H. P. Friedrichs (AC7ZL) Homepage
This page contains links to articles, essays, hard-to-find information, and excerpts from old volumes in my personal library. Some documents are in html, others in pdf format. Some of these items were sent to me by fellow experimenters, scanned from old journals, or other undefined sources.
This site was never intended as a soap box on which to debate politics, religion or anything else of that nature. More often than not, it simply puts people off. On the other hand, the events of this week are the kind that stay with you your whole life. Like Pearl Harbor, or the Kennedy assassination, none of us will ever forget where we were and what we were doing when the United States suffered this attack.
The day before the attack, I happened to take a photograph that, in the context of subsequent events, has taken on new meaning. Click on the link above to read about it.The Crystal As A Generator And Amplifier (PDF)
When you think of "crystal" radio, you usually think of passive receivers, right? How about crystals that have the capacity to amplify and even to transmit! This is an excerpt from a 1924 issue of Wireless World. This article came to me as an attachment from a fellow experimenter.Transistors In 1923? (PDF)
This is an excerpt from the January, 1959 issue of CQ. It recalls experiments with detector crystals probed with not one but two cat whiskers, and asks if this might not have been a precursor to the invention of the transistor. This article came to me as an attachment from a fellow experimenterThe Manufacture Of Vacuum Detectors (PDF)
This is a really bad scan of article of undetermined origin, possibly prior to 1920. Interesting, none the less. (Incomplete)Some Aspects Of Radio Valve Manufacture (PDF)
Here is an excerpt from a 1942 issue of Electronic Engineering Magazine. Submitted to me as an attachment from a fellow experimenter.Anode Materials For High Vacuum Tubes (PDF)
Another excerpt from Electronic Engineering Magazine, date unknown. Submitted to me as an attachment from a fellow experimenter. (Incomplete)Materials For Vacuum Tube Manufacture (PDF)
An excerpt from a 1940 issue of Industrial and Engineering Chemistry. Submitted to me as an attachment from a fellow experimenter. (Incomplete)
This is an excerpt of the 1924 volume entitled, How To Build Your Radio Receiver by the famous Banning and Cockaday. The design, already classic in its own time, is a recreation of the famous "Bureau of Standards" crystal set. Check it out.
Published in 1913, Wireless Telegraph Construction for Amateurs is a classic Alfred Morgan tome. The links above will take you to excerpts scanned from my copy of this work, arranged according to subject matter. Look to see what radio experimenters were building nearly a century ago.