Calculations voltage divider - loaded and open-circuit damping pad volts dB attenuator potentiometer damping circuit decibel impedance bridging matching - sengpielaudio
 
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● Calculations:  voltage divider or potentiometer ●
Loaded and open circuit (unloaded) − damping pad
Voltage drop at the voltage divider
 
Using impedance matching or power matching you make the output impedance of a source equal
to the input impedance of the load to which it is ultimately connected. T- and H-pads are used in radio
frequency (RF) circuits to attenuate a signal (damping). It is applied where maximum energy (power) is
transferred between a source and a load. Then Zsource = Zload.
 
But in sound recording, public address, and HiFi only impedance bridging is used with:
 
Zsource << Zload or ZS << ZL or Zout << Zin
 
The output impedance of the source is always much smaller than the input impedance of the load.
In this case never try to calculate and use T- and H-pads circuits - better use voltage dividers instead.

Voltage divider - sengpielaudio
asymmetric                   symmetric

Voltage Divider Calculator No. 1
 
Entering three or four values calculate the others. The value of Zload can be entered additionally,
otherwise it uses automatically a 1 megohm load - unloaded open circuit.
Use the left mouse button - click at a free space.

 
voltage divider - sengpielaudio Vin =   volts
Z1 =   ohms
Z2 =   ohms
Vunloaded =   volts
ZL =   ohms
 output voltage   Vout =   volts

Vunloaded means Vout without ZL

 
 Voltage damping D = 20 × log10 ( Vout  ) dB 
------ ---------------
Vin 

A negative solution means damping (loss) - positive solution means amplification (gain).

Voltage damping:  weiter

Output voltage:  weiter

Parallel resistance:  weiter

See also:  Calculation of damping
Impedance bridging or Voltage bridging Zout < Zin

Unloaded voltage divider
 
Rule of thumb: The voltages are proportional to the resistances.

Formulas for the unloaded voltage divider:

formula 01
formula 02
formula 03
formula 04

Calculator: Unloaded or open circuit voltage divider (potentiometer)

Voltage Divider Calculator No. 2

This calculator, given any three or four of the five possible values, will give the
results for the remaining one. The ZL value is optional, if not supplied, the
calculator uses 1 Megohm. Usefull if you need to enter Vout.
Fill in any three or four fields in the form below, then click the "calculate" button.
The remaining field will be calculated, and the results displayed. If you make a
new calculation, use always the "reset" button to clear all the boxes. Z = R.
 
voltage divider - sengpielaudio Vin   volts
Vout   volts
Z1   ohms
Z2   ohms
ZL   ohms
                                
To compute Input Voltage enter Z1, Output Voltage, and Z2 and then click the calculate button.
To compute Z1 enter Input Voltage, Output Voltage, and Z2 and then click the calculate button.
To compute Z2 enter Input Voltage, Output Voltage, and Z1 and then click the calculate button.
To compute Output Voltage enter Input Voltage, Z1 and Z2 and then click the calculate button.

Voltage division ratioα = Ratio (Output Voltage to Input Voltage) = Vout / Vin
Z2 = (α × Z1) / ( 1 − α)
dB (level) = 20 × log α
Vout = Vin × [Z2 / (Z1 + Z2)]

Interconnection of two audio units - voltage bridging Zout < Zin
Calculation of the damping of impedance bridging or
impedance matching an interface connecting Zout and Zin

Voltage divider (potentiometer) with different control characteristics
Figure: © Detlef Mietke − http://www.elektroniktutor.de/analog/u_teiler.html

Potentiometer - sengpielaudio

Interconnection of two audio units equals a circuit of a voltage divider − Z2 << Z1.

interface sengpielaudio

Attention: The numbering of the impedances is inversely to a voltage divider.

voltage divider

A panpot is made of two voltage dividers:

Panpot

Calculator: Unloaded or open circuit voltage divider (potentiometer)

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