PICO AD145, Руководство пользователя

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PPM or VU setting - A DIL switch controls this function and is shown on the above
diagram. When the switch is in its off position the meter follows a PPM characteristic
and in the on position a VU characteristic.
Meter illumination - A DIL switch enables the intensity of the meter back-light to be
altered. The factory setting is with the switch in the off position. It is recommended
that this setting is retained, because the higher intensity setting obviously increases
battery drain.
Main-output limiters - calibration involves two presets per output.
Using the 'L' output as the example …
Biasing and threshold are adjusted as follows: VR5 biases the limiter circuit to the
point of correct operation and VR4 sets the threshold. (Labelled SET 0 and THR
respectively.)
With no signal present, VR5 should be adjusted to give a reading in the
range
-1.5V to -2.5V at PIN 8 of IC 2.
VR4 should be adjusted to give a reading in the
range -2.5V to -3.5V at PIN 12 of IC2.
Apply a signal at 1kHz to the mixer to give a level of 0dBu at 'L' output. Then select
the limiter function and adjust VR5 until the output signal starts to fall (typically
0.2dB). The DC voltage at PIN 8 of IC 2 should be approximately -2.0V.
After setting VR5, adjust the output signal to just greater than +8dBu with the limiter
deselected.
Introduce the limiter and adjust VR4 until the output signal falls to
+8dBu. This is the THRESHOLD setting. (If a different threshold setting is required,
alter the signal levels accordingly.) The DC voltage at PIN 12 of IC 2 should be
approximately 0.6V different from that at PIN 8.
The right output can be set using the above procedure, but the preset and IC numbers
change to correspond with the output being calibrated.
The link function has no individual setting of its own. To ensure this works within
specification it is important that L and R outputs are set up as a pair. After following
the above procedure, the DC voltages at PINS 8 and PINS 12 of the ICs
should be identical.
(Tolerance

0.05V with typical figures at PIN 12 of -2.6V and
PIN 8 of -2.0V)
There are two DIL switches associated with the attack and release times: one for the
left output, the other for the right output.