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Author Topic: Accurate Measurements on pulsed system's harder than you think.  (Read 83350 times)

digitalindustry

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #45 on: December 11, 2015, 03:47:11 AM »

In this thread,only those that can ! show ! what they say to be true will be taken notice of. So your first task is to show Quote: Incandescent bulbs tend to regulate the current flowing thru them.  As more voltage is applied to the bulb and it attempts to draw more current, the temperature of the filament increases, which increases the filaments resistance, which reduces the current flowing thru it.
So i would like you to show us how you can increase the voltage across an incandescent bulb,while maintaining or decreasing the current flowing through it. Show us how you can dissipate more power from an incandescent bulb with less current flowing through it,and dissipate less power with more current flowing through it-->as i have shown.

I have shown the effect in the form of experiment's,and presented those experiments and results by way of video. In this thread,those that choose to argue the point will do so with actual experiments-->(! not text book physics !),and will present there experiment right here on this thread. No credibility will be given here to words without experimental  data to back up there claims.
Words are no longer good enough.

~~~~~


Brad

I agree with this, I want to learn this effect, PW should demonstrate this effect in an experiment as TK did his, otherwise there is a definite credibility gap, as we can say that the effect has been reproduced as TM describes.

after discovering that Pi is not only 'incorrect' but it's also essentially a very inefficient way to calculate (i.e how much human methods seem) i'm sure some people that understand or learned this might be starting to question the reality in which they live?

I'd like to see a simple experiment where:

- an incandescent bulb of this type shines brighter with less or the same current.

note:

(even though bizarrely the last video showed two different currents along the same direct path.)
(however TK experiment reproduced the effect without the CVR did it not? ) (i.e wound R)

ah i'm staring to see the light here the CVR is on the negative, the inductor is the key, of course electrons don't exist, and so called 'electron flow' if this is looked at as a closed magnetic flux system it starts to make more sense.

EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #46 on: December 11, 2015, 04:15:12 AM »
Hmmm.... I think some people are still missing some points and being distracted by Red Herrings.

1. The current measured by monitoring the voltage drop across the CVR is also the current flowing through the bulb. The elements are in strict series so the same current is flowing through them both. Right?

2. The brightness of the bulb is an indication of the power being dissipated in the bulb. A dimmer bulb means less power dissipated in the bulb, a brighter bulb means more power dissipated in the bulb. This is true regardless of factors like the temperature coefficient of resistance of the bulb, and the duty cycle of pulsation.  Right?

3. The instantaneous power being dissipated in the bulb is Watts=I2R, where I is the current at the instant of measurement and R is the bulb's resistance at that instant. Right? And this is also equivalent to Watts=V2/R, so solving for R we have R=V/I by Ohm's Law. Right?


4. When the capacitor is connected, the current through the bulb is (relatively) constant, so there is no difficulty with the "mean" value of the current. So the power dissipated in the bulb is also constant. The resistance of the bulb can be calculated by R=V/I. We know I from the CVR measurement, but what is V?
Question: Does the voltage drop across the bulb as measured by the scope give us the "V" value for this equation when the voltage is constant, duty cycle 100 percent?

5. When the capacitor is _not_ connected, the current through the bulb is pulsed. So the power being supplied to the bulb is no longer constant. Depending on the thermal lag of the filament, this power is "smeared out" or averaged over some time interval, so the bulb is actually dissipating some power even when the filament is not receiving any current. Hence it can appear to be glowing steadily even though its current supply is pulsed. During the current peaks, as measured by the scope, the power dissipated is related to the _square_ of the current, adjusted somehow for the thermal lag and the temperature coefficient of resistance of the filament. Right?
Question: Is it legitimate to use the simple "mean" value of the current to calculate the average power dissipated by the bulb in this case, since the power supplied during the peaks is related to the square of the current?



Are the Red Herrings starting to jump out of the bucket yet?


A Circuit to study might be a good start:

Tinman, is this Circuit correct? SW1 being the manual Clip lead connection.

   Chris Sykes
       hyiq.org

Lets figure out what's going on...

EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #47 on: December 11, 2015, 04:32:33 AM »


First thing I noticed is that the Wave Forms are completely different, no sign of any Pulsing:

   Chris Sykes
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EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #48 on: December 11, 2015, 04:50:57 AM »
I think if the Circuit is right, and the Scope Shots are an indication, we can see there is a lot less Voltage on the Yellow Trace especially... The Frequency, Rise/Fall time, there, will change the Lights Luminosity.

The total Applied Voltage across the Globe is very much different.

   Chris Sykes
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EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #49 on: December 11, 2015, 05:05:59 AM »
Something is wrong with the mean calculation!

At 2 volts per division for the Yellow Trace, its not giving you the right figure.

I agree with what Verpies said:

Yes, incandescent bulbs are not linear but that does not mean that they are not monotonic.
Light bulb's brightness depends on the current flowing through it and Tinman is correct that more current always means more brightness....and in his experiment this is all that matters.

I am more concerned how his scopes calculates the average of these pulses, e.g. from the screen data, from memory or from the waveform period...


   Chris Sykes
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JOKE: Try DC Coupling.... Hahahaha

EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #50 on: December 11, 2015, 05:31:07 AM »
Compared to:

RMS = Vpeak * 1/sqrt(2) = 8 * 0.707 = 5.6568V

NOTE: The above Calculation is supposed to be only good for Symmetrical Sine Waves. I realise its not totally correct to use it here. This is just to give some idea of the difference.

Correction: Pk to Pk , not Peak:

RMS = Vpeak to peak * 1/sqrt(2) = 8 * 0.35355 = 2.8284V

The Globe is seeing a Difference of 8 Volts at a frequency of 68.4 Hz.

   Chris Sykes
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tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #51 on: December 11, 2015, 05:58:36 AM »
Verpies & TK

It is good to see some understand as to what it is we are looking at here.

PW
I in no way disagree with what you say about the resistance increasing across the bulb when.the temperature rises on the filament.  What I am saying is the the current flowing through that bulb must increase in order for there to be a temperature rise which causes the rise in resistance.

I am showing a reduction of current flowing through that bulb, but an increase in light and heat output, which means the bulb is dissipating more power. Remember, the voltage also drops across the bulb when the current flowing through it drops-but the dissipated power in the form of heat and light increases.-as TK has also shown, and he is using what you would class as an acceptable CVR.


EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #52 on: December 11, 2015, 06:14:49 AM »
Verpies & TK

It is good to see some understand as to what it is we are looking at here.

PW
I in no way disagree with what you say about the resistance increasing across the bulb when.the temperature rises on the filament.  What I am saying is the the current flowing through that bulb must increase in order for there to be a temperature rise which causes the rise in resistance.

I am showing a reduction of current flowing through that bulb, but an increase in light and heat output, which means the bulb is dissipating more power. Remember, the voltage also drops across the bulb when the current flowing through it drops-but the dissipated power in the form of heat and light increases.-as TK has also shown, and he is using what you would class as an acceptable CVR.



Yep, I must admit, took me a bit to get it... Little bit of study required.


   Chris Sykes
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EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #53 on: December 11, 2015, 06:35:52 AM »


Tinman - Can you scope C2 in run mode and post pic please?

   Chris Sykes
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EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #54 on: December 11, 2015, 06:57:54 AM »
On connection of C2 via the Clip Lead (SW1 in the Circuit) this adds a large Capacitive reactance to the Circuit. Its hard to get any data from the screenshots of the scope in the video because the Cap Smooth's out the Pulsing very well!!!

But, this should introduce a Current Lead into the Circuit. Hard to see without more info. This could also be part of the cause of the Higher current seen.

All be it very small as we see mostly DC.

   Chris Sykes
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EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #55 on: December 11, 2015, 07:04:03 AM »


Yep, I must admit, took me a bit to get it... Little bit of study required.


   Chris Sykes
       hyiq.org



I really don't see anything out of the norm here now I get it. PW what do you think?

I think accurate Input Measurements could be obtained from "Cap Connected - mean value is wrong" Image, as long as the readings are fixed. Channel 1's Mean Value does not appear to be correct: 3.36 Volts

Channel 2's Mean Value of 144mv does appear to be pretty good.

   Chris Sykes
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EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #56 on: December 11, 2015, 07:37:44 AM »
Before C2 is connected:

After Q1 switched the Negative side of the Coil to Ground, we will see a Voltage drop across all four components:

1: 1 Ohm Resistor
2: Globe
3: Coil
4: Q1's internal Resistance.

Totaling the Total Battery Voltage. Series Resistance is approximately: R = 126 Ohms. Using Ohms law you can calculate the Power: R x I2 = 1.26 watts approximately.

Introducing C2  (6800uf Capacitor), via SW1, after the Globe (LA1) ensures that the grounding of the above two components:

1: 1 Ohm Resistor
2: Globe

through Components:

3: Coil
4: Q1's internal Resistance.

only occurs after the Capacitor C2 (6800uf Capacitor), charge is below the Voltage Drop of the Coil and Q1, or completely empty of Charge, which will never happen. As a result we see no more Pulsed Waveform, the power through these components is the total power being delivered to C2 (6800uf Capacitor) less the losses of these components.

Series Resistance of Components 3 and 4 is: R = 90 Ohms. The Potential Voltage difference across the 1 Ohm Resistor and the Globe when SW1 is closed is only around 1.844 Volts. Using Ohms law you can calculate the Power: R x I2 = 1.76 watts approximately.

Sorry Brad, but this is the way I see it.

   Chris Sykes
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« Last Edit: December 11, 2015, 10:50:49 AM by EMJunkie »

TinselKoala

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #57 on: December 11, 2015, 09:57:17 AM »


I really don't see anything out of the norm here now I get it. PW what do you think?

I think accurate Input Measurements could be obtained from "Cap Connected - mean value is wrong" Image, as long as the readings are fixed. Channel 1's Mean Value does not appear to be correct: 3.36 Volts

Channel 2's Mean Value of 144mv does appear to be pretty good.

   Chris Sykes
       hyiq.org

There are probably spikes that aren't being resolved at that timebase setting. A faster timebase might show these spikes. I think the "mean" calculation in TinMan's shot could be thrown off by these spikes for some reason.

My scope seems to be giving near-correct values for "Average" in spite of the spikes.

My scope does have some baseline offset though; I probably need to run the Self-Cal routine again since the temperature has dropped in here. The readings of the circuit under power should be adjusted for these offsets, probably.

First shot below: baseline offset with no power to my circuit.
Second shot below: traces with power applied, no capacitor.
Third shot below: traces with capacitor connected. You can barely see the spikes at this horizontal timebase.
Fourth shot below: the spikes with cap connected, at a faster timebase.

EMJunkie

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #58 on: December 11, 2015, 10:20:25 AM »
There are probably spikes that aren't being resolved at that timebase setting. A faster timebase might show these spikes. I think the "mean" calculation in TinMan's shot could be thrown off by these spikes for some reason.

My scope seems to be giving near-correct values for "Average" in spite of the spikes.

My scope does have some baseline offset though; I probably need to run the Self-Cal routine again since the temperature has dropped in here. The readings of the circuit under power should be adjusted for these offsets, probably.

First shot below: baseline offset with no power to my circuit.
Second shot below: traces with power applied, no capacitor.
Third shot below: traces with capacitor connected. You can barely see the spikes at this horizontal timebase.
Fourth shot below: the spikes with cap connected, at a faster timebase.


Thanks TK,

Can your scope do the math on the spikes? Would be interesting to know what the math is on them.

EDIT: Dur sorry ignore me, was looking for the Math Window...

   Chris Sykes
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tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #59 on: December 11, 2015, 10:30:56 AM »
Before C2 is connected:



Totaling the Total Battery Voltage. Series Resistance is approximately: R = 126 Ohms. Using Ohms law you can calculate the Power: R x I2 = 1.26 watts approximately.

Introducing C2  (6800uf Capacitor), via SW1, after the Globe (LA1) ensures that the grounding of the above two components:

1: 1 Ohm Resistor
2: Globe

through Components:

3: Coil
4: Q1's internal Resistance.

only occurs after the Capacitor C2 (6800uf Capacitor), charge is below the Voltage Drop of the Coil and Q1, or completely empty of Charge, which will never happen. As a result we see no more Pulsed Waveform, the power through these components is the total power being delivered to C2 (6800uf Capacitor) less the losses of these components.

Series Resistance of Components 3 and 4 is: R = 90 Ohms. The Potential Voltage difference across the 1 Ohm Resistor and the Globe when SW1 is closed is only around 1.844 Volts. R x I2 = 1.76 watts approximately.

Sorry brad, but this is the way I see it.

   Chris Sykes
       hyiq.org

Then you are seeing things all wrong EMJ.

Quote
After Q1 switched the Negative side of the Coil to Ground, we will see a Voltage drop across all four components:

1: 1 Ohm Resistor
2: Globe
3: Coil
4: Q1's internal Resistance.

No you wont,you will see a voltage across all four components when Q1 switches on,as there is no voltage across any when the circuit is open except Q1. As you can see in both mine and TK's scope shot's,there is no voltage across the CVR or bulb when Q1 is open,and the cap disconnected. We are looking at the CVR and the bulb,and that is where the scope probe's are placed.

I ask the same of you that i have asked of others that think there is nothing to it-->post a video without the inductor,and show us how an incandescent bulb can dissipate more power with less total current flowing through it,and less power with more total current flowing through it.

You may also like to look at TK's latest scope shot's,and have a look at the total current flowing through the CVR,and voltage across the bulb with and without the cap connected in the circuit. Are you telling me that the error margin could be this big ?. And dont forget,this is TK carrying out these test,and he knows his way around power measurements.


Brad