• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Update On the Trace Eliott ELF That I Blew Up.

#441
BassmanPaul said:
Now that you mention it so do I! Drat!!
Click to expand...
I have a boom box from the eighties that will operate on AC or DC. Of course the DC is via internal D cells.

Before my time, but not much, weren't there radios that used large external batteries?
Some needed different batteries depending on what part of the radio they were powering, like a batt for filaments and another batt for the high voltage supply? Isn't that where the term B+ comes from? The B battery was used to supply high voltage for the tubes?

We need us an electronics archeologist... :woot:
 
#442
alaskaleftybass said:
:laugh:

Anyone have a theory why we even have different voltages from the US compared to Europe?
Click to expand...
I'll bet there are as many theories as there are people to provide an answer. My guess is that there was likely a set of trade-offs that may have included accepting higher insulation requirements and protocols for allowing the use of smaller copper in the wiring that led Europe to make its choice for higher voltage. As for the US, I think Edison having sort of set things up for us to be a 110-110 Volt (albeit DC) country by his initial design choices and the magic number sort of stuck for convenience.

As for 50 or 60 Hz, my guess is that there are too many variables to even begin to make a compelling case, but that at least for the US Tesla's initial calculations zeroed in on 60 Hz as a good optimal compromise between competing options. Even in the US we have varying standards in different industries. For instance aircraft often use 400 Hz AC to allow for downsizing of components (equal performance with less volume and mass). However, that only works well because the wiring/electrical system is very "local" - transmitting high frequency AC over long distances is not efficient/economical.
 
  • Like
Reactions: alaskaleftybass, BadExample, agedhorse and 1 other person
#443
Al Kraft said:
I'll bet there are as many theories as there are people to provide an answer. My guess is that there was likely a set of trade-offs that may have included accepting higher insulation requirements and protocols for allowing the use of smaller copper in the wiring that led Europe to make its choice for higher voltage. As for the US, I think Edison having sort of set things up for us to be a 110-110 Volt (albeit DC) country by his initial design choices and the magic number sort of stuck for convenience.

As for 50 or 60 Hz, my guess is that there are too many variables to even begin to make a compelling case, but that at least for the US Tesla's initial calculations zeroed in on 60 Hz as a good optimal compromise between competing options. Even in the US we have varying standards in different industries. For instance aircraft often use 400 Hz AC to allow for downsizing of components (equal performance with less volume and mass). However, that only works well because the wiring/electrical system is very "local" - transmitting high frequency AC over long distances is not efficient/economical.
Click to expand...
Yeah 400 cps :) mains means a great reduction of size and weight for filter caps and inductors in the power supplies. I suppose PS transformers as well? And in the tube days, there were a lot of inductors used in power supply filters.

Imagine having a ground loop with equipment running on 400 Hz mains? :jawdrop:
 
  • Like
Reactions: Al Kraft
#444
Old Garage-Bander said:
Before my time, but not much, weren't there radios that used large external batteries?
Some needed different batteries depending on what part of the radio they were powering, like a batt for filaments and another batt for the high voltage supply? Isn't that where the term B+ comes from? The B battery was used to supply high voltage for the tubes?

We need us an electronics archeologist... :woot:
Click to expand...
Yes, I remember my dad saying about a radio they had that used a 90v HT dry battery and lead acid "accumulator" for the tube filaments. They would go to great lengths to get the last bit of energy out of the HT battery by warming it up in front of the fire or putting it in a (not too hot) oven for a while.

The lead acid batteries were re-charged at a local shop.

I guy I still keep in contact with may remember more than I do, I'll post back if I find out any other gems from the past.
 
#446
Old Garage-Bander said:
Yeah 400 cps :) mains means a great reduction of size and weight for filter caps and inductors in the power supplies. I suppose PS transformers as well? And in the tube days, there were a lot of inductors used in power supply filters.

Imagine having a ground loop with equipment running on 400 Hz mains? :jawdrop:
Click to expand...

25 Hz would have been good, as you'd be able to filter out the main hum component out of music...
 
#451
-Asdfgh- said:
25 Hz would have been good, as you'd be able to filter out the main hum component out of music...
Click to expand...
Although house lighting would have probably had a noticeable flicker that would have been annoying to most and a serious issue for folks who experience epileptic episodes triggered by strobing lights.
 
  • Like
Reactions: BassmanPaul
#453
BassmanPaul said:
How? If you rectify and smooth it it is 25Hz. Full wave rectification makes that 50Hz. Both are more difficult than the 50/60Hz that we use today.
Click to expand...
Maybe Asdfgh meant that because it was so low in frequency it could be effectively filtered with no/very minimal effect on the true audible frequency spectrum where we enjoy our music??
 
#454
Al Kraft said:
Although house lighting would have probably had a noticeable flicker that would have been annoying to most and a serious issue for folks who experience epileptic episodes triggered by strobing lights.
Click to expand...
Probably not an issue with incandescent bulbs.

It seems there was a study, or studies, that determine the lowest frame rate of film before someone could detect flicker. This may have carried over to TV frame/field rates as well, Though in TV I think those are more tied to mains line frequency. In the US NTSC TV frame rates were 30 fps (actually just a hair less) approximately half the power line frequency of 60 Hz. PAL TV used in Europe and nearby areas had a frame rate of 25 Hz, half of their AC mains frequency.
It's been a while since I played with NTSC video, but as I recall, the US black and white TV standard was exactly 30 frames / 60 fields per second so it would best sync up with the power line frequency (as stable as that may have been). When they invented color TV the frame rate was changed slightly.
 
#456
ForthrightGentleFruitbat-size_restricted.gif
 

Latest posts

Top Bottom
Back