# Attenuator calculation Assistance

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#### hantu lipas

##### New Member
A symmetrical pi attenuator its central arm of 800Ω and each two limbs of 400Ω
If this pi attenuator is connector in between a voltage source of 240v having an internal resistance Rs and a load resistance RL = Rs = Ro

1. find the input voltage?
so the input voltage is (240/2)= 120v ?

2. the output voltage
not sure

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#### MrAl

##### Well-Known Member
Hello,

Assuming the center resistor is 800 and all the other resistors (4 of them) are 400 ohms, and the generator voltage is 240 volts, then the input voltage is 100 volts and the output voltage is 20 volts.
The formulas are:
Vin=Vgen*0.25*(R1+2*R2)/(R1+R2)
Vout=Vgen*0.25*R1/(R1+R2)
where
Vgen is the generator voltage, and
R2 is the value of the center resistor (800 ohms), and
R1 is the value of the four other resistors (400 ohms each).

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#### hantu lipas

##### New Member
sorry bout the first post.
anyway its unblance so its just only 3 resistors,
1 on the middle and 2 at the limb

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