T
Tom Biasi
Guest
On 11/20/2012 1:43 AM, Jasen Betts wrote:
Tom
reminding Michael his was about a 1/2 sine wave at 50%.
Tom
D
David Eather
Guest
On Tue, 20 Nov 2012 11:14:04 +1000, Michael A. Terrell
<mike.terrell@earthlink.net> wrote:
<mike.terrell@earthlink.net> wrote:
Not at all true. Every waveform has an RMS value.Tom Biasi wrote:
On 11/19/2012 7:31 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 4:43 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 1:05 PM, Michael A. Terrell wrote:
krw@att.bizzz wrote:
On Mon, 19 Nov 2012 09:29:51 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
Jasen Betts wrote:
On 2012-11-18, default <default> wrote:
Your power line voltage is given as a nominal value. 120
volts could
mean anything from 105 to 126, your resistor has to be able
to keep
the leds happy in that range, with some derating for
temperature too,
if you plan to encounter some high ambient temps.
A capacitor makes a lot of sense to drop the voltage with
minimal
power loss. And then you still need some resistance for when
the cap
is discharged and hit with a instantaneous voltage of ~150
peak.
I usually also include a diac or zener to limit fast voltage
spikes, a
cap across the DC output might serve the same purpose.
I have a night light using a full wave bridge to power the
leds. A .5
uf / 200 VAC cap in series with the AC input to the fwb along
with a
100 ohm 1/4 watt series resistor. A diac across the 3 white
leds
limits voltage spikes. I accidentally shorted a cap when I
was
experimenting with it - all three leds shorted, the resistor
opened,
and it happened so fast I didn't see much of anything -
didn't even
singe the paint on the carbon film resistor.
it may have been a fusible resistor, using one of them lets
them use a
cheaper capacitor, like an ordinary 250V polyester
120 VAC is 339.36 Volts, peak to peak.
But unless you're putting it across 240V (both legs) it'll never
see
more than half that. -ish.
I was just pointing out that in some circuits you can have
that
across a capacitor in a 120 VAC circuit. I had an argument with
someone
on another newsgroup who claimed he could use a single 1N34 diode
in a
tube radio to rectify the AC line. He also refused to beleive
that a
1n4007 used in a series filament string wouldn't drop the
effective
voltage to 84.84 V minus the forward voltage drop. He a a couple
dozen
others insisted that it would drop to an effective voltage of 60
volts.
0.318 x Vmax of the input sinusoidal waveform or 0.45 x Vrms of the
input sinusoidal waveform.
One half of the AC waveform = 50% power, not 50% voltage into a
resistive load so it's equal to 70.7% * VAC, minus the diode drop.
Choose your own math.
Show that I'm wrong. There were series sting TV sets built with a
"Dropping Diode". 120 VAC supply and 84 volt string of filaments. It
took a little calculation to see what was happening. The bad thing
was
that the half wave AC played hell with the CRT filament. I modified
them by adding a separate filament transformer for the CRT.
I see what you are saying. But don't forget that RMS only applies to a
sine wave not 1/2 of a sine wave.
I just showed you what your "couple dozen others" were using.
Wire it up and see.
I've seen it 'wired up' in lots of variations. Also, I didn't say it
was RMS, I sad it was the 'Effective Voltage'. RMS can't apply to
anything except a 100% pure sine wave?
M
Michael A. Terrell
Guest
David Eather wrote:
Yes, including ones with a DC offset. You missed the smiley.
On Tue, 20 Nov 2012 11:14:04 +1000, Michael A. Terrell
mike.terrell@earthlink.net> wrote:
Tom Biasi wrote:
On 11/19/2012 7:31 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 4:43 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 1:05 PM, Michael A. Terrell wrote:
krw@att.bizzz wrote:
On Mon, 19 Nov 2012 09:29:51 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
Jasen Betts wrote:
On 2012-11-18, default <default> wrote:
Your power line voltage is given as a nominal value. 120
volts could
mean anything from 105 to 126, your resistor has to be able
to keep
the leds happy in that range, with some derating for
temperature too,
if you plan to encounter some high ambient temps.
A capacitor makes a lot of sense to drop the voltage with
minimal
power loss. And then you still need some resistance for when
the cap
is discharged and hit with a instantaneous voltage of ~150
peak.
I usually also include a diac or zener to limit fast voltage
spikes, a
cap across the DC output might serve the same purpose.
I have a night light using a full wave bridge to power the
leds. A .5
uf / 200 VAC cap in series with the AC input to the fwb along
with a
100 ohm 1/4 watt series resistor. A diac across the 3 white
leds
limits voltage spikes. I accidentally shorted a cap when I
was
experimenting with it - all three leds shorted, the resistor
opened,
and it happened so fast I didn't see much of anything -
didn't even
singe the paint on the carbon film resistor.
it may have been a fusible resistor, using one of them lets
them use a
cheaper capacitor, like an ordinary 250V polyester
120 VAC is 339.36 Volts, peak to peak.
But unless you're putting it across 240V (both legs) it'll never
see
more than half that. -ish.
I was just pointing out that in some circuits you can have
that
across a capacitor in a 120 VAC circuit. I had an argument with
someone
on another newsgroup who claimed he could use a single 1N34 diode
in a
tube radio to rectify the AC line. He also refused to beleive
that a
1n4007 used in a series filament string wouldn't drop the
effective
voltage to 84.84 V minus the forward voltage drop. He a a couple
dozen
others insisted that it would drop to an effective voltage of 60
volts.
0.318 x Vmax of the input sinusoidal waveform or 0.45 x Vrms of the
input sinusoidal waveform.
One half of the AC waveform = 50% power, not 50% voltage into a
resistive load so it's equal to 70.7% * VAC, minus the diode drop.
Choose your own math.
Show that I'm wrong. There were series sting TV sets built with a
"Dropping Diode". 120 VAC supply and 84 volt string of filaments. It
took a little calculation to see what was happening. The bad thing
was
that the half wave AC played hell with the CRT filament. I modified
them by adding a separate filament transformer for the CRT.
I see what you are saying. But don't forget that RMS only applies to a
sine wave not 1/2 of a sine wave.
I just showed you what your "couple dozen others" were using.
Wire it up and see.
I've seen it 'wired up' in lots of variations. Also, I didn't say it
was RMS, I sad it was the 'Effective Voltage'. RMS can't apply to
anything except a 100% pure sine wave?
Not at all true. Every waveform has an RMS value.
Yes, including ones with a DC offset. You missed the smiley.
M
Michael A. Terrell
Guest
Tom Biasi wrote:
50% power, which requires reducng the input to 70.7%. Mutiply
70.7%(I) * 70.7%(E) and you get 49.49%(P)
50% power, which requires reducng the input to 70.7%. Mutiply
70.7%(I) * 70.7%(E) and you get 49.49%(P)
T
Tom Biasi
Guest
On 11/20/2012 11:28 AM, Michael A. Terrell wrote:
Tom
Wire it up and measure it with a true RMS meter.
Tom
M
Michael A. Terrell
Guest
Tom Biasi wrote:
I have. I have four working Fluke 8050A meters. I also have a
'Sensitive Research' brand bolometer type true RMS meter.
I have. I have four working Fluke 8050A meters. I also have a
'Sensitive Research' brand bolometer type true RMS meter.
T
Tom Biasi
Guest
On 11/20/2012 3:27 PM, Michael A. Terrell wrote:
M
Michael A. Terrell
Guest
Tom Biasi wrote:
Exactly what I've been saying all along. 50% of the power of a full
sine wave delivered into a resistive load. I saw that 30 years ago.
You remove 50% of each complete cycle, and you remove 50% of the power.
Exactly what I've been saying all along. 50% of the power of a full
sine wave delivered into a resistive load. I saw that 30 years ago.
You remove 50% of each complete cycle, and you remove 50% of the power.
T
Tom Biasi
Guest
On 11/20/2012 6:00 PM, Michael A. Terrell wrote:
get about 60-65 volts.
Have fun.
Tom
I have used a diode in series with tube filaments for 50 years. I always
get about 60-65 volts.
Have fun.
Tom
M
Michael A. Terrell
Guest
Tom Biasi wrote:
Then you are doing something wrong, like running it on 85 to 92
volts, or using a diode with a very high forward drop.
Then you are doing something wrong, like running it on 85 to 92
volts, or using a diode with a very high forward drop.
T
Tom Biasi
Guest
On 11/20/2012 8:25 PM, Michael A. Terrell wrote:
across the diode.
M
Michael A. Terrell
Guest
Tom Biasi wrote:
Bullshit. You said you've been doing it for 50 years. What True RMS
Voltmeter did you have 50 years ago? You really need to study how the
diode works.
Bullshit. You said you've been doing it for 50 years. What True RMS
Voltmeter did you have 50 years ago? You really need to study how the
diode works.
T
Tom Biasi
Guest
On 11/21/2012 7:57 AM, Michael A. Terrell wrote:
Have a nice Thanksgiving.
D
David Eather
Guest
On Wed, 21 Nov 2012 23:21:10 +1000, David Eather <eather@tpg.com.au> wrote:
On Wed, 21 Nov 2012 02:25:46 +1000, Michael A. Terrell
mike.terrell@earthlink.net> wrote:
David Eather wrote:
On Tue, 20 Nov 2012 11:14:04 +1000, Michael A. Terrell
mike.terrell@earthlink.net> wrote:
Tom Biasi wrote:
On 11/19/2012 7:31 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 4:43 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 1:05 PM, Michael A. Terrell wrote:
krw@att.bizzz wrote:
On Mon, 19 Nov 2012 09:29:51 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
Jasen Betts wrote:
On 2012-11-18, default <default> wrote:
Your power line voltage is given as a nominal value. 120
volts could
mean anything from 105 to 126, your resistor has to be
able
to keep
the leds happy in that range, with some derating for
temperature too,
if you plan to encounter some high ambient temps.
A capacitor makes a lot of sense to drop the voltage with
minimal
power loss. And then you still need some resistance for
when
the cap
is discharged and hit with a instantaneous voltage of ~150
peak.
I usually also include a diac or zener to limit fast
voltage
spikes, a
cap across the DC output might serve the same purpose.
I have a night light using a full wave bridge to power the
leds. A .5
uf / 200 VAC cap in series with the AC input to the fwb
along
with a
100 ohm 1/4 watt series resistor. A diac across the 3
white
leds
limits voltage spikes. I accidentally shorted a cap when
I
was
experimenting with it - all three leds shorted, the
resistor
opened,
and it happened so fast I didn't see much of anything -
didn't even
singe the paint on the carbon film resistor.
it may have been a fusible resistor, using one of them lets
them use a
cheaper capacitor, like an ordinary 250V polyester
120 VAC is 339.36 Volts, peak to peak.
But unless you're putting it across 240V (both legs) it'll
never
see
more than half that. -ish.
I was just pointing out that in some circuits you can
have
that
across a capacitor in a 120 VAC circuit. I had an argument
with
someone
on another newsgroup who claimed he could use a single 1N34
diode
in a
tube radio to rectify the AC line. He also refused to beleive
that a
1n4007 used in a series filament string wouldn't drop the
effective
voltage to 84.84 V minus the forward voltage drop. He a a
couple
dozen
others insisted that it would drop to an effective voltage of
60
volts.
0.318 x Vmax of the input sinusoidal waveform or 0.45 x Vrms
of the
input sinusoidal waveform.
One half of the AC waveform = 50% power, not 50% voltage
into a
resistive load so it's equal to 70.7% * VAC, minus the diode
drop.
Choose your own math.
Show that I'm wrong. There were series sting TV sets built
with a
"Dropping Diode". 120 VAC supply and 84 volt string of
filaments. It
took a little calculation to see what was happening. The bad
thing
was
that the half wave AC played hell with the CRT filament. I
modified
them by adding a separate filament transformer for the CRT.
I see what you are saying. But don't forget that RMS only applies
to a
sine wave not 1/2 of a sine wave.
I just showed you what your "couple dozen others" were using.
Wire it up and see.
I've seen it 'wired up' in lots of variations. Also, I didn't
say it
was RMS, I sad it was the 'Effective Voltage'. RMS can't apply to
anything except a 100% pure sine wave?
Not at all true. Every waveform has an RMS value.
Yes, including ones with a DC offset. You missed the smiley.
Ah. When I read it I was surprised at the name/mistake. My funny bone
needs tweaking.
M
Michael A. Terrell
Guest
David Eather wrote:
I do that in an attempt to get people to look at what the thread
contains, rather than just posting nonsense. Sometimes it works.
On Wed, 21 Nov 2012 23:21:10 +1000, David Eather <eather@tpg.com.au> wrote:
On Wed, 21 Nov 2012 02:25:46 +1000, Michael A. Terrell
mike.terrell@earthlink.net> wrote:
David Eather wrote:
On Tue, 20 Nov 2012 11:14:04 +1000, Michael A. Terrell
mike.terrell@earthlink.net> wrote:
Tom Biasi wrote:
On 11/19/2012 7:31 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 4:43 PM, Michael A. Terrell wrote:
Tom Biasi wrote:
On 11/19/2012 1:05 PM, Michael A. Terrell wrote:
krw@att.bizzz wrote:
On Mon, 19 Nov 2012 09:29:51 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
Jasen Betts wrote:
On 2012-11-18, default <default> wrote:
Your power line voltage is given as a nominal value. 120
volts could
mean anything from 105 to 126, your resistor has to be
able
to keep
the leds happy in that range, with some derating for
temperature too,
if you plan to encounter some high ambient temps.
A capacitor makes a lot of sense to drop the voltage with
minimal
power loss. And then you still need some resistance for
when
the cap
is discharged and hit with a instantaneous voltage of ~150
peak.
I usually also include a diac or zener to limit fast
voltage
spikes, a
cap across the DC output might serve the same purpose.
I have a night light using a full wave bridge to power the
leds. A .5
uf / 200 VAC cap in series with the AC input to the fwb
along
with a
100 ohm 1/4 watt series resistor. A diac across the 3
white
leds
limits voltage spikes. I accidentally shorted a cap when
I
was
experimenting with it - all three leds shorted, the
resistor
opened,
and it happened so fast I didn't see much of anything -
didn't even
singe the paint on the carbon film resistor.
it may have been a fusible resistor, using one of them lets
them use a
cheaper capacitor, like an ordinary 250V polyester
120 VAC is 339.36 Volts, peak to peak.
But unless you're putting it across 240V (both legs) it'll
never
see
more than half that. -ish.
I was just pointing out that in some circuits you can
have
that
across a capacitor in a 120 VAC circuit. I had an argument
with
someone
on another newsgroup who claimed he could use a single 1N34
diode
in a
tube radio to rectify the AC line. He also refused to beleive
that a
1n4007 used in a series filament string wouldn't drop the
effective
voltage to 84.84 V minus the forward voltage drop. He a a
couple
dozen
others insisted that it would drop to an effective voltage of
60
volts.
0.318 x Vmax of the input sinusoidal waveform or 0.45 x Vrms
of the
input sinusoidal waveform.
One half of the AC waveform = 50% power, not 50% voltage
into a
resistive load so it's equal to 70.7% * VAC, minus the diode
drop.
Choose your own math.
Show that I'm wrong. There were series sting TV sets built
with a
"Dropping Diode". 120 VAC supply and 84 volt string of
filaments. It
took a little calculation to see what was happening. The bad
thing
was
that the half wave AC played hell with the CRT filament. I
modified
them by adding a separate filament transformer for the CRT.
I see what you are saying. But don't forget that RMS only applies
to a
sine wave not 1/2 of a sine wave.
I just showed you what your "couple dozen others" were using.
Wire it up and see.
I've seen it 'wired up' in lots of variations. Also, I didn't
say it
was RMS, I sad it was the 'Effective Voltage'. RMS can't apply to
anything except a 100% pure sine wave?
Not at all true. Every waveform has an RMS value.
Yes, including ones with a DC offset. You missed the smiley.
Ah. When I read it I was surprised at the name/mistake. My funny bone
needs tweaking.
I do that in an attempt to get people to look at what the thread
contains, rather than just posting nonsense. Sometimes it works.
M
Michael A. Terrell
Guest
Tom Biasi wrote:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
You too, but I'm done wth you. I gave you the math & the foremulas,
but you continue posting in ignorance and I have better things to do
with my little remaining time.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
You too, but I'm done wth you. I gave you the math & the foremulas,
but you continue posting in ignorance and I have better things to do
with my little remaining time.
T
Tom Biasi
Guest
On 11/21/2012 12:27 PM, Michael A. Terrell wrote:
I respect that you are done with me so I'll just answer your question.
Back then I worked for Ballantine Labs in Boonton, NJ. There were
several true RMS voltmeters at my disposal.
When applying your math and formulas one must consider we are not
working with AC anymore but unfiltered (or pulsating) DC. The peak is at
at a 50% duty cycle so the filaments would be subjected to that DC value
which would be Vpeak/pi. By your own admission several dozen others
tried to explain this to you.
I bid you well.
Tom
I hope you had a nice thanksgiving.
I respect that you are done with me so I'll just answer your question.
Back then I worked for Ballantine Labs in Boonton, NJ. There were
several true RMS voltmeters at my disposal.
When applying your math and formulas one must consider we are not
working with AC anymore but unfiltered (or pulsating) DC. The peak is at
at a 50% duty cycle so the filaments would be subjected to that DC value
which would be Vpeak/pi. By your own admission several dozen others
tried to explain this to you.
I bid you well.
Tom
P
P E Schoen
Guest
"Tom Biasi" wrote in message news:50afd828$0$9830$607ed4bc@cv.net...
show a low limit of 2 Hz and says nothing of DC:
http://www.ballantinelabs.com/323meter.htm
The older Model 320 only goes as low as 15 Hz and the manual specifically
states that it DOES NOT include any DC component. Thus you would need to
measure the true-RMS AC and then add the DC component using sqrt(AC^2+DC^2).
http://www.tubebooks.org/file_downloads/ballantine_320_true_rms.pdf
Apparently you did not work as a design engineer at Ballantine. Even a
technician should know the basics of true-RMS voltage measurement. Read my
previous post for more details.
Paul
Were the true-RMS voltmeters AC coupled? The specs of the Ballantine 323
show a low limit of 2 Hz and says nothing of DC:
http://www.ballantinelabs.com/323meter.htm
The older Model 320 only goes as low as 15 Hz and the manual specifically
states that it DOES NOT include any DC component. Thus you would need to
measure the true-RMS AC and then add the DC component using sqrt(AC^2+DC^2).
http://www.tubebooks.org/file_downloads/ballantine_320_true_rms.pdf
Apparently you did not work as a design engineer at Ballantine. Even a
technician should know the basics of true-RMS voltage measurement. Read my
previous post for more details.
Paul
T
Tom Biasi
Guest
On 11/23/2012 11:13 PM, P E Schoen wrote:
Michael used the 1/2 power to calculate what voltage would produce it,
but the voltage would be sine-wave AC not 1/2 rectified DC.
It's totally irrelevant to what was being discussed.
Michael used the 1/2 power to calculate what voltage would produce it,
but the voltage would be sine-wave AC not 1/2 rectified DC.
P
P E Schoen
Guest
"Tom Biasi" wrote in message news:50b0d8a2$0$24755$607ed4bc@cv.net...
either polarity DC, or any combination thereof. A proper true-RMS meter will
read any of them as the equivalent heating effect. However, components other
than ideal resistors are affected by the harmonic content, duty cycle, peak
voltages, and crest factor. Taken to extremes, there will be a measurable
difference because of the effects of time, although the total amount of heat
generated will be the same.
Since you mentioned the Ballantine meters it would be assumed that they were
what you used for your measurements as you posted previously for a half-wave
rectified voltage. The fact that they are capacitively coupled is highly
relevant.
Paul
It matters not if the waveform is sinusoidal, square, half-wave rectified,
either polarity DC, or any combination thereof. A proper true-RMS meter will
read any of them as the equivalent heating effect. However, components other
than ideal resistors are affected by the harmonic content, duty cycle, peak
voltages, and crest factor. Taken to extremes, there will be a measurable
difference because of the effects of time, although the total amount of heat
generated will be the same.
Since you mentioned the Ballantine meters it would be assumed that they were
what you used for your measurements as you posted previously for a half-wave
rectified voltage. The fact that they are capacitively coupled is highly
relevant.
Paul