Calculators for Radio Repair and More

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This webpage was created with the intention of coalescing several useful formulas from various sources that I commonly use in radio repair or building projects. These calculators do not have much description in their usage besides the quick reference images that are placed at the right if present. The formulas behind each calculator can be easily seen in the Javascript source in the head of the HTML file on this webpage. Hopefully one or more of these calculators below are useful for your purposes.

Generic Voltage Divider

Input VoltageVolts
Resistor 1Ohms
Resistor 2Ohms

Resistor Voltage Drop for Load

DC Supply VoltageVolts
Load VoltageVolts
Load CurrentAmperes

Inductive or Capacitive Reactance

ValueHenries or Farads
Resonant ComponentFarads or Henries

LC Resonant Frequency


Voltage Drop for Series Tube Filaments

AC Supply VoltageVolts
AC Supply FrequencyHertz
Cumulative Filament VoltageVolts
Filament CurrentAmperes
Surge Limiter Voltage DropVolts
Dropper CapacitoruF
Surge Limiter ResistorOhms
Resistor WattageWatts

Dropper Resistor with diodeOhms
Resistor WattageWatts

Dropper ResistorOhms
Resistor WattageWatts

Villard Voltage Doubler Output

AC Supply VoltageVolts
AC Supply FrequencyHertz
Number of Cascades
Output Load CurrentAmperes
Capacitor *Farads
* Assumes capacitors in doubler cascades are all the same value.

Power Supply Output Voltages

AC Supply VoltageVolts
AC Supply FrequencyHertz
Output Load CurrentAmperes
Filter CapacitorFarads
Rectification Method
DC Average Output VoltageVolts
AC Ripple VoltageVolts

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