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Technical Description
4.15 Audio Dopplex (D920-P, D930-P), Mini Dopplex (D900-P)
The power supply regulates the battery voltage and provides 5V dc to the microcontroller and
all circuitry apart from the audio power amplifier which is supplied directly from the battery.
The power supply is activated by the on/off switch. The supply is firstly turned on by the on/off
switch and then the microcontroller takes over and keeps the power supply on, turning the
supply off when the auto shut off time has elapsed or when the on/off switch is depressed a
second time.
Power Supply
On/Off
Switch
Microcontroller
Battery
Low
Monitor
PSU
Reset
Split rail
Generator
Battery
Display
Waveform *
Output
Probe *
Identification
Zero *
Crossing
Detector
ANR
Soft
Limiter
Audio
Amplifier
Supply
Ground
P
ro
b
e
C
o
n
n
e
c
to
r
Block Diagram
* Mini Dopplex Only
Speaker