LX2
plus / advanced and LX4 plus / advanced
B2270901
Content is subject to change without notice!
13
3.4.3
Microcontroller
All the controlling tasks are done by the 8 bit controller circuit IS1. The clock is generat-
edby the internal oscillator. External components belonging to the oscillator are the ca-
pacitors C4 , C5 and crystal Q1. Transistor T3 with additional components R8, R9, R16
and C6 form the necessary reset circuit.
The UART, implemented in the controller, allows communication with the pager. The sig-
nals RxD and TxD are coupled to one wire using diode D10. Resistor R15 serves as a
„pull-up“ resistor connected to the communication wire which is used in both directions.
3.4.4
Temperature Supervision
The Charging Unit supervises the ambient temperature during the charging procedure and
varies the charge current accordingly, i.e. accelerated charge is permitted within a speci-
fied temperature range, only. The voltage of the resistive devider R31/ R32 is measured.
R31 is a temperature-dependent resistor.
3.4.5
External Alert Devices
After reception of
an alert, relay REL1 is activated by T6 and R13. Resistor R30 limits the
current and D2 serves as a free-wheeling diode. The time the relay stays active , i.e.the
time the working contacts REL1A are closed, can be programmed (pager programming).
Furthermore a square signal of appr. 1.2 kHz is output via transistor T4 (base resistor R2).
This transistor can be made up with external components, e.g. loudspeaker.
As an option, a switching circuit (R41, R42 and T12) can be placed which can drive a
suitable Buzzer SU1 for additional loud alert.
The alert can be erased by pressing button TA1 on the charger. The switching signal is
filtered by resistor R47 and capacitor C11.
