To be deleted

[itsu]

Void,

If you measure the battery voltage with a scope probe and the battery
current with a scope current probe and use your scope math function to compute the average input power,
then that should properly take into account the feedback current from feedback LED, if that is not what you
did previously.

I use both DMM's and the scope to compare, but for calculating power i always use the scope to get consistent measurements over the circuit.
Concerning the use of DMM's, see also the video in a later post.



NP,

Internet is back up, so was able to catch up   



Turbo,

not sure who you are asking, but yes thats a ferrite pot core i use in the transformer.
I don't see to what screenshot you refer with your somewhat oversized    screenshot, could you elaborate?



AG,

not sure to who you are responding, but as my scopeshots show no ringing i guess you are responding to turbo his post.



Itsu

[itsu]

Here the first results of my measurements of the new setup.

Basically i measure at 4 points being across the battery (input) and the 3 power users (2x led and transistor).
I have taken screenshot of those 4 measurement points and put them in below.

The wattage of the transistor is in the 800uW range, so not 800mW as i mention in the video.

A (boring!) video of those 4 measurements can be seen here: https://www.youtube.com/watch?v=7uQ8BBxiU0s

I will repeat these measurements a few times to see if the results stay the same over a period of time.

Regards Itsu

[Void]

Here the first results of my measurements of the new setup.

Basically i measure at 4 points being across the battery (input) and the 3 power users (2x led and transistor).
I have taken screenshot of those 4 measurement points and put them in below.

The wattage of the transistor is in the 800uW range, so not 800mW as i mention in the video.

A (boring!) video of those 4 measurements can be seen here: https://www.youtube.com/watch?v=7uQ8BBxiU0s

I will repeat these measurements a few times to see if the results stay the same over a period of time.

Regards Itsu

Hi Itsu. Nice job! Nice clear presentation. Something does not appear to be adding up in those power measurements
however, but I am not sure off hand why that might be. From your diagram:
Power In: 17.96 mW
Total circuit power consumption: 1.1mW + 770uW + 10.6mW = 12.47mW

I would expect that the total input power and the total circuit power consumption should compare at least fairly close,
but that is not what we have. Either something else in the circuit is consuming a significant amount of power that
is not being measured (I can't think what that might be at the moment), or the power measurements are off in one or
more places for some reason. Can you think of any reason for this discrepency? Unless the coil windings on the ferrite core
are consuming about 5mW? That seems quite high to me, as I wouldn't expect small coils of wire to consume anywhere
near that much power. What do you think?

I think a sanity check test setup of your scope power measurement method to see if the power measurements with
the scope are reasonably correct or not with complex waveforms would be a good idea here.

[Hoppy]

Hi Itsu. Nice job! Nice clear presentation. Something does not appear to be adding up in those power measurements

Pot, caps and Inductor power dissipation.

[itsu]

Hi Void,

Yes, there are some things that don't add up, like the current through the transistor (7.1mA) and below it
the current through the load led (3.7mA) and the current to the 100uF cap / feedback led (5.2mA) being 8.9mA.


Another point i see is the voltage across the transistor and the load led.
If you combine those you get more then what the battery pack (3.75V) delivers:
1.62 + 2.84 = 4.46V
1.72 + 2.89 = 4.61V

When scoping from emitter transistor to cathode load led it shows 3.75V rms again.


So its very hard to get accurate readings, even with my scope setup, especially the current probe needs constant calibration / degausing.

Therefor i am planning to take daily measurements and take the average after some time.

Today i did a second measurement and put the results in a spreadsheet, see below.
There you see that the difference between input and the power users is much smaller (about 1mW)



Itsu