Accurate Measurements on pulsed system's harder than you think.

[EMJunkie]

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
       hyiq.org

[EMJunkie]

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
       hyiq.org

[TinselKoala]

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]

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
       hyiq.org

[tinman]

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.

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