Chronoskop CHR-9 Timegrapher
User manual
www.CHRONOSKOP.com
11
3. Measurement with the Timegrapher
There are two ways to measure mechanical clocks using the time scale. There are:
•
Acoustic measurement
•
Measurement with the light barrier
During acoustic measurement the sound of the clock is detected. In the light barrier
measurement the light path of the pendulum is interrupted. The source of the measurement
(acoustic or optical) is to be set in the settings of the device.
3.1. Acoustic Measurement
Measurement with the built-in piezo microphone
The acoustic measurement can be realized with the built-in piezo microphone. To decouple
acoustic noise, the piezo disk is mounted on a 5 mm thick foam. For maximum decoupling
the device can be placed on an additional foam. Because of the high sensitivity of the
microphone (despite digital filtering), ambient noise should be avoided. The signal gain can
be adjusted with the rotary knob placed in the front wall of the device. For very quiet watches
it is recommended to remove the back cover of the watch for the duration of the
measurement. The use of the battery voltage can also help to avoid the noise from the
voltage network.
To measure a wristwatch or a small watch, place it on the microphone on the top of the
device. In order to optimally transfer the vibrations to the piezo crystal, the watch case should
lie directly on the microphone. This method is only allowed for watches up to 200 g! Although
the covering metal disk of the piezo element of the microphone is made of a soft metal, the
watch should be placed with care to avoid scratches.
Please note: Piezo discs are very sensitive. When measuring with the built-in microphone
you should even avoid the use of the display during the measurement, as this can generate
noise too.
