May 1959 Electronics World
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
Even after computers became
commonplace in cubicles and laboratories, engineers and technicians kept design
nomographs around for cobbling together attenuators, filters, voltage dividers,
etc. Trade and hobbyist magazines like Electronics World used to print
them as full-page features on a regular basis, and I have posted many of them on
RF Cafe over the years. This particular "Symmetrical T & H Attenuator Nomograph"
appeared in a 1959 issue. Maybe the editor thought that "Symmetrical T, H, O,
and Pi Attenuator Nomograph" would be too long of a title and that's why the "O" and
"Pi" was omitted even though they are clearly included in the chart. As can
be seen by inspection of the circuit constructions, the T and Pi configurations
are "unbalanced" while the H and O configurations (bottom row) are "balanced." A
quick WWW search turns up plenty of attenuator design apps that not only solve
for the exact theoretical values of resistors but also will select the nearest
standard value resistors. Some will even then calculate the resulting
attenuation value based on those non-exact resistor values.
Symmetrical T & H (and O and Pi) Attenuator Nomograph
Posted July 1, 2019