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8. Block diagram
The driver block diagramme (pulse power supply) D-31M is presented in
fig.10.
The pulse power supply of light-emitting diodes functionally consists of
generator G, single-shot multivibrator M, multiplexer MX1, voltage-to-current
converterv U/I, the pulse power supply converter DC/DCLED.
The generator G forms the pulse sequence with variable repetition rate. The
repetition rate can be changed with the help of the button "Frequency". It's
indicated by light-emitting diodes “2 kHz”, “4 kHz”, “8 kHz”, “16kHz”. The
waiting multivibrator M and the multiplexer MX1 receive the voltage impulses in
the form of a meander from generator G .
The single-shot multivibrator M generates voltage impulses with the
adjustable fixed duration synchronously with rise-up portion of input voltage
impulses. Switching of duration of impulses is carried out by means of switch SW1
in the range from 0,6 to 20 µ
с
.
The multiplexer MX1 by means of the button “Operating mode” switch the
clock pulses on the input of voltage-to-current converter U/I. In addition clock
pulses come to the jack “Synchro” for synchronisation with the external
photoreception amplifier.
The IR-light-emitting diode LED recive a pulse current from U/I converter.
Start-up of circuit U/I is carried out by means of the button “Curent ON/OFF”. The
green light-emitting diode “Work” lights up in that case . If the circuit of the LED
is broken the light-emitting diode “Break” lights up. Adjustment of the amplitude
of the LED pulse current is implemented by means of a multiposition switch SW2.
The DC / DC circuit is a pulse voltage converter from + 12 V in + 5 V, -5 V
for power supply of all the elements of the D-31M. The input voltage of DC / DC
converter supplies from “+12 VDC” jack.
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