#16
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My childhood Arvin 446p used 2 zinc carbon cells in parallel to power filaments of a similar tube complement (3S4, 1U5, 1T4, 1R5) which seemed to work fine. Of course today I use Alkaline cells!
jr |
#17
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Outdated info deleted (paralleling zinc-carbon cells).
Last edited by old_coot88; 01-24-2017 at 07:47 PM. Reason: Outdated info. |
#18
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The so-called 3 way portables, AC/DC battery sets had the tube filaments in series in order to run them off the B+ supply using a large voltage dropping resistor, when operating off the power line. The simpler designs used a 7.5 or 9 volt battery for the "A" supply, depending on the tube count. The more complicated designs used either 1.5 or 3 volt "A" supply. The power change over switching was more involved because the tube filaments had to be switched to series-parallel or parallel, plus having to take the cathode biasing into consideration. |
#19
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#20
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Way back, when I first started working on radios, the battery-only radios seemed to be around, free or very inexpensive. The electronic magazines had circuits for the "B" battery eliminator, but nothing for the "A" supply. Flashlite cells were inexpensive, so I built the "B" supplies and used the radio that way.
I always wondered why someone would buy a radio that cost that much to operate, when for a few bucks more, you could buy a radio that you could use year round. "B" batteries were always expensive. |
Audiokarma |
#21
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Design wise, elimination of the built in power supply, complex switching for the filament circuit, and space for cord storage allowed for a more compact design, which might have been a selling point. The "B" batteries lasted pretty well compared to the much cheaper flashlight cells used for the "A" supply. IIRC, the 67 1/2 Volt battery was nearly 3 bucks in the 50s... nice birthday or xmas gift for a little kid. jr |
#22
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__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#23
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That has to be a safety feature from shortly before the government mandated magnetic door handles.
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#24
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I've heard stories* of folks getting locked inside of old latching style fridges and suffocating or the like.... *From my mom in the 90's when in our old town we would see such fridges at the curb occasionally, and I was a dopey curious kid.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#25
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I don't know for sure, but I think the reality of it was that the average mom just unreasonably worried that their child would be stupid enough AND go through the effort of removing all the food AND shelves so they could play hide and seek, hiding in the fridge - and Admiral thought it would make a nice selling feature to the concerned parent. Last edited by MadMan; 01-24-2017 at 10:58 PM. |
Audiokarma |
#26
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Back in the 1950's high capacitance, low voltage Electrolytics weren't that common, so it would be too costly to build an "A" supply with little or no hum. |
#27
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I'm leaving it the way it is! Like the letters GE mean: Good Enough! |
#28
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Thanks for mailing that thingy btw. (Vinyl still prefers her headphones.) Last edited by MadMan; 01-28-2017 at 03:16 AM. |
#29
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