[PeterN]

I was wondering if anyone knows if these AC/DC transformer-less sets were actually used on 110v DC anywhere, and when.

I read that the model 40 (1929) was actually made for 110v DC only. I expect that consumers in the "eastern seaboard" states, that were using the Edison System (New York) during the early days of electrification (1890's), would be likely 110v DC users, but that would have been long before radio really caught on, when most power distribution systems had been "standardized" on 110/220 AC. The "All American Five" transformer-less sets didn't really make a prolific appearance until after WWII when everyone was using 110v AC.

I find it interesting that the "transformer-less" sets mention AC or DC operation in their operator/service manuals and go so far as to mention that when running on 110v DC, if no sound is heard, reverse the plug.

I have searched the Internet without success, looking for any history that tells when and where 110V DC was used in the home, after the radio era began. 

Thanks in advance.

[morzh]

http://www.nostalgiaair.org/PagesByModel...040180.pdf


Model 40 does not have a rectifier, so it would be a DC only model.
This however does not say anything about using AC/Dc sets on DC. Which is perfectly fine.

[jrblasde]

Good evening, folks. Power station engineer here!

The east coast had pockets of DC-only power well into the twentieth century. I’m wanting to say it ran into the 1950’s, but certainly was common through the 40s. In fact, there’s still DC power transmission in various parts of the country. It’s just not distributed for use as DC.

[PeterN]

Joseph,

Thank you for the confirmation. I knew that there must be more to the Transformer-less AC/DC radios than the radio design engineers realizing "hey, we saved the cost of the power transformer, and by the way, you could also use it on 110v DC if you had any". I didn't know that anyone had any (I was born in 1956).

I know some of the later farm radios were designed to run on 32v "farm power" (local generators/windmills) that was being used for lighting in the barns, before the "rural electrification" movement started distributing standard power.