Javascript Tools

Simple JavaScript tools with minimal input error checking



A.   Calculate 2 Resistor Voltage Divider Bias

Enter Voltage:    Enter R1:   Enter R2:      Bias voltage  =  



B.   Calculate Inductive Reactance

Enter Inductance in uH:    Enter Freq in MHz:      XL (ohms) =  



C.  Calculate # of Turns To Obtain a Desired Inductance on a Ferrite Toroid

Enter Inductance in millihenries:    Select Core:        Turns  =  
The AL for this ferrite core is   =  



D.   Calculate Cut off Frequency for an RC Pi Low-Pass Filter

Enter resistor value in ohms:    Select capacitor values in uF:         
3 dB down frequency (Hertz)  =  



E.   Calculate Power in dBm and mW from Peak-to-Peak Voltage

Enter measured peak-to-peak voltage into a 50 ohm load:            dBm,     mW

Application Note: This web site follows the EMRFD standard for dBm power measurement. dBm = the power delivered into a 50 Ohm resistive load which is temporarily substituted at that point in the signal chain



F.  Calculate   Lm and Cm For a Crystal using the G3UUR Method

Enter frequency in MHz written on crystal (series resonant frequency):

Enter measured frequency in MHz with switch open:  Enter measured frequency in MHz with switch thrown:

Enter crystal capacitance in pF:  Enter open switch circuit capacitance in pF

    Cm   =    femto Farads ,  Lm  =   Henries



G.   Calculate Decibel Power Gain or Loss from 2  Peak-Peak Voltages

Enter voltage 1:    Enter voltage 2      dB gain or loss =  



H.   Calculate Decibel Power Gain or Loss from Input and Output Power 

Enter input power in watts:    Enter output power in watts      dB gain or loss =  



I.   Calculate dBm and mW from RMS Voltage (50 ohms)

Enter RMS voltage            dBm       mW



J.  Calculate Return Loss and VSWR (50 Ohms Detector) 

Enter the detector signal in pk-pk volts when the unknown port is terminated in an open circuit:    
Enter the detector signal in pk-pk volts with the ? impedance connected:
 

   Return loss =   dB,   VSWR=1:     Measurements per Figure 7.41 EMRFD.



K.  Calculate Power from the DC Output of an AD8307 Meter

1. Linear calibration steps:
Enter measured DVM voltage at -10 dBm:    Enter measured DVM voltage at -20 dBm:   

2. Calculate power in dBm from DVM voltage:
Enter measured DVM voltage:           Power  =  



L.   L-C-C Tee Network

Enter frequency in MHz: 

Enter R1 in Ω:     Enter R2 in Ω:      R1 must be < R2, but the network is bi-directional

Enter Q:       Perhaps start with 2-5

     C1 =   pF,  C2 =   pF,  L =   uH



M.  Parallel Resistor Values   (2-4 resistors)   [ also may use for series caps etc. ]

Enter R1:    Enter R2     Enter R3:    Enter R4:   

        R =   ohms



N.  LCR -- a Reactance Calculator    In beta -- do not use !


Mode:    Inductance:    Enter frequency in MHz