Silicon-Free Fixed Bias?

[g1]

Yes.
I saw it on the Mattrix.

[R.G.]

Well, I <WAS> born about 40 miles from Three Mile Island, on the same night it blew up... the hospital was under advisement for evacuations... So, I think I'll be okay! :P

You're too young to remember the fun then. There was a tee shirt a little while after that that said:
====================
I survived Three Mile Island
I think...
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Edit: I think it's entirely within the realm of possibility that there could be a way to have an EMP without the radioactive side effects...

Indeed it is. The EMP from a nuclear blast comes from the X ray and gamma ray produced by the reaction running into gasses that are thicker on one side than another. EMP from a blast in the lower atmosphere isn't too severe - at least the heat, radiation, and blast wave would be much worse than the EMP. The recipe for monster EMP was something like exploding a several megaton blast just in the upper atmosphere. This makes for an EMP that's - um, noticeable. As in melting-aluminum-foil noticeable. But the radiation and blast are not going to be a problem. This is all fairly dim in my memory. I'd have to go look up the actuals.

I'm a child of the era where we had nuclear-attack drills in elementary school. I was taught the Right Way to cower under my desk, away from windows and doors.

[The Dude]

...I'm a child of the era where we had nuclear-attack drills in elementary school. I was taught the Right Way to cower under my desk, away from windows and doors.

Oh god, I remember those drills! Even at that young age we wondered what the hell good a little wooden desk was gonna do if there was a nuclear attack. I guess it'd make it easier to find the dead kids. Just look under all the desks.

[J M Fahey]

It's basically for broken glass protection.
You have a quite a few miles wide ring around deadly blast and heat effects where people just hear a lod thunder ... but glass shards fly all over the place.
Besides, given the often light construction found all over USA: wood structure and drywall, lots of it will crack and crumble under relatively light blast pressure which would not affect brick and concrete.
I bet the idea was not saving life , if you are in the deadly zone you are dead, if you are not, not, but to avoid needlessly filling hospitals wityh thousands of children not in full peril of death but bleeding from dozens of skin cuts and their hysterical mothers.

[Enzo]

Exactly. There is the instant death, skin melts off your bones stuff close in, but the shock front goes for a LONG way. Flying glass and debris would kill you or harm you just as with a tornado.

I am of that era too. They were called "duck and cover" drills, and there was even a catchy tune to go with it.

We had to do duck and cover drills, diving under our desks, but we also drilled marching out into the hallway, crouching on the floor along the hallway sides. Desk hiding was what you did if you saw the "bright flash" outside. You had a few seconds to duck and cover. But if there was an attack on the way, but the bombs had not gone off, we filed into the hall. That put the cinder block wall between us and the windows.

Buildings had "fallout shelter" signs on them, meaning in case of attack, you could go into that place and there would be a basement room you could be "safe" in. It had survival food and water supplies stocked...in case. Could be public buildings, banks, private businesses, office buildings, they were all over.

Radios all had a little Civil Defense triangles at 640 and 1240 on the AM radio dial. In case of attack, you tuned to those stations for news and instructions. Local stations were equipped to change to those frequencies in case of attack.


We also had to recite the pledge of allegiance every day as well as the Lord's Prayer. Public schools. I do remember when they added the "under god" phrase to the pledge. 1954.

[Leo_Gnardo]

Radios all had a little Civil Defense triangles at 640 and 1240 on the AM radio dial. In case of attack, you tuned to those stations for news and instructions.

Ah, the CONELRAD frequencies. Even on your car radio, in case you zoomed out to pick up some burgers & beer for a last minute stockup of the home bomb shelter.

In elementary school they used to parade the kids into basement corridors during air raid exercises. It wasn't exactly pee cee for second graders but by that time we all knew the drill: "put your head between your legs and kiss your ass goodbye." I have to give JFK credit for telling Khruschev to pick up his missiles from Cuba, or else. Things settled down real quick after that.

[Mike Sulzer]

So anyway, is there any real reason for not using a silicon diode, or diodes, in a bias supply? is there any reason for not just "completing the bridge" in the full wave high voltage supply, whether or not you are using silicon in the positive supply (if you do not have a lower ac voltage handy)? You only need a tiny current, and you can use a low current voltage divider first thing so that the filter capacitor need not be rated at HV.

[Justin Thomas]

No, just thinking up dumb ideas to use extra tubes... And it seems everyone else is having some fun, so it's all good.

Justin

[Mike Sulzer]

No, just thinking up dumb ideas to use extra tubes... And it seems everyone else is having some fun, so it's all good.

Justin

Yes, fun is good!

[Leo_Gnardo]

So anyway, is there any real reason for not using a silicon diode, or diodes, in a bias supply? is there any reason for not just "completing the bridge" in the full wave high voltage supply, whether or not you are using silicon in the positive supply (if you do not have a lower ac voltage handy)? You only need a tiny current, and you can use a low current voltage divider first thing so that the filter capacitor need not be rated at HV.

"Use up the oddball tubes" yes, but as you've surely encountered Mike, in Audio Asylum, Glass Audio & Audio Amateur, etc, some builders are searching for the sound with their transmitter-tubed, single-ended, oil cap filtered, back biased & other unusual amp topologies. Sometimes it's just an exercise in "see what I can do", and I'm sure in some cases they come up with splendid sounding equipment along with that "built it myself" satisfaction.

[Justin Thomas]

Then there's the @$&#ing @$&#er, made by Rob Hull, I think... something like 27 tubes, all for TV/radio, and I can't find a sound clip that's believable anywhere. Nobody is sure if it's a joke or not!

I <DO> have a NOS pair of RCA 807s, that I'd like to make something nifty out of... Maybe later. Don't want to do single-ended with those.

Justin

[Leo_Gnardo]

Then there's the @$&#ing @$&#er, made by Rob Hull, I think... something like 27 tubes, all for TV/radio, and I can't find a sound clip that's believable anywhere. Nobody is sure if it's a joke or not!

I <DO> have a NOS pair of RCA 807s, that I'd like to make something nifty out of... Maybe later. Don't want to do single-ended with those.

Justin

@$&#ing @$&#er apparently was a joke, can't say I've heard it myself but the reviews were that it was audio garbage. Unless you really want to use heptode RF mixers for audio, why bother, there's much better tubes in the lineup of usual suspects. Thanx hevvins this did not start a trend.

I did get to work on a newish amp that used 807's a couple years ago. They'll take a lot, especially if you cool them with a fan (or immersed in oil bath so I've heard). Amp's owner was chuffed because he thought he had some mondo big power thing, what with the flying leads to top caps and all. "Hey these are radio transmitter tubes (!) dont'cha know." Just wasn't quite cutting it soundwise at gigs although it was a handsome combo build. I metered it at a whopping 9 watts at clip - no wonder - and the B+ supply was more or less borrowed from late 40's, early 50's design and specs. Hey with 325V or so on the plates, what can you expect? So, what he had was more or less an early GA-20, in a fancier box.

[Justin Thomas]

Well, <I> could have used it, as a "special effect" for sure. When your specialty is Zombie-Martian-Vampire-Sonic-Apocalypse-From-Venus, the amp is right up my alley...

Justin