[Buzz]

Hello all...
I have always wondered why the labels on some my radios say 110 V AC or DC.
Does that mean I can run it on DC?.... What would happen if instead of plugging it in to AC, I attached 110V DC to the plug? Would it work?
Just wondering...
Buzz

[morzh]

If it says DC, it probably is "hot chassis" set that has no power transformer and has rectifier directly from Mains.

This means that it can use both AC and DC.

This should never be attempted with AC transformer sets - 110VDC will burn the transformer.

[Buzz]

Hi:
These radios are AA'5. no transformers.
The reason i asked is i just assembled a battery eliminator from AES (antique electronic supply) I wanted to try it.......
Can you explain what happens when dc goes through a rectifier etc on an AC system,, It seems puzzling to me, of course im always puzzled..
Buzz

[BrendaAnnD]

Buzz,

A battery eliminator will not power an AA5, it does not have anywhere near enough current capability.

That being said, if you put 9 or 10 12 volt batteries in series, you've got it made.

Note that the radio will only work on DC with the plug in one way, but not the other. The reason for this is the action of the rectifier tube, which will only conduct in one direction when supplied with a DC source.

Also, the radio's performance on DC will be somewhat diminished, because you have the double whammy of the rectifier's forward voltage drop, combined with the fact that you do not gain the additional B+ voltage that you would using AC (110V DC minus the forward voltage drop is around 100V DC for B+, vs. 110V AC minus the forward voltage drop, but then mulitiplied by 1.414 (peak AC).

[Buzz]

thanks guys.. i tried it before you answerd brenda, and it powered up about 5 sec and...well something got hot.. was worth it anyway..
thanks guys,
buzz

[chris25260880]

This dumb question.....(not dumb at all) brought to mind a recent trip to Boston. While walking on Clarendon St the building which housed the old Hard Rock Café and earlier a wonderful nightclub called Jason's has a very interesting feature on the side of the building. There is a Boston Edison panel which still says this building is served
by Edison DC service only. When the building was rewired to AC I do not know.
Even more interesting is Con Edison service in NYC where parts of Manhattan still had only DC service until the late 50's. I have advertising by Con Edison listing brands of TV's radios and appliances for DC use available at their stores with listings of other dealers where this stuff could be purchased. Tesla must have had a laugh as Thomas Edison's DC breathed its last breath although he may have been too busy tending to sick pigeons by that time in his life.

[Electrothaumaturgist]

Tesla died in '43 a broken and defeated (by the powers that be) man, and never got to see the end of DC service, unfortunately.

[Arran]

There is a luxury hotel in Victoria B.C that had it's own power plant up at least until the 60s, it produced 110 VDC so the rooms never had any TV sets up until that time. It was owned by Canadian Pacific who also owned a railroad and it's own steamship line, the steamship terminal was just across the street.
Someone on the alternative forum mentioned working in a building that had DC outlets on the premises. I don't know if they still do but he mentioned testing out an AC/DC set just for laughs and it behaved pretty much as Brenda Ann summarized. There were some Philco models that were DC mains only, not battery, they were series string, with a large ballast, and did not have a rectifier tube.
I think that the fact an AA5 could run off of DC mains was more of a marketing ploy then a practical feature, even in the 1930s, as the market was fairly small. The real innovation was that they could build a cheap set mass market set with no power transformer.
Regards
Arran