SA2005F
sames
VOLTAGE DIVIDER
The voltage divider is calculated for a voltage drop of 14V.
Equations for the voltage divider in figure 5 are:
RA = R16 + R19 + R22
RB = R8 || (R13+P1)
Combining the two equations gives:
( RA + RB ) / 230V = RB / 14V
A 5k trimpot is used in each of voltage channel for meter
calibration. The center position of the pot is used in the
calculations. P1 = 2.5k and values for resistors R13 = 22k and
R8 =1M is chosen.
Substituting the values result in:
RB = 23.9k
RA = RB x (230V / 14V - 1)
RA = 368.9k.
Resistor values of R16, R19 and R22 is chosen to be 120k,
120k and 130k.
The three voltage channels are identical so R14= R15= R16 =
R17 = R18 = R19 and R20 = R21= R22.
6/10
SAMES [ SAMES ]
