Dave VanHorn wrote:

Some also implemented synchronus rectification!

Well, that's my point!

Some designs used tube rectifiers on the outputs, but later on, they added
another set of contacts on the vibrator that did the rectification.

It turns out that synchronous rectifiers were an earlier setup. They tended to
generate lots of hash, so they were pretty well superseded by tube rectifiers
in later applications. All of the vacuum tube receivers I ever worked on in
cars used the tube type rectifier. That would be mid-50's to mid-60's. As I
recall, they ran at 115 Hz.

I still have a brute force vibrator supply I built around 1955. Output is 400
volts, 150 ma. The transformer is a Hammond 286X60 with both low voltage & 115
volt primaries. Input is 6 volts, since that was in my ride of the time I built
this beast. It needs very thick copper for the LT supply. The Vibrator is an
ATR 611 with a dual set of primary contacts to handle the large currents
involved. Rectifiers are a pair of 6AX4 Damper Diodes. Obviously, any of the
five volt rectifiers would have been out of place in this application. I used a
4-prong plug as an interlock so that only one of the primaries could be run at
any time. Tuning the HV secondary with a suitable cap is important to get good
commutation at the vibrator contacts. Easy to do that with a scope.

I considered replacing the vibrator with a pair of 2N1100's but by that time my
ride was running on 12 volts.

The vibrator runs at 60 Hz so we have useful AC available as well & I often ran
an amp & record changer on it where there was no power. To bad the transformer
is wound with a 6 volt primary rather than 12 volts. But from what I read,
pretty soon mobile will be 36/42 volts to handle the much larger loads these
daze.

Cheers, John Stewart

Now we
do that in solid state, at 500kHz or better, instead of 50-60 Hz

We now have an idea of your age John (I'm 53).
Those were the days - with vibrator inverters and either cold cathode
rectifiers (that had a nice glow) or selenium stacks.
Might be old school but at least a tech could see the parts without a
magnifier.
Oh well, time to get back to working with my .5mm pitch ICs (where did I put
the magnifier...)
Oppie

"John Stewart" wrote in message
...
Dave VanHorn wrote:

Some also implemented synchronus rectification!

Well, that's my point!

Some designs used tube rectifiers on the outputs, but later on, they
added
another set of contacts on the vibrator that did the rectification.

It turns out that synchronous rectifiers were an earlier setup. They
tended to
generate lots of hash, so they were pretty well superseded by tube
rectifiers
in later applications. All of the vacuum tube receivers I ever worked on
in
cars used the tube type rectifier. That would be mid-50's to mid-60's. As
I
recall, they ran at 115 Hz.

I still have a brute force vibrator supply I built around 1955. Output is
400
volts, 150 ma. The transformer is a Hammond 286X60 with both low voltage &
115
volt primaries. Input is 6 volts, since that was in my ride of the time I
built
this beast. It needs very thick copper for the LT supply. The Vibrator is
an
ATR 611 with a dual set of primary contacts to handle the large currents
involved. Rectifiers are a pair of 6AX4 Damper Diodes. Obviously, any of
the
five volt rectifiers would have been out of place in this application. I
used a
4-prong plug as an interlock so that only one of the primaries could be
run at
any time. Tuning the HV secondary with a suitable cap is important to get
good
commutation at the vibrator contacts. Easy to do that with a scope.

I considered replacing the vibrator with a pair of 2N1100's but by that
time my
ride was running on 12 volts.

The vibrator runs at 60 Hz so we have useful AC available as well & I
often ran
an amp & record changer on it where there was no power. To bad the
transformer
is wound with a 6 volt primary rather than 12 volts. But from what I read,
pretty soon mobile will be 36/42 volts to handle the much larger loads
these
daze.

Cheers, John Stewart

Now we
do that in solid state, at 500kHz or better, instead of 50-60 Hz

Oppie wrote:

We now have an idea of your age John (I'm 53).
Those were the days - with vibrator inverters and either cold cathode
rectifiers (that had a nice glow) or selenium stacks.
Might be old school but at least a tech could see the parts without a
magnifier.
Oh well, time to get back to working with my .5mm pitch ICs (where did I put
the magnifier...)
Oppie



Hmmm - Well, I still want to see your forge - and now I
want to see howinthehell you work with .5mm IC's, too!

Ed

wrote in message news:TYZKd.3957$g_3.11@trndny08...
Hmmm - Well, I still want to see your forge - and now I
want to see howinthehell you work with .5mm IC's, too!

Ed

Forge is a propane weed burner blowing into a stack of fire bricks. Also
have a coal fired forge with a variable speed forced air blower.Haven't used
that one much lately. Anvils are a 55# cast iron (harbor freight) and a 2
foot section of mainline railroad track. Will take a picture one of these
days.

Fine pitch IC work is done with a hot air rework station, solder paste and a
shot of scotch to calm the hands. It's tricky but do-able. use a syringe to
lay down a bead of the paste (finely powdered solder in a flux paste), apply
the chip and pre-heat to 150C. Solder paste begins to liquefy the flux but
the solder is still below the melting point. The flux wets the surfaces.
surface tension should be pulling the leads to the center of the pads. Just
verify alignment and then go over the joints with a small hot air pencil tip
(~200C). Solder immediately liquefies and flows. Follow with a controlled
rate cooling, inspect, clean (if required. I use no-clean flux) and inspect
again.

Desoldering can be done by hot air also, gently pulling at the chip with a
vacuum pick-up. Another way is to use a very low temperature alloy that
melts at 150C and alloys with the existing solder to float it loose at the
lower temperature. A bit expensive and mote time consuming but much easier
on the boards.
Check out http://www.zephyrtronics.com/

Then we go to lead free which has almost no safety margin between the
temperature that the solder melts and the chips/board get cooked. yuk!

Oppie wrote:

wrote in message news:TYZKd.3957$g_3.11@trndny08...


Hmmm - Well, I still want to see your forge - and now I
want to see howinthehell you work with .5mm IC's, too!

Ed



Forge is a propane weed burner blowing into a stack of fire bricks. Also
have a coal fired forge with a variable speed forced air blower.Haven't used
that one much lately. Anvils are a 55# cast iron (harbor freight) and a 2
foot section of mainline railroad track. Will take a picture one of these
days.

Fine pitch IC work is done with a hot air rework station, solder paste and a
shot of scotch to calm the hands. It's tricky but do-able. use a syringe to
lay down a bead of the paste (finely powdered solder in a flux paste), apply
the chip and pre-heat to 150C. Solder paste begins to liquefy the flux but
the solder is still below the melting point. The flux wets the surfaces.
surface tension should be pulling the leads to the center of the pads. Just
verify alignment and then go over the joints with a small hot air pencil tip
(~200C). Solder immediately liquefies and flows. Follow with a controlled
rate cooling, inspect, clean (if required. I use no-clean flux) and inspect
again.

Desoldering can be done by hot air also, gently pulling at the chip with a
vacuum pick-up. Another way is to use a very low temperature alloy that
melts at 150C and alloys with the existing solder to float it loose at the
lower temperature. A bit expensive and mote time consuming but much easier
on the boards.
Check out http://www.zephyrtronics.com/

Then we go to lead free which has almost no safety margin between the
temperature that the solder melts and the chips/board get cooked. yuk!




Great info - thanks! The web site white papers are very
interesting. For example - who knew about lead percipitation?
I know you didn't buy the SMT tools at Brewer's Hardware!
I've filed down soldering iron tips for the larger SMT,
but .5 mm is a challenge I haven't tried. And the closest
I've been to a forge was in Mystic - as I recall, somewhere
near the aquarium. I really enjoyed watching the demonstration.
The blacksmith made a hinge. Amazing.

Ed

That wouldn't be Brewer's hardware in Mamaroneck, NY would it?
I'm in White Plains, myself and apprenticed as a blacksmith at the Van
Cortlandt Manor historical restoration in Croton.
Was walking the other day and saw an elaborate iron gate. People must have
thought me nuts (or more so than usual) as I examined every joint, bend and
flare and tried to imagine how it was constructed.
I met the resident blacksmith from Mystic Seaport at a blacksmithing show in
Massachusetts. The show is open to the public and is June 18&19.
http://www.hancockshakervillage.org/...html#ageofiron
Oppie

wrote in message
news:rEYNd.25086$QS5.15306@trndny06...
Great info - thanks! The web site white papers are very
interesting. For example - who knew about lead percipitation?
I know you didn't buy the SMT tools at Brewer's Hardware!
I've filed down soldering iron tips for the larger SMT,
but .5 mm is a challenge I haven't tried. And the closest
I've been to a forge was in Mystic - as I recall, somewhere
near the aquarium. I really enjoyed watching the demonstration.
The blacksmith made a hinge. Amazing.

Ed

Oppie wrote:

That wouldn't be Brewer's hardware in Mamaroneck, NY would it?


Yes - that's it. I'm in Harrison. I *think* we ran into each other once
at Brewer's. Did you ever go there with a catalog of old tools? I
chatted with someone there who collected old tools and who had
a forge. If it was you, you were showing the catalog to one of
the Brewer's employees - maybe Murph, but I don't recall.

I'm in White Plains, myself and apprenticed as a blacksmith at the Van
Cortlandt Manor historical restoration in Croton.
Was walking the other day and saw an elaborate iron gate. People must have
thought me nuts (or more so than usual) as I examined every joint, bend and
flare and tried to imagine how it was constructed.
I met the resident blacksmith from Mystic Seaport at a blacksmithing show in
Massachusetts. The show is open to the public and is June 18&19.
http://www.hancockshakervillage.org/...html#ageofiron
Oppie



Thanks for that! It would be fascinating to see that - I loved the
demo at Mystic. It seems impossible to make such beautiful and
intricate things with a hammer and hot iron. But when you watch,
magic happens.

Ed