Deutsche Version

● 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
(audio), 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.

asymmetric
symmetric

Historical reasons
show impedance values especially of 50 ohms, 200 ohms, or 600 ohms.

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.

Vin

volts

Z1

ohms

Z2

ohms

Vunloaded

volts

ZL

ohms

output
voltage

Vout

volts

Vunloaded means Vout without ZL. If wanted, Zsource of the
generator can be added to Z1.

Voltage
damping D = 20 ×
log10 (

Vout

)

dB

------

---------------

Vin

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

Voltage damping:

Output voltage:

Parallel resistance:

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:

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.

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.
If wanted,
Zsource of the generator can be added to Z1.

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

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

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

A panpot is made of two voltage
dividers:

Calculator:
Unloaded or open circuit voltage divider
(potentiometer)

In
sound engineering there is no Impedance matching or Power matching.
In
audio we use only (high) Impedance
bridging or
Voltage
bridging.

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something from this website to enhance your knowledge.
Please, also
give some feedback to the author to improve the
performance.

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