On Sat, 7 Feb 2009 04:59:27 +0000 (UTC), David Lesher
wrote:


I've never seen a vibrator supply that generated 60 Hz./120VAC. The
vibrator contacts could not handle a lot of current, so I'm dubious as to
this use.

Most made ~100+ hz that fed a small xfmr to make plate voltage to the
tubes.

Right, which is why you usually used a Motor-Generator style rotary
converter to get bomb-proof operation making mass quantities of 120
VAC (more or less) at 60 Hz (more or less) for lights, plugs, motors,
etc. It's fairly easy to build a compound wound 1/4 to 1/2 HP 12V
motor that would hold appx. 3600 RPM with varying loads, and a small
two-pole alternator on the same shaft.

OK, I do know of one exception.....a long time ago. In the early days of
geranium power transistors you could buy power capacity, or gain; but not
both. [It took silly-cone ones, years later, to put this issue to bed.]

So Lee, a friend of mine, a designer of many things inc. larger invertors
at Lorain Products, had an engineer friend Steve who wanted to make his
own ~~200W 120VAC invertor.

Steve could have used an oscillator, a few stages of gain, and then
the power transistors. But he wimped out -- he used a vibrator that
then directly drive the output transistors. Lee was outraged at such
a ..rotten.. design; when he wound and coated the transformers for Steve,
he wrote RTNVTR on the iron before sealing them.

It worked, it ran, and Lee still hated it.

Then Phil borrowed it for National Guard "summer camp.." One day, when
Phil was sleeping in [no surprise there.....], two alleged buddies
borrowed it so the one could shave.

Stupid 1: "But it's 12 volts; where will we get that?"

Stupid 2: "Simple, jeeps..."

S1: "But that's 6 volts....

S2: "I know, you dummy... we'll put 2 jeeps in series. I know
all about this electricity stuff..."

But, as those of you with some years may know; while cars of that era
were 6 volts; military jeeps of the 50's/60's were not -- they were
...24 volt...


24+24 =

In the words of one of the Stupids, the shaver "made a noise like a jet
airplane" and stopped after a few seconds, when the invertor input fuse
blew. It was fine with a new fuse, but for some reason, the shaver never
ran again...

And for anyone who knows... ;-)

Lorain built lots of gear for telephone switchrooms, and they run
-48V DC native. With two Military Jeeps as the power source, he could
have brought one of the pre-made (not custom) CO Power inverters.

-- Bruce --