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3. Circuit Description
3-1. ANALOG TO DIGITAL CONVERSION
When all values to be measured are connected to R72,
they are applied to U10-10
and the LED driver signal of U10-12, 17, 18, 19, 20 23 and the BCD signal of
U10-13, 14, 15, 16 are output by integral constant of R69, R70, C32, C33 and the
value is displayed on LED with U13 BCD to 7-segment decoder.
3-2. SYSTEM REFERENCE
The reference of the value(1.0000V)to be measured is applied to U10-2 at VR15.
3-3. System Frequency
The 100kHz square wave generated at Y1 (Crystal) is applied to U10-22.
3-4. Power Circuit
AC power source is used as input power, and AC voltage is applied to each
regulator IC passing 2 rectifier circuits at 2
nd
side of the power transformer.
3-4-1. +5V Circuit
As the voltage rectified through D15, D16, D17, D18 rectifier diode at the 2
nd
side of the power transformer is applied to regulator IC J13-1, +5V is output to
regulator J13-3 and applied through R32 to a circuit that needs +5V.
3-4-2. -5V Circuit
Output of +5V is converted to
–
5V by being applied to
ZDP1, C45-1,
and
–
5V is
applied to a circuit that needs.
3-4-3. +15V Circuit
Of the voltages rectified through D19, D20, D21, D22 rectifier diode at the 2
nd
side of the power transformer, cathode of D20 and D21 is applied to U15-1, and
at this time +15V is output to 3 and applied through D23 to the circuit that
needs +15V.
3-4-4. -15V Circuit
Of the voltages rectified through D19, D20, D21, D22 rectifier diode at the 2
nd
side of the power transformer, cathode of D19 and D20 is applied to U16-2, and
at this time +15V is output to 3 and applied through D24 to the circuit that
needs +15V.
3-4-5. Frequency Power (+5V)Circuit
J14T and J14 are used as power supply for frequency measuring circuit by
outputting power supply of +5V to 3 by applying output of +15V of D23 cathode to
U20-1.
3-5. 10-Time Amplifier Circuit
All signals can be applied in DC voltage to R72 that is input of A-D converter,
only through the 10-time amplifying circuit by using op-amp of U14.
