is set on connector P2 (3 pins), between pins 1 and 2, for test purpose.
To check low-pass filter, notch 1 and notch 2 filters (in scan mode) between TEST IN and TEST OUT. For this test the differentiator, shall be set on "ON" (not intuitive but important). After this test, the differentiator shall be disabled the front panel in setting the switch on "OFF".
* Strap is set on connector P1 (2 pins), in order to be able to tune the offset.
3-Modification of components:
* Integrator 1/f: corner frequency changed to 3.3 kHz
Capacitor CMS 1206: C38 = 22nF
* Integrator 1/f2: corner frequency changed to 220 Hz
Capacitor CMS 1206: C26 = C33 = 330nF
* Low-pass filter: cut-off frequency changed to 3.3 kHz
Capacitor CMS 0805 : C45 = 2.2nF (0805)
Resistor CMS 1206 : R59 = 22k
* Notch filter 1: notch frequency changed to 10.5 kHz / quality factor changed to 6 (measured)
[Capacitor CMS 0805 1% : C49 ; C50 ; C51 ; C53 = unchanged (560 pF)]
Resistor CMS 1206 : R65 ; R66 ; R67 ; R68 = 27k
Resistor CMS 1206 : R73 = 820
* Notch filter 2: notch frequency changed to 14.2 kHz / quality factor changed to 6 (measured)
[Capacitor CMS 0805 1% : C60 ; C61 ; C62 ; C63 = unchanged (560 pF)]
Resistor CMS 1206 : R79 ; R80 ; R81 ; R82 = 20k
Resistor CMS 1206: R89 = 820
* Gain adjustment (G): Gmin = 0.125 / Gmax = 05 / Gtyp = 1
No modification.
* Modification of he sample-hold capacitance on the triangular signal:
Capacitor 1206 of 4.7microFarad added on the 1microFarad capacitor (C89).