Why 6.3 volts?

Nah, it's like $9.98, instead of $10. It looks like it's less.

Exactly. How many items in the store are $xx.00? It's called "marketing" and it works. People really do think $9.99 is significantly less than $10.00.

Different issue entirely. The pumps around here say the limits are $90 Amex, and $75 for everyone else. That limit is because they put a "reserve" of that much on your account and then settle the actual amount some time later (usually a few hours). If you're long-distance driving you can occasionally beat them to clear the reserve and the card may be rejected (trying to fill twice, I suppose). I ran into this problem on my last trip to the People's Republic of Vermont. Had to use another card.

Yeah, but I bought my first airplane with the profit I made from Fairchild stock. First time I worked with those little buggers (time code generator) I told myself that this company was really going to go big. Still have a few of them around as museum pieces.

Jim

Think about it. When the first tubes with 6 volt filaments were designed, most automobiles had 6 volt electrical systems. If you wanted to use the same tubes for car radios as home radios, you used the same filament voltage.

In the mid-50s automobiles switched to 12 volt systems and RCA/Sylvania/GE, and the rest went to 12 volt filaments.

The all-American 5 used a 50C5 audio power, 35W4 rectifier, 12BE6 RF-Converter, 12BA6 IF, 12AT6 detector-audio preamp. Add up the filament voltages for an interesting look at a transformerless line voltage receiver.

Thanks,

Jim

So what. None of them had tubes and car radios were not incorporated yet.

It appear that you like to guess at things. You're not very goo at it.

Autos went to 12 Volts before the 50s, and tubes are STILL 6.3 volt filament devices. And any change they made was not because of the auto industry.

They are all 6.3 volt filaments.

And prudence probably dictated that the voltages be different, to prevent wiseacres from trying to use the same winding for the rectifier and signal tube heaters. :)

Cheers

Phil Hobbs

Spot on IMHO.

The round 8-lead black glob-top things?

John

Yeppers. As I recall without digging out the data sheets, an AND gate, a NOR gate, and a JK flipper.

Jim

I don't know whe the hell you are, but you'd be well advised to take my class on the history of electronics. Car radios were introduced in the 1930s.

I don't "goo" at anything. Get a spell checker.

I could be wrong. I've been wrong before. But to the best of my recollection the '53 Ford was the first 12 volt electrical system.

I refuse to have a battle of wits with an unarmed person. See ya later, Dumbo.

Jim

"RST Engineering"

... Phil

Yeah. There must have been a whole 300 of them installed throughout the entire depression decade.

Those were so awful that even DTL was an improvement.

John

Sounds like another incarnation of AlwaysWrong.

He is. Really. Always Wrong.

John

Police radios. Remember "Police Radio Car"?

John

Prices in the US very often end in "9". That avoids an increment of sales tax.

John

How do you figure that?

Sales tax in the NY state area where I often shop is 8.25%, so the nine doesn't generally help.

I've seen a trend in restaurants in recent years to mark things in even dollars without the $ sign. Eg. 'Insalata Caprese 10'.

Said AlwaysWrong in another of his endless nyms!

Just to be correct, none of these had "filaments", they were actually "heaters" which did not emit electrons, but heated the cathode sleeve around them. This was the element that produced the electron stream that made the tubes work.

Almost the only tubes still using an emitting filament are the rectifiers, and they are almost extinct due to solid state replacements.

Emitting filaments are not completely extinct. There are millions of magnetrons in microwave ovens that still use them. This allows for power control by cycling the total power to the tube.

Yup. As I recall, the first digits always* indicated the filament voltage.

• I think there were some exceptions, like tubes with the single digit 1 before the letter. The 1 meant ~1.5 volts, not 1 volt, if my very fuzzy memory is correct.

Ed