Electronics and Instrumentation Calculators

Voltage divider, LED resistor, RC filter, op-amp, 555 timer, 4-20 mA scaling and RTD calculators with formulas and worked examples.

Small-signal and instrumentation work needs quick, reliable arithmetic: the series resistor for an LED, the output of a voltage divider, the cutoff of an RC filter, the gain of an op-amp stage, the frequency of a 555 timer. The instrumentation tools scale a 4-20 mA loop to the process value and convert Pt100 or Pt1000 resistance to temperature.

Where to start

1. Voltage Divider: Output voltage and divider current from two series resistors.
2. LED Series Resistor: Series resistor value and power for an LED.
3. RC Filter Cutoff: Cutoff frequency of a first-order RC filter, with gain and phase.
4. 4-20 mA Signal Scaling: Convert a 4-20 mA loop current to the process value.

All 12 calculators in this category

Electronics

• Voltage Divider: Output voltage and divider current from two series resistors.
• LED Series Resistor: Series resistor value and power for an LED from a fixed supply. Open in Elecmetric
• RC Time Constant and Cutoff: Time constant and cutoff frequency of a first-order RC circuit. Open in Elecmetric
• Decibel Converter: Convert voltage and power ratios to decibels and back. Open in Elecmetric
• Op-Amp Gain: Gain and output voltage of an inverting or non-inverting op-amp stage. Open in Elecmetric
• RC Filter Cutoff: Cutoff frequency of a first-order RC filter, with the gain and phase at a chosen frequency. Open in Elecmetric

Instrumentation

• 4-20 mA Signal Scaling: Convert a 4-20 mA loop current to the process value. Open in Elecmetric
• RTD Resistance to Temperature: Temperature from the measured resistance of a platinum RTD such as Pt100 or Pt1000. Open in Elecmetric

Semiconductor Components

• Zener Shunt Regulator: Series resistor and power ratings for a zener diode regulator. Open in Elecmetric
• Transistor Base Resistor: Base resistor to drive a bipolar transistor hard into saturation as a switch. Open in Elecmetric
• 555 Timer Astable: Frequency, period and duty cycle of a 555 timer free-running oscillator. Open in Elecmetric
• Heatsink Thermal Resistance: Highest heatsink thermal resistance that keeps a device junction within its limit. Open in Elecmetric

What these calculators do not cover

Cross-check: all 12 calculators listed here are compared with 98 reference calculations written separately from the engine. This confirms the arithmetic and selection rules. It does not confirm that a standard table or convention matches your standard or manufacturer data.

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