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Constant Voltage Transformer Question

T

Tam/WB2TT

Jan 1, 1970
0
Jim Thompson said:
Are they blowing up on turn on or is it when the voltage surges? If its
the former, most likely, why not rig up a dimmer circuit with a shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds giving
the filaments time to warm up a bit.

The RFI-EMI-GUY
[snip]

Good point. You're right, they almost always fail at turn-on.

...Jim Thompson

Jim,

You might want to check your 240V balance. I had a situation here where the
kitchen light got brighter every time the dishwasher turned on.

Tam
 
J

JeffM

Jan 1, 1970
0
Silly thought, but if the load is just incandecents,
why not just use a big thyristor dimmer to (possibly automatically)
trim the RMS value to whatever you happen to like?
Dan Mills

Maybe not silly, but wrong.
A triac-based controller does not control voltage level;
it is a phase controller, varying duty cycle. A triac, once triggered
(assume before 90 degrees and 270 degrees for any brightness at all),
stays triggered until the line voltage crosses zero.
This means that it delivers full peak voltages to the load.
Sorry, Dan. Don't have access to alt.binaries.schematics.electronic.
 
J

Jim Thompson

Jan 1, 1970
0
Jim Thompson said:
Are they blowing up on turn on or is it when the voltage surges? If its
the former, most likely, why not rig up a dimmer circuit with a shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds giving
the filaments time to warm up a bit.

The RFI-EMI-GUY
[snip]

Good point. You're right, they almost always fail at turn-on.

...Jim Thompson

Jim,

You might want to check your 240V balance. I had a situation here where the
kitchen light got brighter every time the dishwasher turned on.

Tam

I had that happen at our old house, the neutral corroded (underground
utilities) and became resistive... some lights brightened, some lights
dimmed, when the furnace blower ran.

...Jim Thompson
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
Jim said:
A major pain-in-the-ass in Arizona is lightbulb lifetime, particularly
this time of year, where one day will require heat and the next not.

So the AC voltage regulation sucks... often popping up to 130VRMS.

Get the power company to fix their regulation. I don't know about AZ,
but in WA, voltage at the point of service is 120 V +/- 5% for a maximum
voltage of 126 at the meter.
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Richard Crowley
Note that film/video people are moving more and more towards
flourescent lighting and there are several vendors now selling
tubes (both traditional and CFL) at color temps of 3000K, 3200K,
5600K, etc. etc. to match industry-standard incandescent sources.
And many of these lamps have color-rendering index (CRI) > 90%.

I don't see how you can have a CRI of 90% with a CT of 3000 K.
 
G

Greg Neff

Jan 1, 1970
0
I read in sci.electronics.design that Greg Neff <greg@guesswhichwordgoes
here.com> wrote (in <[email protected]>) about
'Constant Voltage Transformer Question', on Sat, 1 Jan 2005:




I think you probably mean that 'not all are good', rather than 'all are
no good'.

I think I meant 'All warm-white CFLs that I tried had a very
noticeable difference in colour temperature'

(snip)
AIUI, that's what they think they do.

Hmm. Well then, maybe I am having a CRI problem as well.

(snip)

BTW, I have a question regarding dimming CFLs. One of the effects of
dimming an incandescent lamp is that the colour temperature drops as
the lamp dims. Depending on the application (a romantic dinner for
example) this can be a desired effect. I wonder if this is true for
dimmable CFLs. Has anyone here tried dimmable CFLs, and if so do they
have a pleasant light output when dimmed?

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

Greg Neff
VP Engineering
*Microsym* Computers Inc.
[email protected]
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Greg Neff <greg@guesswhichwordgoes
BTW, I have a question regarding dimming CFLs. One of the effects of
dimming an incandescent lamp is that the colour temperature drops as the
lamp dims. Depending on the application (a romantic dinner for example)
this can be a desired effect. I wonder if this is true for dimmable
CFLs. Has anyone here tried dimmable CFLs, and if so do they have a
pleasant light output when dimmed?

The light comes from the phosphor coating and changes colour very little
with excitation level.

You might have a patent there; a phosphor formulation could be devised
to produce the effect you mention. You'd sell a jillion. (;-)
 
W

Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
Tam/WB2TT said:
Jim Thompson said:
Are they blowing up on turn on or is it when the voltage surges? If its
the former, most likely, why not rig up a dimmer circuit with a shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds giving
the filaments time to warm up a bit.

The RFI-EMI-GUY
[snip]

Good point. You're right, they almost always fail at turn-on.

...Jim Thompson
--
Jim,

You might want to check your 240V balance. I had a situation here where the
kitchen light got brighter every time the dishwasher turned on.

Tam

At work I've found this happens with three phase, and I've seen the
neutral wire carrying substantial current, especially when I measure the
current near areas where there is one or more copiers. They seem to
have a very high current draw at times, when the fuser comes on. I've
seen several volts diff between the neutral and ground. Check to see if
you nave a situation where the neutral and ground are not close to the
same voltage. Run appliances to see if that makes a diff. And if you
find that there is, it can be fixed with some rearrangement of the loads
on the breaker panel.

Back in the '70s a friend got a microwave oven, and I noticed that his
kitchen lights would dim and brighten when the microwave was on. And I
also noticed that at half heat settings, the lights would dim and
brighten at about ten second intervals, which led me to the conclusion
that all the microwave was doing was switching the magnetron on and off,
and not 'dimming' it on a per cycle basis.
 
J

Jim Thompson

Jan 1, 1970
0
On Sun, 2 Jan 2005 08:18:14 -0800, "Watson A.Name - \"Watt Sun, the

[snip]
Back in the '70s a friend got a microwave oven, and I noticed that his
kitchen lights would dim and brighten when the microwave was on. And I
also noticed that at half heat settings, the lights would dim and
brighten at about ten second intervals, which led me to the conclusion
that all the microwave was doing was switching the magnetron on and off,
and not 'dimming' it on a per cycle basis.

AFAIK, that's the way most, if not all, microwaves adjust "power".

...Jim Thompson
 
S

Spehro Pefhany

Jan 1, 1970
0
I read in sci.electronics.design that Greg Neff <greg@guesswhichwordgoes


The light comes from the phosphor coating and changes colour very little
with excitation level.

You might have a patent there; a phosphor formulation could be devised
to produce the effect you mention. You'd sell a jillion. (;-)

http://archive.salon.com/sex/world/2001/01/10/light/


Best regards,
Spehro Pefhany
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Spehro Pefhany <speffSNIP@interlog
DOTyou.knowwhat> wrote (in said:

It's very true that there is nothing new under the sun. But Powergen is
a UK electricity supplier company and I've certainly not seen any sign
of the product being marketed.

Maybe it emitted too much mains harmonic stuff. Or caused flicker. (;-)
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Watson A.Name - "Watt Sun, the
pernews.com>) about 'Constant Voltage Transformer Question', on Sun, 2
Jan 2005:
which led me to the conclusion
that all the microwave was doing was switching the magnetron on and off,
and not 'dimming' it on a per cycle basis.

Yes. I don't think you can phase-control a magnetron. DON'T TRY!
 
Do they make those with floodlight shaping?

I haven't been impressed with the light output of the CFLs I've seen.

I have 5x 75W halogen floods just over the cooking area... 15' up,
that's barely adequate.

...Jim Thompson

I bought some commercial CFL floods, R40 size made by Janmar in Covina
CA. http://www.janmar.com/
The ones I bought are 3 piece. Screw in ballast, plug in 13 Watt
element (available at Home Depot and others) and a screw on R40
reflector

Good points: Good light output, nice color
Bad points: Physically taller than R40 incandescent but within
adjustmant range of the can lamp. Flickers/blinks at startup though it
doesn't 'fade' up. Not dimmable. Not cheap- paid $90 for 2.
Glenn Gundlach
 
T

Tam/WB2TT

Jan 1, 1970
0
Watson A.Name - "Watt Sun said:
.....................................
At work I've found this happens with three phase, and I've seen the
neutral wire carrying substantial current, especially when I measure the
current near areas where there is one or more copiers. They seem to
have a very high current draw at times, when the fuser comes on. I've
seen several volts diff between the neutral and ground. Check to see if
you nave a situation where the neutral and ground are not close to the
same voltage. Run appliances to see if that makes a diff. And if you
find that there is, it can be fixed with some rearrangement of the loads
on the breaker panel.

Power Co fixed it. There was a bad splice in the feed coming off the pole
into the house. You have a point about copiers and printers. I had to run a
separate feed to the color laser printer.

Tam
......................
 
C

Chuck Harris

Jan 1, 1970
0
Jim Thompson wrote:
led me to the conclusion
AFAIK, that's the way most, if not all, microwaves adjust "power".

...Jim Thompson

Back in the early '80s, a company I worked with made a "precision"
microwave that did the power adjustment on a per cycle basis. It was
a simple thing that could go from 10 to 100% power by dropping full
cycles from the transformer's input.

The nice thing about that microwave was it didn't burn small things
when you were running at reduced power. One demonstration they
used was filling a watch glass with saline and running at 10% power
using a conventional microwave, and then the "precision" microwave.
The conventional microwave would spit and spatter as it blew up the
water around the edges of the puddle, the "precision" microwave heated
everything nice and evenly.

-Chuck Harris
 
R

Richard the Dreaded Liberal

Jan 1, 1970
0
I read in sci.electronics.design that Spehro Pefhany <speffSNIP@interlog


It's very true that there is nothing new under the sun. But Powergen is
a UK electricity supplier company and I've certainly not seen any sign
of the product being marketed.

Maybe it emitted too much mains harmonic stuff. Or caused flicker. (;-)

Or, they really _do_ work, and are being withheld from the hoi polloi, so
the lords and ladies get them all to themselves. ;-) Kinda like big oil
suppressing the Pogue carb. ;-)

Cheers!
Rich
 
J

Jim Thompson

Jan 1, 1970
0
Jim Thompson wrote:
led me to the conclusion

Back in the early '80s, a company I worked with made a "precision"
microwave that did the power adjustment on a per cycle basis. It was
a simple thing that could go from 10 to 100% power by dropping full
cycles from the transformer's input.

The nice thing about that microwave was it didn't burn small things
when you were running at reduced power. One demonstration they
used was filling a watch glass with saline and running at 10% power
using a conventional microwave, and then the "precision" microwave.
The conventional microwave would spit and spatter as it blew up the
water around the edges of the puddle, the "precision" microwave heated
everything nice and evenly.

-Chuck Harris

I did a neon light dimmer that way... feed the transformer with full
cycles (to avoid saturation), and switched them in and out as groups
(with TRIACs).

...Jim Thompson
 
R

Rich Grise

Jan 1, 1970
0
I read in sci.electronics.design that Watson A.Name - "Watt Sun, the
pernews.com>) about 'Constant Voltage Transformer Question', on Sun, 2
Jan 2005:

Yes. I don't think you can phase-control a magnetron. DON'T TRY!

I've seen series-modulated magnetrons in military jamming transmitters,
but they have real DC for the plates. The rectifier in the last microwave
oven I took apart was half of a voltage doubler, and the maggie was the
other diode.

Fil. winding
C----| |--+----+UUU+
C C | | |
C D v Fil. If you think I'm going to try to draw
C --- Anode a magnetron, think again. ;-)
C | |
C-----+---+------+
|
GND

I wouldn't even want to try integral-cycle control with a klooge like
that!

Cheers!
Rich
 
J

Jeff

Jan 1, 1970
0
Jim Thompson said:
That's where the ceiling is ;-) (They're recessed PAR3 floods.)

Have you considered low voltage Halogen's? They used to come with a linear
transformer, to drive the halogen bulb at 12V. Common wattages were/are 20
and 50W. Newer ones use a SMPS with a crude unrectified output. Power
density of such SMPS is extremely high. We have a under cabinet low voltage
halogen system, which uses 3 x 20W bulbs, all run off of a single SMPS
that's about 1" x 3/4" x 2", including the standard size replaceable fuse!
Most of these newer low voltage halogens with the SMPS should last much
longer, since the SMPS should give a regulated output, and the filaments in
the halogen bulbs are much heavier for a given wattage.




John, at least here in Canada/US, fluoro tubes are rated for 40W, for a
standard 4' tube. Energy saver tubes, which seem to be the only ones that
are commonly available now are rated for 34W, which fit the same fixture
without modification. The 34W tubes are junk, since the seem to only give
out 1/2 the light. New, T8 fluorescent tubes are rated for 32W, and are
significantly brighter then the older 40W tubes, they are also much
skinnier, with a diameter of about 1".
 
J

Jim Thompson

Jan 1, 1970
0
[snip]
Have you considered low voltage Halogen's? They used to come with a linear
transformer, to drive the halogen bulb at 12V. Common wattages were/are 20
and 50W. Newer ones use a SMPS with a crude unrectified output. Power
density of such SMPS is extremely high. We have a under cabinet low voltage
halogen system, which uses 3 x 20W bulbs, all run off of a single SMPS
that's about 1" x 3/4" x 2", including the standard size replaceable fuse!
Most of these newer low voltage halogens with the SMPS should last much
longer, since the SMPS should give a regulated output, and the filaments in
the halogen bulbs are much heavier for a given wattage.
[snip]

Helluva good idea! Maybe automotive headlamps? They're quite rugged.

...Jim Thompson
 

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