# Technical Resistor Calculator

• Ohm's Law
• Series/Parallel
• Voltage Divider
• RTD's
• Wheatstone Bridge
• RL, RC Filters

## Ohm's Law

 Enter Any Two Numbers Press Calculate to find the others. Power (P) Watts Voltage (V) Volts Current (I) Amps Resistance (R) Ohms

Ohm's Law
V=IR
Joule's Law
P=VI
Ohm's Law describes the relationships
between Voltage, Current, and Resistance
through a resistor. It is the most
fundamental equation in electronics.
Joule's Law describes the amount of
power that is required to sustain a
certain current through a circuit.

Using these two equations, if we know any two values, we can determine the others.

## Series/Parallel

 Enter Values Leave One Blank RT R1 R2 R3 R4

 Find the equivalent resistance (RT) of resistors in series, parallel, or a combination
 Select Circuit Type Series Parallel Triple Series Triple Parallel Series - Parallel Series - Parallel - Parallel
If you get "No Solution"       Result was a Negative Resistance.

## Voltage Divider

RT - Total Ohms
Ohms

 Voltage Dividers Voltage Dividers are very useful for lowering voltages to use as inputs for control circuits. They are nice because the output voltages will track the input voltage very precisly. The output voltages are determined by theratios of the resistors chosen. Use this tab to find the best choice for your application. Fill in empty values, press Calculate.

Amps
 Volts Volts Volts Volts Volts
 Select Circuit 4 Resistors 3 Resistors 2 Resistors

## RTD's

 Temperature Coefficientof Resistance ( TCR ) Certain resistance material undergo a largechange in resistance due to temperature changes.These changes are controllable and repeatablemaking it highly suitable for measuringtemperatures. RTD's are a case of this. TCR is measured in parts per million per C(ppm/C), i.e. a 1 ohm resistor will change invalue by 0.0045 ohms for every 1C change intemperature for a 4500ppm/C wire. Use this tab to calculate either the resistancechange or temperature change based on differentstandard resistance material. Use the Temperature tab to convert Farenheit toCentigrade. Temperatures must be in C.
 Enter StartingConditions Enter One EndingCondition Starting Temp ( C ) Ending Temp ( C ) Starting Resistance (Ohms) Ending Resistance (Ohms)
 Select TCR( ppm/C ) +2600: 42% Ni Iron  +3850: Platinum  +3900: Copper  +4500: Balco  +5000: 99.5% Nickel  +6000: 99.9% Nickel
 Temperature Conversion Enter Farenheit or Centigrade - click Convert Farenheit ( F ) Centigrade ( C ) To

## Wheatstone Bridge

VVolts

R1Ohms
 R2 Ohms R3 Ohms R4 Ohms

V0Volts

VoutVolts

 Standard Circuit RTD Circuit

## RL, RC Filters

 Select Circuit Type Lowpass RL Circuit Lowpass RC Circuit Highpass RL Circuit Highpass RC Circuit
 Enter Any Two Numbers Press Calculate to find the others. Frequency(F0) Hz Inductance(L) mH Resistance(R) Ohms