Dc Voltage Measurement; Ac Voltage Measurement; Current Measurement - Elenco Electronics M-1005K Assembly And Instruction Manual

DC VOLTAGE MEASUREMENT

Figure 7-4 shows a simplified diagram of the DC voltage
measurement function. The input voltage divider resistors
add up to 1 megaohm. Each step down divides the voltage
by a factor of ten. The divider output must be within the
range -0.199 to +0.199 volts or the overload indicator will
function. The overload indication consists of a 1 in the most
significant digit and blanks in the remaining digits.

AC VOLTAGE MEASUREMENT

Figure 7-5 shows a simplified diagram of the AC voltage
measurement function. The AC voltage is first rectified and
passed through a low pass filter to smooth out the
waveform. A scaler reduces the voltage to the DC value
required to give the correct RMS reading.

CURRENT MEASUREMENT

Figure 7-6 shows a simplified diagram of the current
measurement function. Internal shunt resistors convert the
current to between -0.199 to +0.199 volts which is then
processed in the 7106 IC to light the appropriate LCD
segments. When current in the range of 10A is to be read,
it is fed to the 10A input and does not pass through the
selector switch.
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c
c
e
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Figure 7-4
Figure 7-5
Figure 7-6