Casella CEL CEL-368 - Manual (Page 34)

put signals can be accepted from other sources for example the CEL-
3025 mentioned above, and when a CEL-216 Line Adaptor is used, AC
input signals with a maximum level of 22.5 V
pk-pk can be fed in from a
tape recorder.
The user can switch the 200 V polarizing voltage OFF. This allows an
electret microphone such as the MK-250 to be screwed on to the pream-
plifier in place of the standard condenser unit. The MK-250
1 ⁄
2 " Electret
Microphone is more robust than the condenser microphone and being
less influenced by damp conditions is more suitable for long term envi-
romental measurements made out of doors.
CEL-368 - Type 2
The standard microphone supplied with the CEL-368 (Type 2) is a CEL-
230 Microphone and Preamplifier Unit. This consists of a
1 ⁄
4 " diameter
pre-polarised electret microphone capsule permanently attached to a
low noise preamplifier which plugs into the tapered end of the sound
level meter. The characteristics of the microphone satisfy the require-
ments for both free field (IEC standards) and random incidence (ANSI
standards).
The microphone and preamplifier unit can be used remote from the in-
strument when it is connected to the sound level meter via an extension
cable. C4493/5 (5 m), C4493/10 (10 m), and C4493/20 (20 m) are stand-
ard cables, and a maximum length of 100 m can be delivered.
The preamplifier supplies 30 dB or unity gain, and conditions the output.
Input signals can be accepted from other sources. For example, if a
CEL-3025 Vibration Attachment is used with a CEL-225/3 (or CEL-225)
Preamplifier instead of the normal CEL-230 Unit, vibration measurement
can to be undertaken with input signals from an accelerometer. Simi-
larly, when a CEL-316 Line Input Adaptor is used in the preamplifier con-
nector, AC input signals with a maximum level of 22.5 V
pk-pk can be fed
in from a tape recorder.
4.5 Analog Section
Page 30 - CEL-268/368 Operator's Handbook