101 Electronic Projects magazine
This 1974 edition of 101 Electronic Projects (for under $15) is one of my favorites.
Not sure why, none of the projects are shown built or photographed, just schematics and a few comments. They made a few additions/deletions with every annual issue. But it was a fun source of inexpensive (cheap) project ideas. Of course the superb web site World Radio History has this issue:
https://worldradiohistory.com/Archive-Hobbyist-Specials/101-Electronics%20Projects-1974.pdf
along with a nearly complete collection of these compilation magazines like the Electronic Experimenters Guide and others (almost every electronics magazine published one):
https://worldradiohistory.com/Hobbyist_Special_Editions.htm
Archive.org also has this 1974 issue: https://archive.org/details/101ElectronicsProjects1974/mode/2up
While looking through this 1974 issue this scrambler project on page 29 caught my eye:
It uses a diode bridge configuration (same as in a power supply) which is different from what is normally presented in a diode ring modulator where the diodes are connected anode to cathode in a ring. Searching I found this figure from the April 1953 QST page 42, an article by Byron Goodman (so I'm pretty sure it's not an April fool).
Two modulators are shown, the one on top is a diode bridge, the bottom a diode ring.
Also found this blurb in an RCA Linear IC book about the CA3019 diode array which includes a diode bridge:
Again a very similar modulator to that shown in 101 Electronic Projects.
One potential advantage of a diode bridge over a diode ring is that they are more available pre-packaged for the ham.
The diode bridge modulator looks interesting to me if for no other reason that trifilar windings are not used on the transformers. Telling two (bifilar) wires apart wound on a toroid isn't too bad but three wires is more of a hassle since it's easy to get two colors of magnet wire but 3 colors is a little harder. There is probably some performance reason why the diode ring is preferred to the diode bridge. Although it might just be that three transformers are used with the bridge where two transformers are usually used with the ring ?
More investigation is called for !
Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm