4
Testing and Adjustment
(Note: Please see connection diagrams on the following pages.)
Connect your servo to the servo header. Make sure you properly orient your servo
connector with the header. The header is marked with “Y R B”, where Y is for
Yellow, R is for Red or positive, and B is for Black or Negative. (Colors for the
yellow wire will vary by servo manufacturer, but the Red and Black are usually
there.)
Supply power to the board through either the barrel connector (P6) . You should
see the “PWR” LED light up as soon as power is applied.
Adjust the threshold level, “LVL” pot (R18) clockwise until the “LVL LED” turns on
and then stop the adjustment. Then, adjust the “Jaw Max” pot to set the maxi-
mum you would like the jaw to open. Adjust the “LVL” pot back until the “LVL
LED” turns off. Then, adjust the “Jaw Min” pot until the jaw closes to desired po-
sition when no audio is playing.
Finally, adjust the “LVL” pot until the “LVL LED” is on and then back it off just a
little until the “LVL LED” turns back off.
This is a critical adjustment is very sensi-
tive. Turn the pot slowly and in very small increments.
This control is used to adjust how loud the sound needs to be before the servo
will start to move. If it is set too low the servo will remain at its maximum position
too much of the time. If it is set too high the servo will not respond to the sound
at all or not as much as desired.
Audio can be fed to the circuit from a line-level source (MP3 player, CD player, or
one of our CAR/P or CAP audio boards).
Using a Line Level Audio Source
Feed audio to the circuit through the 3.5mm stereo “Audio In” jack. If you want both
channels of sound to control the ST-400 then make sure that the red shorting jumpers
are on RChnl and LChnl. If you want only the right channel to control the ST-400 then
remove the shorting jumper from LChanl and make sure a red shorting jumping is on
RChnl. If you want only the left channel to control the ST-400 then remove the short-
ing jumper from RChanl and make sure a red shorting jumper is on LChnl.
