Hello, Roy.  You were first to respond.

 JH> I have (or had) this "Auto Stereo Home Adapter" box, rated at
 JH> 115VAC, 12-14VDC, 3 amps continuous, 5 amps switching.

 JH> I ended up blowing it up - - I'll tell about that later.  Took it
 JH> apart, and the only thing in there which could possibly be a
 JH> rectifier is this lightbulb-looking thing, with 2 bare leads out of
 JH> the bottom of the glass, and wired to the circuit board.  I've seen
 JH> one of these before, now over 40 years ago, and it was on a little
 JH> 6V trickle charger, and I ended blowing that sucker up too, while I
 JH> was still in highschool.

 JH> My questions - -
 JH> 1.  What the heck are these bulb things, and how much would a
 JH> replacement for the unit at hand cost?

 RJT> It looks like a light bulb?  Clear glass?  Can you describe anything
 RJT> about the innards?

Bulb thing is about 1- 1/2" long and about 3/8" diameter. Clear glass,
with kind of a strip of metal looking thing in there maybe about 1/16"
wide where you'd expect a filament. It is bent in a "u" shape and maybe
total length of that is about 1/2".

(ed. note -  since you don't seem to know about the kind of unit I'm
talking about, you're maybe working toward some sort of a consolation
prize)

 JH> 2.  How can a rectifier with only 2 leads give good enough DC to
 JH> run an auto stereo back in the home, without a lot of hum.

 RJT> Good question!

I probably won't hold that one against you - - after all, lots of  "all
American five" radios worked ok with only a single wave rectifier.
BUT -  I still would like to know how these bulb rectifier things with
only two leads work.

 JH> 3. Should I pitch the thing, or could maybe some large diode or
 JH> diodes be added, which would make it useable again?

 RJT> Cheap and simple -- get one of those 25A bridges from radio shack,  and
 RJT> bolt that puppy to some metal to draw off heat.  I have one PS I built
 RJT> for a bench supply,  uses a 4A transformer and a 3A regulator (TO-3
 RJT> package),  but the original "6A" rectifier didn't last. 
So I put one
 RJT> of those heavier-duty units in there.  I shouldn't ever really expect
 RJT> RS stuff to meet their specs,  but it's awfully convenient sometimes.
 RJT> :-)

I'll have to post a circuit diag of the thing and do some more study
before I invest to put a bridge rectifier in place of a single wave job.
Sounds like new bridge, heatsink, hardware and etc would now cost maybe
$10? Mayhap too much of an investment in this oldie.

IMO, buying at RS is convenient, but expensive, kinda like buying a
large bag of potato chips at a convenience store -  pay maybe 3x too
much, but instant gratification..

 JH> FWIW, in desperation, after probs with the riding mower, I used
 JH> this unit for a battery charger.  It worked OK, and put some charge
 JH> on that there lead acid battery, but I blew it up and 'let some
 JH> smoke out" when I tried to crank the mower while this makeshift
 JH> "charger" was still attached.

 RJT> Heh.

Yep.  I was in a hurry to get that mower restarted, and made a
big mistake.

 RJT> I have a number of battery chargers around here that have bad diodes,
 RJT> probably from similar causes.  Though a number of them seem to be rated
 RJT> for surges of a LOT of amps for fairly short periods of time (30
 RJT> seconds or whatever).

No rectifier bulbs in there?  Best I can tell, these bulb types were
superseded by the Selenium type rectifiers by late 1950's to 1960.
Maybe before your time?

 RJT> Speaking of battery chargers,  this reminds me of one that my
 RJT> grandfather used to have.  The rectifier in that one did look like a
 RJT> light bulb,  only it also had a wire coming out of the top.  That was a
 RJT> mercury vapor rectifier,  and I haven't seen one of those since I was a
 RJT> kid.
 RJT> If that's what it is,  good luck in finding a replacement.

AFAICT, that was the Tungar type which Tom W. mentioned.  3 leads min.
Tungar was just a trademark name, by GE or somebody.  Pix of those old
types fairly easy to find with google search on Inet.

With a little research, I see that there was another kind, with
tungsten filament and Argon gas, but I still haven't found how any of
those may have worked with only two leads exiting the bulb, or if that
is what is/was here.

- - -  JimH.



... "Bother!" said Pooh, as he saw the sparks and smelled the smoke.
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