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

[tinman]

@Tinman, you do great work, always!!!

in an Incandescent Bulb, Resistance changes with heat - See: Nonlinear Conduction

Any Resistor that changes in Temperature will suffer changes in resistance.

An Incandescent Bulb is not Linear...

   Chris Sykes
       hyiq.org

Yes,the current/voltage curve is non linear,but the only way to dissipate more power from an incandescent bulb is to increase the amount of current flowing through it,and this increase of current will increase the voltage across that globe.

I show the exact opposite,where i decrease the amount of current flowing through the bulb,decrease the voltage across that bulb,but increase the dissipated power across  that bulb.
We are using our CVR to watch this happen,so either the CVR is not telling us the true current flowing through it,or our light bulb has everything back to front--it has to be one of the two,as the current flowing into the system ! MUST! flow through the CVR and bulb first.

Take that inductor away,and what do you think will happen?


Brad

[picowatt]

Tinman,

I watched video two, could not find video one, scanned thru video three.  Some of what I heard in the videos and read in this thread just made me shake my head.

Perhaps it is you that is missing the boat.  Please reread my post and tell me which of the points I raised you disagree with.  I can't believe there is anything I stated in my post that you could possibly disagree with.

Read up on positive and negative temperature coefficient resistors.  Look at the data sheets for various resistors, the temperature coefficient is almost always given (usually stated as ppm/C).   

Measure the cold resistance of a 100 watt incandescent and calculate its power draw based on that resistance.


PW

[picowatt]

Tinman,

Perhaps you should consider building a very simple Wien bridge sine wave oscillator using an incandescent bulb as the gain control element. 

Marvel at how, without even glowing, the varying resistance of the lamp regulates the positive feedback.

Very old school...

PW

[EMJunkie]

Yes,the current/voltage curve is non linear,but the only way to dissipate more power from an incandescent bulb is to increase the amount of current flowing through it,and this increase of current will increase the voltage across that globe.

I show the exact opposite,where i decrease the amount of current flowing through the bulb,decrease the voltage across that bulb,but increase the dissipated power across  that bulb.
We are using our CVR to watch this happen,so either the CVR is not telling us the true current flowing through it,or our light bulb has everything back to front--it has to be one of the two,as the current flowing into the system ! MUST! flow through the CVR and bulb first.

Take that inductor away,and what do you think will happen?


Brad

The Current/Voltage Curve is the Change in the Resistance of the Globe. Because: I = V/R and V = R x I - If R changes, then I and or V must also change because: R = V / I.

Even the CVR will have an amount of Non Linearity to the result.

Current flowing through a Circuit Element is normally proportional to the Applied Voltage across a Circuit Element, not taking into account the Time Domain and the instantaneous measurement in a Non Linear Situation. A Voltage drop Across a Circuit Element, is associated with Heat dissipated from that Circuit Element. Electrical Energy Transformed to Heat. So I am sorry, I don't fully agree.

It is however another good experiment and I may have totally missed something...

   Chris Sykes
       hyiq.org


P.S: The only reason I know this is because I thought I was onto something and this was what it turned out to be.

[picowatt]

From Wiki:

https://en.wikipedia.org/wiki/Incandescent_light_bulb

Current and resistance

The actual resistance of the filament is temperature dependent. The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance when the lamp is operating. For example, a 100-watt, 120-volt lamp has a resistance of 144 ohms when lit, but the cold resistance is much lower (about 9.5 ohms).[50][93]

PW