On Wednesday, February 26, 2014 9:45:30 AM UTC-5, Jim Wilkins wrote:
wrote in message

...



Hello Jim, I don't know about the mastech switching supplies. But
the linear supplies have a "feature" that disables the output if the
load is too small... It won't source current into a dead short.
However if you send an email to Mastech they'll tell you which diode
to 'snip' to disable this "feature".
And then it's a pretty nice supply for the money.
(we resell a one of the Mastech.)



George H.



=====================

This PS-305DM which I bought locally is branded "Option Tools". It
just forced 0 to 5A into a dead-short dual banana jumper with the
output voltage at 24mV (jumper removed).


What does Mastech say about switching ranges with the 1A/5A pushbutton
while under load?

Hmm is the PS-305dm a switcher or linear? (I went to a few web pages but couln't tell.)

I only really know about the mastech linear supplies.
this one (30 V at 5A) has no switch,
http://www.mastechpowersupply.com/dc...5d/prod_3.html

We use their 50V 3A linear supply. It would 'crap out' with a load of 5 ohms or less.

George H.

jsw

On Wednesday, February 26, 2014 10:15:53 AM UTC-5, wrote:
On Wednesday, February 26, 2014 9:45:30 AM UTC-5, Jim Wilkins wrote:

wrote in message
snip

Hmm is the PS-305dm a switcher or linear? (I went to a few web pages but couln't tell.)

I only really know about the mastech linear supplies.
this one (30 V at 5A) has no switch,

http://www.mastechpowersupply.com/dc...5d/prod_3.html


We use their 50V 3A linear supply. It would 'crap out' with a load of 5 ohms or less.



George H.



jsw

OK just say this on the mastech site.
http://www.mastechpowersupply.com/dc.../prod_170.html

It appears that the hi/lo switch is an evolving "feature".
George H.

"Larry Jaques" wrote in message
...
On Wed, 26 Feb 2014 08:34:53 -0500, "Jim Wilkins"
wrote:

"Ignoramus9393" wrote in message
om...
On 2014-02-26, Larry Jaques
wrote:
On Tue, 25 Feb 2014 09:19:59 -0500, "Jim Wilkins"
wrote:


Frozen into the shed, eh? Talking with some of you guys reminds me
of
why I enjoy, so very much, living here in a more temperate climate.

Winter is the easiest time for me, no bugs, few outdoor chores,
cooking and boiling-hot water are free and raw vegetables keep in the
garage. Laundry dries on the line nearly as quickly as in summer
because the humidity is low, 44% right now. My house will remain at
least 30F warmer than outdoors without a fire during a sunny day.

Cranking speed doesn't affect the resistance reading since the
megger's meter senses and displays the ratio of applied voltage to
resulting current, R = E / I.

Oh, so that's what those cranks do. It's a little generator to
create
its own E for the I.

It's for safety; if you get shocked you stop cranking. They have a
centrifugal clutch that limits the maximum RPM and voltage. The
shorted output current on this one is only 1mA but if you are using it
to reform an old high-voltage electrolytic cap you can still get hurt.
I was nailed by 10uF at 800V once and don't care to repeat it.

jsw

wrote in message
...
On Wednesday, February 26, 2014 9:45:30 AM UTC-5, Jim Wilkins wrote:
=====================

This PS-305DM which I bought locally is branded "Option Tools". It
just forced 0 to 5A into a dead-short dual banana jumper with the
output voltage at 24mV (jumper removed).


What does Mastech say about switching ranges with the 1A/5A
pushbutton
while under load?

Hmm is the PS-305dm a switcher or linear? (I went to a few web
pages but couln't tell.)

I only really know about the mastech linear supplies.
this one (30 V at 5A) has no switch,
http://www.mastechpowersupply.com/dc...5d/prod_3.html

We use their 50V 3A linear supply. It would 'crap out' with a load
of 5 ohms or less.

George H.

jsw

Mine looks like this
http://www.mastechpowersupply.com/dc.../prod_170.html
except it has mA under the A, and resolves to 1mA in the Low, 0-1A
range. The control decal is yellow. It's heavy enough to be a linear
and a relay clicks several times as I turn the voltage up.
jsw

On Wed, 26 Feb 2014 05:54:28 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

Putting a full wave bridge in place of a half wave selenium will cause
overcharging - the voltage will be increased by virtue of full wave
rectification, AND lower voltage drop of Si over Selenium

Clare, you apparently know something about electronics, but also
obviously have never peeked inside a commercial battery charger. Pretty
much everything on the market has (and has _always_ had) a full-wave
center-tapped arrangement.

I've worked as a mechanic for many years, and have run and repaired
battery chargers much older than myself - MANY of which had simple
half wave rectifiers.
And then the "home" battery chargers - those that used Selenium or
copper oxide rectifiers - were ALL half wave. I replaced a few with
full wave bridges and they would boil a battery dry in a heartbeat.

So, no... it won't cause overcharging. The lower voltage drop across the
diodes MIGHT, but most chargers with selenium rectifiers didn't have any
particular voltage control, anyway. They were designed to charge until
you removed them. The charge tapered off with time, of course, but never
stopped... those units hardly ever were made to go into 'float' after
charging, and even then, only high-priced professional chargers did that.

They were designed to charge at about 18 volts open circuit on the
high current setting, and about 14 or 15 on the low current setting -
and the resistance of the circuit (largely the rectifier on the old
seleniums) helped limit the charging current when the battery was
taking a heavy charge.

Our old Marquette and Allen chargers ( or was it the "silver beauty?)
had a timer for the high charge, and a low charge that stayed on after
the timer shut off if selected.

Then there was the "constant current" slow charger that could charge
from 6 to 60 cells at a time - all in series.

And THEN, they did it with a current relay, not with electronics.


Lloyd

fired this volley in
:

And then the "home" battery chargers - those that used Selenium or
copper oxide rectifiers - were ALL half wave. I replaced a few with
full wave bridges and they would boil a battery dry in a heartbeat.


That's pure BS, Clare. I've also used and repaired battery chargers for
nigh-on 52 years. They are ALL full-wave center-tapped, except for those
teensy little 2A maintenance chargers.

You either aren't saying what you mean, or don't understand a full-wave
rectifier like you think you do.

You can get full-wave without a 'bridge' -- just TWO diodes... and that
ain't half-wave.

Lloyd

On Tuesday, February 25, 2014 7:43:01 PM UTC-5, Clare wrote:


Putting a full wave bridge in place of a half wave selenium will cause

overcharging - the voltage will be increased by virtue of full wave

rectification, AND lower voltage drop of Si over Selenium

I am confused. How is the voltage increased by the virtue of full wave rectification? I can see the current increased, but not the voltage. Silicon diodes do have less voltage drop than selenium diodes. It has been way too many years since I had anything to do with selenium rectfiers. As I remember the voltage drop depended on how many plates there were used in order to get the necessary reverse breakdown. So for a 12 volt battery charger, not that big a deal.

In any case using silicon diodes in place of selenium should be no big deal in Tom's case where he uses the repaired battery charger to partially charge a dead battery and then changes to his new modern electronic charger.


I am off to refresh my memory on selenium rectifiers. As I remember the navy purged all the selenium rectifiers from their equipment back in about 1960, because the fumes from a burned out selenium rectifier were poisonous.

Dan

On Wed, 26 Feb 2014 05:54:28 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

Putting a full wave bridge in place of a half wave selenium will cause
overcharging - the voltage will be increased by virtue of full wave
rectification, AND lower voltage drop of Si over Selenium

Clare, you apparently know something about electronics, but also
obviously have never peeked inside a commercial battery charger. Pretty
much everything on the market has (and has _always_ had) a full-wave
center-tapped arrangement.

So, no... it won't cause overcharging. The lower voltage drop across the
diodes MIGHT, but most chargers with selenium rectifiers didn't have any
particular voltage control, anyway. They were designed to charge until
you removed them. The charge tapered off with time, of course, but never
stopped... those units hardly ever were made to go into 'float' after
charging, and even then, only high-priced professional chargers did that.

And THEN, they did it with a current relay, not with electronics.


Lloyd

Gee... don't battery chargers have current adjusting knobs on them any
more.

Mine must be an antique, or something. Got a selector switch, 12 or 24
volt battery, and another knob to select the amount of charging
current and even an ampere meter to tell you how much you are
charging.
--
Cheers,

John B.

On Wed, 26 Feb 2014 18:07:01 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

And then the "home" battery chargers - those that used Selenium or
copper oxide rectifiers - were ALL half wave. I replaced a few with
full wave bridges and they would boil a battery dry in a heartbeat.


That's pure BS, Clare. I've also used and repaired battery chargers for
nigh-on 52 years. They are ALL full-wave center-tapped, except for those
teensy little 2A maintenance chargers.

You either aren't saying what you mean, or don't understand a full-wave
rectifier like you think you do.

You can get full-wave without a 'bridge' -- just TWO diodes... and that
ain't half-wave.

Lloyd
I know full and half wave. Without a center tapped transformer you
need a bridge for full wave. That's 4 diodes. With a center tap, you
need 2 diodes and you have full wave. With only one diode and one
winding you have half wave.. If you put a single diode on a center
tapped transformer and don't use the center tap, it's hald wave.
Anything using a single standard tungar tube was half wave (and yes,
I've used and worked with Tungar chargers). There were full wave
tungar bulbs for center tapped transformers,(twin anode) but they were
high voltage low current devices, generally not suitable for
automotive battery charger circuits. Some chargers were multi-tube
units as well, but in my experience they were not very common (I've
never used one or seen one in use).

Selenium rectifiers have been used in battery chargers for decades,
and are still common on the cheap home chargers. Single plate seleiums
are good for 25PIV, have a 1 volt per plate forward drop, and have
regulating characteristics that make them a good choice for a
low-compnent-count charger. Copper oxide was used for the same
purpose quite a few years back, but they are less efficient (although
lot more efficient than Tungars).
I've pitched quite a few 6-10 amp chargers with single plate seleniums
over the last 20 or more years - so they are still pretty common..
Some use the chassis as the heat sink AND cathode - with just a rivet
through the wire terminal, plate, and chassis.
Same construction on some of the full wave center tapped chargers.

Don't set one of those on the fender of a positve ground car!!!!

I've also tried replacing the seleniums with silicon stud-mounts -
with poor results. A single silicon diode with 25 or 50 PIV rating has
about a .7 volt forward drop, so you would thing the charge rate would
be pretty well the same - but I found they tried to charge at a higher
current - causing the current interupter (breaker) to cycle - and
putting in a bridge raised the voltage. Into a straight resistive load
a full wave circuit produces very close to double the voltage a half
wave puts out. In a capacitive circuit it is a bit closer, IIRC. - but
still no good for a simple battery charger.

The pulsing of a half wave rectifier in a battery charger, according
to some people, has less of a polarizing effect - making for more
efficient? charging because the plates don't get covered with bubbles
of H and O2 as much. Works a bit like the "desulphators"

Anyway - suffice it to say there have been ALL KINDS of different
battery chargers - with all kinds of circuits, used over the decades.
From terribly crude, badly regulated to very refined and well
regulated - using everything from Fero-resonant regulation to
mechanized carbon pile regulators to fully electronic regulation -
solid state and otherwise.

My favorite charger was a dynamotor setup - 1/2 horse electric motor
running an old autolite generator with 2 voltage regulators on it and
a switch to connect either the 6 volt or the 12 volt regulator.. It
was one you could connect and walk away, knowing the battery would be
fully charged and not overcharged when you returned.

Not nearly as noisy and stinky as the gasoline powered unit used for
charging and boosting cars on the used car lot (3hp Briggs and a
motorola? alternator)

On Wed, 26 Feb 2014 16:27:29 -0800 (PST), "
wrote:

On Tuesday, February 25, 2014 7:43:01 PM UTC-5, Clare wrote:


Putting a full wave bridge in place of a half wave selenium will cause

overcharging - the voltage will be increased by virtue of full wave

rectification, AND lower voltage drop of Si over Selenium

I am confused. How is the voltage increased by the virtue of full wave rectification? I can see the current increased, but not the voltage. Silicon diodes do have less voltage drop than selenium diodes. It has been way too many years since I had anything to do with selenium rectfiers. As I remember the voltage drop depended on how many plates there were used in order to get the necessary reverse breakdown. So for a 12 volt battery charger, not that big a deal.

In any case using silicon diodes in place of selenium should be no big deal in Tom's case where he uses the repaired battery charger to partially charge a dead battery and then changes to his new modern electronic charger.


I am off to refresh my memory on selenium rectifiers. As I remember the navy purged all the selenium rectifiers from their equipment back in about 1960, because the fumes from a burned out selenium rectifier were poisonous.

Dan
IIRC Half wave gives about .3 X AC voltage and full wave closer to .6
times becuse full wave puts both halves of the sine wave to work,
while half wave only uses half of it.. Can't remember it that was peak
or RMS (on the AC side).
And yes, those seleniums REALLY stunk when they let go. Selenium is a
very close relative of sulphur chemically, and selenium dioxide and
sulphur dioxide have similar smell and effect -EXTREMELY unpleasant.
And poisonous. Burns skin and mucosa - and eyes.

On Wed, 26 Feb 2014 11:38:45 -0500, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
.. .
On Wed, 26 Feb 2014 08:34:53 -0500, "Jim Wilkins"
wrote:

"Ignoramus9393" wrote in message
news:a8Wdnc2Lm9qD6JDOnZ2dnUVZ_jydnZ2d@giganews. com...
On 2014-02-26, Larry Jaques
wrote:
On Tue, 25 Feb 2014 09:19:59 -0500, "Jim Wilkins"
wrote:


Frozen into the shed, eh? Talking with some of you guys reminds me
of
why I enjoy, so very much, living here in a more temperate climate.

Winter is the easiest time for me, no bugs, few outdoor chores,
cooking and boiling-hot water are free and raw vegetables keep in the
garage. Laundry dries on the line nearly as quickly as in summer
because the humidity is low, 44% right now. My house will remain at
least 30F warmer than outdoors without a fire during a sunny day.

So at zero, you're at a toasty 30F? Wunnerful!


Cranking speed doesn't affect the resistance reading since the
megger's meter senses and displays the ratio of applied voltage to
resulting current, R = E / I.

Oh, so that's what those cranks do. It's a little generator to
create
its own E for the I.

It's for safety; if you get shocked you stop cranking. They have a
centrifugal clutch that limits the maximum RPM and voltage. The
shorted output current on this one is only 1mA but if you are using it
to reform an old high-voltage electrolytic cap you can still get hurt.
I was nailed by 10uF at 800V once and don't care to repeat it.

I got bitten by an 800v line inside a computer monitor once. That
really smarts. I could feel scar tissue in the heel of my hand for a
couple years afterward.

--
Courage and perseverance have a magical talisman, before
which difficulties disappear and obstacles vanish into air.
-- John Quincy Adams

On 2014-02-26, Ignoramus9393 wrote:
On 2014-02-26, DoN. Nichols wrote:
On 2014-02-25, Ignoramus9393 wrote:
I have a few welding rectifiers for sale, that I sold from some big
old welders. They look like this:

http://goo.gl/327zJ4

They have everything all together, heatsinking, mounting, isolation
etc. I already sold a bunch of them. I think that most buyers use them
to convert AC welders to DC welders.

O.K. That is for three phase in (via the aluminum straps which
appear to have been bent), and it is three each of forward polarity
diodes (on one plate) and of reverse polarity diodes (on the other
plate).

You can only put one phase in. No problem.

Of course.

Actually, for one phase, you can hook it up as follows:

Your in-terminals X, Y, Z, connected to single phase A and B like this:

A, B, A

In other words, one side of single phase is in the middle, and
another side of single phase is on both ends). That allows for
somewhat better cooling.

Reasonable. But given that the battery charger in question used
only two (selenium) rectifiers (and a center-tapped transformer
secondary), there is no need for the other half of the rectifier
assembly -- and it takes up space, so pull out one plate and only mount
the one which has the flavor of diodes (normal or reverse) needed by the
design of that battery charger. And with that, you probably don't even
need the insulating strips to insulate it from the chassis. Since he
said that there was only one wire going to each selenium rectifier, I
suspect that the chassis is serving as the common point of the two
rectifiers.

And -- a use for the extra rectifier place could be to swap in
one from the other plate (reverse or standard -- the opposite of what is
on the plate with the needed rectifiers) to block against reverse
connection to the battery frying the transformer or the diodes -- or
both.

Have you looked up the current rating for those diodes? Given
the cable leads instead of terminals, I suspect that it is rather
impressive. :-)

For the battery charger, you would only need one plate (which is
a function of the polarity of the original selenium rectifiers) and only
two of the three rectifiers on it. So -- just grab one of those, select
which plate has the right set of rectifiers for your needs, and either
pull out the third diode -- or leave it in there for a quick swap-in if
one fails (and trips the breaker before it cooks the other diode. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2014-02-27, wrote:
On Wed, 26 Feb 2014 18:07:01 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
m:

And then the "home" battery chargers - those that used Selenium or
copper oxide rectifiers - were ALL half wave. I replaced a few with
full wave bridges and they would boil a battery dry in a heartbeat.


That's pure BS, Clare. I've also used and repaired battery chargers for
nigh-on 52 years. They are ALL full-wave center-tapped, except for those
teensy little 2A maintenance chargers.

You either aren't saying what you mean, or don't understand a full-wave
rectifier like you think you do.

You can get full-wave without a 'bridge' -- just TWO diodes... and that
ain't half-wave.

Lloyd
I know full and half wave. Without a center tapped transformer you
need a bridge for full wave. That's 4 diodes. With a center tap, you
need 2 diodes and you have full wave. With only one diode and one
winding you have half wave.. If you put a single diode on a center
tapped transformer and don't use the center tap, it's hald wave.

If you put a single diode on a center tapped transformer, and
don't use the center tap, you are applying twice the design voltage to
the battery -- so you *will* get overcharging then for sure -- or burn
out the transformer first. :-) If you put a full wave bridge rectifier
on the unit, and still leave the center tap floating, you will have not
quite as high a voltage, but current closer to full time, and will also
overcharge.

However -- using the full-wave bridge between the center tap and
one side of the transformer will produce something closer to the design
voltage -- but you will be drawing all your current from one half of the
secondary -- and if the design is marginal, you will again burn out the
transformer. With two diodes wired as the original selenium rectifiers
were will get a little more voltage out, but not much. Probably swamped
in the loss in the transformer.

Anything using a single standard tungar tube was half wave (and yes,
I've used and worked with Tungar chargers). There were full wave
tungar bulbs for center tapped transformers,(twin anode) but they were
high voltage low current devices, generally not suitable for
automotive battery charger circuits. Some chargers were multi-tube
units as well, but in my experience they were not very common (I've
never used one or seen one in use).

Tungar is rather old technology these days. The last time I saw
those in use was in the power supply for a drive-in movie projector back
in the very early 1960s.

Selenium rectifiers have been used in battery chargers for decades,
and are still common on the cheap home chargers. Single plate seleiums
are good for 25PIV, have a 1 volt per plate forward drop, and have
regulating characteristics that make them a good choice for a
low-compnent-count charger. Copper oxide was used for the same
purpose quite a few years back, but they are less efficient (although
lot more efficient than Tungars).

Of course.

I've pitched quite a few 6-10 amp chargers with single plate seleniums
over the last 20 or more years - so they are still pretty common..
Some use the chassis as the heat sink AND cathode - with just a rivet
through the wire terminal, plate, and chassis.
Same construction on some of the full wave center tapped chargers.

Indeed -- which is why the selection of diodes with either
standard or reverse stud polarity could allow it to work closer to its
original design.

Don't set one of those on the fender of a positve ground car!!!!

It could get exciting -- especially once you scratch through the
paint. :-)

I've also tried replacing the seleniums with silicon stud-mounts -
with poor results. A single silicon diode with 25 or 50 PIV rating has
about a .7 volt forward drop, so you would thing the charge rate would
be pretty well the same - but I found they tried to charge at a higher
current - causing the current interupter (breaker) to cycle - and
putting in a bridge raised the voltage.

If as you said near the top, you were not using the center tap,
yes it would raise the voltage quite a bit. :-)

Into a straight resistive load
a full wave circuit produces very close to double the voltage a half
wave puts out.

That is, again, if you are not using the center tap. If you use
the center tap, and half of a full wave bridge (two diodes, the other
bridge output terminal not connected to anything) you will be closer to
the design voltage.

You could use the full-wave bridge between one side of the
transformer and the center tap (and leave the other side floating) your
voltage would be closer to normal.

In a capacitive circuit it is a bit closer, IIRC. - but
still no good for a simple battery charger.

No need for (filter) capacitors on a battery charger in normal
use, the battery itself sort of handles the filtering there if it is
still good.

The pulsing of a half wave rectifier in a battery charger, according
to some people, has less of a polarizing effect - making for more
efficient? charging because the plates don't get covered with bubbles
of H and O2 as much. Works a bit like the "desulphators"

Maybe. I don't know there.

Anyway - suffice it to say there have been ALL KINDS of different
battery chargers - with all kinds of circuits, used over the decades.
From terribly crude, badly regulated to very refined and well
regulated - using everything from Fero-resonant regulation to
mechanized carbon pile regulators to fully electronic regulation -
solid state and otherwise.

Quite a collection.

My favorite charger was a dynamotor setup - 1/2 horse electric motor
running an old autolite generator with 2 voltage regulators on it and
a switch to connect either the 6 volt or the 12 volt regulator.. It
was one you could connect and walk away, knowing the battery would be
fully charged and not overcharged when you returned.

Sounds interesting. Not as efficient as some other circuits,
but yes, free of overcharge. Same should be do-able with an alternator
and the appropriate regulator as well.

Not nearly as noisy and stinky as the gasoline powered unit used for
charging and boosting cars on the used car lot (3hp Briggs and a
motorola? alternator)

:-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2014-02-27, wrote:
On Tuesday, February 25, 2014 7:43:01 PM UTC-5, Clare wrote:


Putting a full wave bridge in place of a half wave selenium will cause

overcharging - the voltage will be increased by virtue of full wave

rectification, AND lower voltage drop of Si over Selenium

I am confused. How is the voltage increased by the virtue of full
wave rectification?

You missed his statement that he was ignoring the center tap, so
applying double the AC voltage to the bridge. Having the half-wave
relative to the center tap produces half the peak voltage that using a
full wave bridge with the center tap floating.

I can see the current increased, but not the
voltage.

Agreed -- until you start using the transformer's end-to-end
voltage without the center tap involved.

Silicon diodes do have less voltage drop than selenium diodes.
It has been way too many years since I had anything to do with selenium
rectfiers. As I remember the voltage drop depended on how many plates
there were used in order to get the necessary reverse breakdown. So for
a 12 volt battery charger, not that big a deal.

Agreed -- a single plate per side of the transformer.

In any case using silicon diodes in place of selenium should be no big
deal in Tom's case where he uses the repaired battery charger to
partially charge a dead battery and then changes to his new modern
electronic charger.

Agreed.

I am off to refresh my memory on selenium rectifiers. As I remember
the navy purged all the selenium rectifiers from their equipment back in
about 1960, because the fumes from a burned out selenium rectifier were
poisonous.

And nasty smelling, too, even with a relatively small one. I
never used a large enough one for the fumes to be a problem -- and I was
a kid (thus indestructible) back then anyway. :-)

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2/26/2014 10:11 PM, Larry Jaques wrote:
I got bitten by an 800v line inside a computer monitor once. That
really smarts. I could feel scar tissue in the heel of my hand for a
couple years afterward.

--

Come on now...the scar tissue on your hand ISN'T from an electric shock,
is it.

On 2/26/2014 7:27 PM, wrote:

In any case using silicon diodes in place of selenium should be no
big deal in Tom's case where he uses the repaired battery charger to
partially charge a dead battery and then changes to his new modern
electronic charger.


Yep, I trust the electronic charger not to fuch-up my battery!

"Larry Jaques" wrote in message
...
On Wed, 26 Feb 2014 11:38:45 -0500, "Jim Wilkins"
wrote:


Winter is the easiest time for me, no bugs, few outdoor chores,
cooking and boiling-hot water are free and raw vegetables keep in
the
garage. Laundry dries on the line nearly as quickly as in summer
because the humidity is low, 44% right now. My house will remain at
least 30F warmer than outdoors without a fire during a sunny day.

So at zero, you're at a toasty 30F? Wunnerful!

We drop to 0 at night but haven't had a day that stayed that cold. If
the house was at 60F in the morning and the day never rose above 15F
the house might lose 2-3 degrees during the day without a fire. It's
hard to measure accurately because I raise the thermometer about 1 to
1.5 degree from normal activity, making breakfast and running the
computer, and the basement holds and slowly releases a lot of wood
stove heat. My preliminary test runs revealed a few things to change
before making better measurements.

I do know that a single 700W baseboard heater will hold the house well
above freezing without costing a lot. That was the important question.
The insurance company wanted to be sure I had automatic backup heat,
not just the stove.

This is a standard housing-development electrically heated home from
1970 and about all I've done is reduce heat loss through the doors and
windows and add more attic insulation.

jsw

On Thu, 27 Feb 2014 08:00:06 -0500, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
.. .
On Wed, 26 Feb 2014 11:38:45 -0500, "Jim Wilkins"
wrote:


Winter is the easiest time for me, no bugs, few outdoor chores,
cooking and boiling-hot water are free and raw vegetables keep in
the
garage. Laundry dries on the line nearly as quickly as in summer
because the humidity is low, 44% right now. My house will remain at
least 30F warmer than outdoors without a fire during a sunny day.

So at zero, you're at a toasty 30F? Wunnerful!

We drop to 0 at night but haven't had a day that stayed that cold. If
the house was at 60F in the morning and the day never rose above 15F
the house might lose 2-3 degrees during the day without a fire. It's
hard to measure accurately because I raise the thermometer about 1 to
1.5 degree from normal activity, making breakfast and running the
computer, and the basement holds and slowly releases a lot of wood
stove heat. My preliminary test runs revealed a few things to change
before making better measurements.

That's good!


I do know that a single 700W baseboard heater will hold the house well
above freezing without costing a lot. That was the important question.
The insurance company wanted to be sure I had automatic backup heat,
not just the stove.

I ripped out the 240v baseboard heaters and plopped down $6k for a
Carrier Infinity (96% efficient) heater and A/C unit shortly after I
moved into this 1966 era home. The single-glazed aluminum-framed
windows went and Low-E dual-paned vinyl windows really quieted things
down and warmed things up for me.


This is a standard housing-development electrically heated home from
1970 and about all I've done is reduce heat loss through the doors and
windows and add more attic insulation.

You're better insulated than I am. The last time the power was off in
Winter, I think I lost 1.5F per hour.

One of these days, I'll pull the top clapboards off, drill holes, and
pump the walls full of glass. I put R-38 under the house a few years
ago when I had it Visqueened and borated. And there's a meager 6" of
fluff in the attic. That will have to come up, too. I finally got up
there last week and got myself very sore, climbing around installing
12v wiring through the ceiling for the emergency solar lighting.

Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

--
Courage and perseverance have a magical talisman, before
which difficulties disappear and obstacles vanish into air.
-- John Quincy Adams

"Larry Jaques" wrote in message
...
On Thu, 27 Feb 2014 08:00:06 -0500, "Jim Wilkins"
wrote:


You're better insulated than I am. The last time the power was off
in
Winter, I think I lost 1.5F per hour.

One of these days, I'll pull the top clapboards off, drill holes,
and
pump the walls full of glass. I put R-38 under the house a few years
ago when I had it Visqueened and borated. And there's a meager 6"
of
fluff in the attic. That will have to come up, too. I finally got
up
there last week and got myself very sore, climbing around installing
12v wiring through the ceiling for the emergency solar lighting.

Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom
at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

I found the last heat leaks by watching the melting pattern of light
snowfall, and scanning the inside walls and ceiling with a cheap IR
thermometer. The windows glass and Mylar film reveal their temperature
to the IR thermometer by sticking on black tape.

I have a roof like that. The last time I could work comfortably in the
attic was when a fallen tree knocked a dozen large holes in the
plywood. OTOH my beer didn't slide off when I was reshingling.

My emergency solar lighting is a pair of HF solar lanterns. I really
only need to see the floor to walk around at night.

-jsw

On 27 Feb 2014 05:09:30 GMT, "DoN. Nichols"
wrote:

On 2014-02-27, wrote:
On Wed, 26 Feb 2014 18:07:01 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

And then the "home" battery chargers - those that used Selenium or
copper oxide rectifiers - were ALL half wave. I replaced a few with
full wave bridges and they would boil a battery dry in a heartbeat.


That's pure BS, Clare. I've also used and repaired battery chargers for
nigh-on 52 years. They are ALL full-wave center-tapped, except for those
teensy little 2A maintenance chargers.

You either aren't saying what you mean, or don't understand a full-wave
rectifier like you think you do.

You can get full-wave without a 'bridge' -- just TWO diodes... and that
ain't half-wave.

Lloyd
I know full and half wave. Without a center tapped transformer you
need a bridge for full wave. That's 4 diodes. With a center tap, you
need 2 diodes and you have full wave. With only one diode and one
winding you have half wave.. If you put a single diode on a center
tapped transformer and don't use the center tap, it's hald wave.

If you put a single diode on a center tapped transformer, and
don't use the center tap, you are applying twice the design voltage to
the battery -- so you *will* get overcharging then for sure -- or burn
out the transformer first. :-) If you put a full wave bridge rectifier
on the unit, and still leave the center tap floating, you will have not
quite as high a voltage, but current closer to full time, and will also
overcharge.

However -- using the full-wave bridge between the center tap and
one side of the transformer will produce something closer to the design
voltage -- but you will be drawing all your current from one half of the
secondary -- and if the design is marginal, you will again burn out the
transformer. With two diodes wired as the original selenium rectifiers
were will get a little more voltage out, but not much. Probably swamped
in the loss in the transformer.

Anything using a single standard tungar tube was half wave (and yes,
I've used and worked with Tungar chargers). There were full wave
tungar bulbs for center tapped transformers,(twin anode) but they were
high voltage low current devices, generally not suitable for
automotive battery charger circuits. Some chargers were multi-tube
units as well, but in my experience they were not very common (I've
never used one or seen one in use).

Tungar is rather old technology these days. The last time I saw
those in use was in the power supply for a drive-in movie projector back
in the very early 1960s.

Selenium rectifiers have been used in battery chargers for decades,
and are still common on the cheap home chargers. Single plate seleiums
are good for 25PIV, have a 1 volt per plate forward drop, and have
regulating characteristics that make them a good choice for a
low-compnent-count charger. Copper oxide was used for the same
purpose quite a few years back, but they are less efficient (although
lot more efficient than Tungars).

Of course.

I've pitched quite a few 6-10 amp chargers with single plate seleniums
over the last 20 or more years - so they are still pretty common..
Some use the chassis as the heat sink AND cathode - with just a rivet
through the wire terminal, plate, and chassis.
Same construction on some of the full wave center tapped chargers.

Indeed -- which is why the selection of diodes with either
standard or reverse stud polarity could allow it to work closer to its
original design.

Don't set one of those on the fender of a positve ground car!!!!

It could get exciting -- especially once you scratch through the
paint. :-)

I've also tried replacing the seleniums with silicon stud-mounts -
with poor results. A single silicon diode with 25 or 50 PIV rating has
about a .7 volt forward drop, so you would thing the charge rate would
be pretty well the same - but I found they tried to charge at a higher
current - causing the current interupter (breaker) to cycle - and
putting in a bridge raised the voltage.

If as you said near the top, you were not using the center tap,
yes it would raise the voltage quite a bit. :-)

Nope. With center tap I would use 2 - but this particular one was a
single plate unit. Using a bridge put the voltage too high,

Into a straight resistive load
a full wave circuit produces very close to double the voltage a half
wave puts out.

That is, again, if you are not using the center tap. If you use
the center tap, and half of a full wave bridge (two diodes, the other
bridge output terminal not connected to anything) you will be closer to
the design voltage.
Again, I was taliking the single plate charger. If you have a center
tapped transformer it is pretty hard to use a half wave or a bridge
properly.

And regardless, the silicon diode has NO regulation effect at all,
while a selenium plate does. The selenium plate rectifier is "softer"
than a silicone - to properly emulate a selenium rectifier you NEED to
put a low value resistor in series.

You could use the full-wave bridge between one side of the
transformer and the center tap (and leave the other side floating) your
voltage would be closer to normal.

and using a bridge on one side of a center tap would be too low to
charge the battery effectively

In a capacitive circuit it is a bit closer, IIRC. - but
still no good for a simple battery charger.

No need for (filter) capacitors on a battery charger in normal
use, the battery itself sort of handles the filtering there if it is
still good.

Like I said, the capacitive effect of the battery in the circuit
makes the voltage a bit closer to correct - but still not good enough
for a "simple" battery charger.

The pulsing of a half wave rectifier in a battery charger, according
to some people, has less of a polarizing effect - making for more
efficient? charging because the plates don't get covered with bubbles
of H and O2 as much. Works a bit like the "desulphators"

Maybe. I don't know there.

Anyway - suffice it to say there have been ALL KINDS of different
battery chargers - with all kinds of circuits, used over the decades.
From terribly crude, badly regulated to very refined and well
regulated - using everything from Fero-resonant regulation to
mechanized carbon pile regulators to fully electronic regulation -
solid state and otherwise.

Quite a collection.

My favorite charger was a dynamotor setup - 1/2 horse electric motor
running an old autolite generator with 2 voltage regulators on it and
a switch to connect either the 6 volt or the 12 volt regulator.. It
was one you could connect and walk away, knowing the battery would be
fully charged and not overcharged when you returned.

Sounds interesting. Not as efficient as some other circuits,
but yes, free of overcharge. Same should be do-able with an alternator
and the appropriate regulator as well.

Not nearly as noisy and stinky as the gasoline powered unit used for
charging and boosting cars on the used car lot (3hp Briggs and a
motorola? alternator)

:-)

Enjoy,
DoN.

On 27 Feb 2014 05:15:03 GMT, "DoN. Nichols"
wrote:

On 2014-02-27, wrote:
On Tuesday, February 25, 2014 7:43:01 PM UTC-5, Clare wrote:


Putting a full wave bridge in place of a half wave selenium will cause

overcharging - the voltage will be increased by virtue of full wave

rectification, AND lower voltage drop of Si over Selenium

I am confused. How is the voltage increased by the virtue of full
wave rectification?

You missed his statement that he was ignoring the center tap, so
applying double the AC voltage to the bridge. Having the half-wave
relative to the center tap produces half the peak voltage that using a
full wave bridge with the center tap floating.

I can see the current increased, but not the
voltage.

Agreed -- until you start using the transformer's end-to-end
voltage without the center tap involved.

Nope. You read me wrong. As explained in a previous reply

Silicon diodes do have less voltage drop than selenium diodes.
It has been way too many years since I had anything to do with selenium
rectfiers. As I remember the voltage drop depended on how many plates
there were used in order to get the necessary reverse breakdown. So for
a 12 volt battery charger, not that big a deal.

Agreed -- a single plate per side of the transformer.

In any case using silicon diodes in place of selenium should be no big
deal in Tom's case where he uses the repaired battery charger to
partially charge a dead battery and then changes to his new modern
electronic charger.

Agreed.

I am off to refresh my memory on selenium rectifiers. As I remember
the navy purged all the selenium rectifiers from their equipment back in
about 1960, because the fumes from a burned out selenium rectifier were
poisonous.

And nasty smelling, too, even with a relatively small one. I
never used a large enough one for the fumes to be a problem -- and I was
a kid (thus indestructible) back then anyway. :-)

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.


--
"A "Liberal Paradise" would be a place where everybody has
guaranteed employment,free comprehensive healthcare,
free education, free food, free housing, free clothing,
free utilities, and only Law Enforcement has guns.
And believe it or not, such a place does indeed exist . . . It's called PRISON.

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

On Fri, 28 Feb 2014 21:55:54 -0800, Gunner Asch
wrote:

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

Quit that, ya sadist bastid!


I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.

I'm not even going to blow the glass into the attic myself. It's hell
getting old, and I'm only 60! (...can't imagine living to 90...)

--
Courage and perseverance have a magical talisman, before
which difficulties disappear and obstacles vanish into air.
-- John Quincy Adams

On Sat, 01 Mar 2014 09:53:19 -0800, Larry Jaques
wrote:

On Fri, 28 Feb 2014 21:55:54 -0800, Gunner Asch
wrote:

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

Quit that, ya sadist bastid!


I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.

I'm not even going to blow the glass into the attic myself. It's hell
getting old, and I'm only 60! (...can't imagine living to 90...)

I turned 60 last November...and I purely been rode hard and put up
wet...

https://picasaweb.google.com/1040422...35856571883746
https://picasaweb.google.com/1040422...11748915222610

https://picasaweb.google.com/1040422...otosFromThe70s

Then....

https://picasaweb.google.com/1040422...78745971840962

Now....

https://picasaweb.google.com/1040422...85319252497058


Brrrrrrr!!!


--

"
I was once told by a “gun safety” advocate back in the Nineties
that he favored total civilian firearms confiscation.
Only the military and police should have weapons he averred and what did I think about that?

I began to give him a reasoned answer and he
cut me off with an abrupt, “Give me the short answer.”

I thought for a moment and said, “If you try to take our firearms we will kill you.”"

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

On Sat, 01 Mar 2014 13:58:27 -0800, Gunner Asch
wrote:

On Sat, 01 Mar 2014 09:53:19 -0800, Larry Jaques
wrote:

On Fri, 28 Feb 2014 21:55:54 -0800, Gunner Asch
wrote:

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

Quit that, ya sadist bastid!


I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.

I'm not even going to blow the glass into the attic myself. It's hell
getting old, and I'm only 60! (...can't imagine living to 90...)

I turned 60 last November...and I purely been rode hard and put up
wet...

https://picasaweb.google.com/1040422...35856571883746
https://picasaweb.google.com/1040422...11748915222610

https://picasaweb.google.com/1040422...otosFromThe70s

Then....

https://picasaweb.google.com/1040422...78745971840962

Now....

https://picasaweb.google.com/1040422...85319252497058


Brrrrrrr!!!
Gee, Gunner, you're just a kid - 2 years younger than me - and you
look OLD!!! Hard livin does that to you quicker than hard work.

And those pictures put to rest any questions about your involvement in
law enforcement.
You were a good look'n kid, gunner.

formulated on Sunday :
On Sat, 01 Mar 2014 13:58:27 -0800, Gunner Asch
wrote:

On Sat, 01 Mar 2014 09:53:19 -0800, Larry Jaques
wrote:

On Fri, 28 Feb 2014 21:55:54 -0800, Gunner Asch
wrote:

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

Quit that, ya sadist bastid!


I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.

I'm not even going to blow the glass into the attic myself. It's hell
getting old, and I'm only 60! (...can't imagine living to 90...)

I turned 60 last November...and I purely been rode hard and put up
wet...

https://picasaweb.google.com/1040422...35856571883746
https://picasaweb.google.com/1040422...11748915222610

https://picasaweb.google.com/1040422...otosFromThe70s

Then....

https://picasaweb.google.com/1040422...78745971840962

Now....

https://picasaweb.google.com/1040422...85319252497058


Brrrrrrr!!!
Gee, Gunner, you're just a kid - 2 years younger than me - and you
look OLD!!! Hard livin does that to you quicker than hard work.

And those pictures put to rest any questions about your involvement in
law enforcement.
You were a good look'n kid, gunner.

You will both have to run to catch me!
80 next August. lol

--
John G

On Sun, 02 Mar 2014 01:46:53 -0500, wrote:

On Sat, 01 Mar 2014 13:58:27 -0800, Gunner Asch
wrote:

On Sat, 01 Mar 2014 09:53:19 -0800, Larry Jaques
wrote:

On Fri, 28 Feb 2014 21:55:54 -0800, Gunner Asch
wrote:

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

Quit that, ya sadist bastid!


I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.

I'm not even going to blow the glass into the attic myself. It's hell
getting old, and I'm only 60! (...can't imagine living to 90...)

I turned 60 last November...and I purely been rode hard and put up
wet...

https://picasaweb.google.com/1040422...35856571883746
https://picasaweb.google.com/1040422...11748915222610

https://picasaweb.google.com/1040422...otosFromThe70s

Then....

https://picasaweb.google.com/1040422...78745971840962

Now....

https://picasaweb.google.com/1040422...85319252497058


Brrrrrrr!!!
Gee, Gunner, you're just a kid - 2 years younger than me - and you
look OLD!!! Hard livin does that to you quicker than hard work.

Also not getting enough sleep and having the Almost restored sailboat
present some problems on a very windy day..and put me in my place.
Thought Id fixed em all...not even close. I relearned "humility" that
day.

And those pictures put to rest any questions about your involvement in
law enforcement.

Shrug..I make it a point not to lie, either here or in the real world.
Too hard to keep em all straight..so **** it..simply tell the truth or
keep my mouth shut.

You were a good look'n kid, gunner.

Im stil a good looking kid (Grin)..when Im not having a bad day.
Least..some of the women my age think so.

Gunner tips his cap to the gent.





--

"
I was once told by a “gun safety” advocate back in the Nineties
that he favored total civilian firearms confiscation.
Only the military and police should have weapons he averred and what did I think about that?

I began to give him a reasoned answer and he
cut me off with an abrupt, “Give me the short answer.”

I thought for a moment and said, “If you try to take our firearms we will kill you.”"

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

On Sun, 02 Mar 2014 19:18:40 +1100, John G
wrote:

formulated on Sunday :
On Sat, 01 Mar 2014 13:58:27 -0800, Gunner Asch
wrote:

On Sat, 01 Mar 2014 09:53:19 -0800, Larry Jaques
wrote:

On Fri, 28 Feb 2014 21:55:54 -0800, Gunner Asch
wrote:

On Thu, 27 Feb 2014 06:30:08 -0800, Larry Jaques
wrote:


Tomorrow, I mean to go up and hook in the last line, from the
controller. My roof is 4:12, so there is only 4ish feet of headroom at
best. I don't know how many more attic trips the old bod is capable
of in the future, but it ain't many, I tell ya. sigh

So that job offer from the alarm company..you arent going to take it?

(Grin)

Quit that, ya sadist bastid!


I gave that **** up in 1994. After 17 yrs of attic climbing..I was
done with it.

I'm not even going to blow the glass into the attic myself. It's hell
getting old, and I'm only 60! (...can't imagine living to 90...)

I turned 60 last November...and I purely been rode hard and put up
wet...

https://picasaweb.google.com/1040422...35856571883746
https://picasaweb.google.com/1040422...11748915222610

https://picasaweb.google.com/1040422...otosFromThe70s

Then....

https://picasaweb.google.com/1040422...78745971840962

Now....

https://picasaweb.google.com/1040422...85319252497058


Brrrrrrr!!!
Gee, Gunner, you're just a kid - 2 years younger than me - and you
look OLD!!! Hard livin does that to you quicker than hard work.

And those pictures put to rest any questions about your involvement in
law enforcement.
You were a good look'n kid, gunner.

You will both have to run to catch me!
80 next August. lol

My Dads 83. He married a 47 yr old lady about 8 months ago.

I asked him about sex..he told me if he has to go longer than 30
minutes..then he takes Viagra. She makes him take it about once a
week..the rest of the time she is happy with 30 minutes.

Shrug



--

"
I was once told by a “gun safety” advocate back in the Nineties
that he favored total civilian firearms confiscation.
Only the military and police should have weapons he averred and what did I think about that?

I began to give him a reasoned answer and he
cut me off with an abrupt, “Give me the short answer.”

I thought for a moment and said, “If you try to take our firearms we will kill you.”"

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

John G wrote:

You will both have to run to catch me!
80 next August. lol


They may have to run, but at least they still can. ;-)


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

Michael A. Terrell wrote :
John G wrote:

You will both have to run to catch me!
80 next August. lol


They may have to run, but at least they still can. ;-)

Unfortunatly that is all too true :/

--
John G

John G wrote:

Michael A. Terrell wrote :
John G wrote:

You will both have to run to catch me!
80 next August. lol


They may have to run, but at least they still can. ;-)

Unfortunatly that is all too true :/


I'm in my 60s and can barely walk, most days.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.