electrical equations
From Noah.org
P = E^2 / R
Contents
Voltage Divider
Voltage Divider No Load
The voltages are proportional to the resistances.
Vout = Vin * (R2 / (R1 + R2)) Vin = Vout * ((R1+R2)/R2)
Vout+ O Vout- O | | | | R1 | R2 | +--/\/\/--+--/\/\/--+ | | | | Vin+ Vin-
Voltage Divider Under Load
R2 || Rload = (R2 * Rload) / (R2 + Rload) Vout = V1 * ( R2 ||Rload) / (R1 + R2 || Rload)
Rload +--/\/\/--+ | | | | Vout+ O Vout- O | | | | R1 | R2 | +--/\/\/--+--/\/\/--+ | | | | Vin+ Vin-
Vout = Vin (
Picking a value for R1 and R2
Assume you have a restive sensor to test. Out of circuit you would test the sensor to determine its minimum resistance and maximum resistance. Then pick
R2 = sqrt (Rmin * Rmax)