A WIZARD'S ELECTRONICS COMPANION

ATTENUATORS

T-Attenuator

If you just want to attenuate the voltage then a two-resistor voltage divider is all you need, but if both the source and load need to "see" a certain impedence and the source is capable of having plenty of drive voltage and current for the load then a T-network may serve. Note that R3 is common to both, so the impedence of R3 in parallel with the opposing side is the minimum either side can see. As R2 approaches zero, it drops into the simpler two-resistor voltage divider.

Pi-Attenuator

If the impedence one side must see is small compared to the other, the pi-network is used.