Bosch Appliances Home Security System DS938Z User Manual

10  © 2012 Bosch Security Systems, Inc.

If the time period selected has elapsed from the last alarm, the LED will 

fl ash two times and the Trouble Output will activate.
Setting the Motion Monitor timer to shorter periods can be used to force a 

protection walk test of remotely located zones.
It is recommended that the 30 day timer be selected. This verifi es that the 

unit is operational and avoids nuisance trouble conditions caused by holi-

days, vacations, etc.

When attempting to remove any masking, many adhesives will either 

destroy the mirror surface or leave enough residue behind to reduce 

coverage performance.

AR8-13

AR8-13

D

4

3

2

1

4 3

1

2

5

A

B

P

C

E

F

G

H

I

J

N

O

K

L

M

A

B

C

D

E

F

G

H

I

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K

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P

TOP VIEW

M-4

M-3

M-2

M-1

E-1

E-2

E-3

E-4

5

SIDE VIEW

Figure 7.1: Mirror module to pattern reference

7  Optical Module
7.1 Optical Module Masking
Peel-off masks are provided with the unit for each segment of the opti-

cal module to allow for customized coverage, or to block out areas of 

objects that may cause thermal disturbances. The mask is self-adhesive 

and pre-cut in the shape of the optical module.
The location of the zone to be masked depends on the position of the 

detector. Therefore, determine the mirror surface to be masked before 

removing the mirror from the detector. 
To block out a particular zone or group of zones, peel off a section of 

the mask that corresponds to the appropriate zone, and stick it on the 

mirror segment. Before attempting any masking, be sure the chosen 

mirror surface is the correct one. Refer to Figure 7.1  to identify mirror 

segments and zones.

When disabling the look-down segment, do not mask segment 5 direct-

ly as this will disable the entire detector. Instead, mask the segment on 

the dome directly below segment 5.

 F.01U.263.663 | 01 | 05.2012 | 3

The DS938Z is a high performance passive infrared intrusion detector. It is 

equipped with advanced PIR detection and supervision circuits and is de-

signed to provide an alarm condition upon detection of an intruder passing 

through its area of coverage.
Employing balanced dual-opposed sensing elements, the DS938Z passive 

infrared (PIR) detector makes use of the fact that all objects give off (emit) 

infrared energy, and that the warmer an object is, the greater the amount 

of infrared energy given off. The DS938Z uses PIR receiver technology 

designed to detect the change in infrared energy caused when a target of a 

different temperature from a stable background passes through its fi eld of 

coverage.
The coverage pattern consists of sensor zones arranged to form a circular 

coverage pattern.
Using Motion Analyzer II circuitry, the detector must fi rst see a change in 

infrared energy in one zone followed by a change of energy in the remain-

ing zone. Therefore, disturbances that occur in only one fi nger do not 

constitute motion and are ignored. This “catch sensitivity” may be changed 

in the fi eld by the installer to provide the degree of sensitivity required by 

the installation.
Self-test and supervision circuits provide reliable operation in a variety of 

installation environments. The result is a highly advanced detector offering 

superior performance with freedom from false alarms.

Dimensions 

(HxDia)

3.5 in. x 5.25 in. (8.9 cm x 13.3 cm)

Input 

Power

6.0 to 15.0 VDC; 5 mA standby, 20 mA in alarm with LEDs enabled. Use only an Approved 
Limited Power Source.

Alarm Relay Silent-operating Form “C” relay. Contacts rated <100 mA, 25 VDC, 2.5W maximum, <20 

Ohm closed for DC resistive loads. 

Tamper

Contacts rated at 28 VDC, 125 mA maximum, <1 Ohm. Connect tamper circuit to a 24-
hour protection circuit.

Trouble 

Output

Maximum current load is 25 mA.

Optional 

Accessory

TC6000 test cord.