RANT CAFFE ASYLUM

[picowatt]

CaptainLoz,

Thanks for replying here.  I enjoy your videos, there has been no drama on my part.  Chris or Chet posted your #7 video which I watched.  I commented that when the POC was driving the two small incandescent lamps the scope was indicating something like 20 watts, which I believed was much more than the two lamps could likely dissipate.  I asked Chris if he knew what lamps you used and if unknown, perhaps he could suggest to you that you try driving the lamps directly from your supply to see what the lamps draw from the supply.

The 14volt at .2 amp is more than I guessed, but even at those numbers, that's 2.8 watts each or 5.6 watts for the two, when driven to full brightness.  At the point in the video where these lamps were the driven load connected to the POC, the scope was indicating 20 watts (if I recall correctly), and the DC supply was putting out something like 17 watts.

So, what we see is 17 watts from the supply being used to light a pair of 2.8 watt lamps (5.6 watts for the pair, if driven to full brightness).  It would be more efficient to drive the lamps directly from the DC supply, requiring only 5.6 watts instead of the 17 watts.

The scope was reading 20 watts or so.  It is very unlikely that many watts were being dissipated by the lamps.  That would be very much above their 5.6 watt rating (for the pair) which would make the lamps either very very bright or damage them.  Because of this I questioned whether or not the scope math was programmed correctly. 

Thanks again,
PW 

Hi Guys,


Some of the comments here are pretty vicious. Just so you know I have been a member here for many years. The reason I joined Chris's forum was because he actually helps you figure stuff out. I am no expert but am learning more and more every day, thanks to Chris and other members. I have been very transparent with all my videos. I have made a lot of mistakes that people point out because I leave the comments on on all my videos. I'm commenting here because Itsu asked me to comment about the bulbs I'm using in my latest experiment.  They're just 14Volt .2A radio shack screw in bulbs. I got them at a clearance sale when they were liquidating. Also a MR16 7.5 watt LED Bulb.  I don't know if the bulbs are consuming all the power shown across the resistor, I just know if you take the measurements as you normally would it's showing a gain.  I am not trying to mislead anyone. I'm just sharing my real time results.  Take it or leave it.


And just to be very clear I am not Chris! That's ridiculous.


If you are interested in my latest experiment follow the thread at aboveunity.com. Or just watch my latest videos, I'm not hiding anything.  Sorry guys, I'm not going to be doing two threads I just don't have the time.


Cheers,
Loz

[picowatt]

CaptainLoz,

Again, consider that in video 7, when the the two incandescent lamps were the only load, the DC supply was delivering around 17 watts.  It was taking 17 watts from the supply to light a pair of 2.8 watt light bulbs (a total of 5.6 watts).  Even if the lamps were overdriven by 100%, making them very bright and shifting their color temperature, they would only draw 11.2 watts.  In the video, the lamps did not look overly bright, or necessarily at full brilliance.  So where is the rest of the power from the supply being wasted?

In video 7, I believe the two lamps were connected in series.  I suggest you try connecting that series string of two lamps directly to the DC supply and adjusting the supply output until the lamps are at a brightness similar to what they were in the video (as driven by the POC).  Compare the wattage required from the supply to light the lamps to the 17 watts used by the circuit in the video. 

PW

[picowatt]

EMJ,

If the circuit were 100% efficient, the two lamps would have been dissipating 3 times their rated power (17 watts from the supply, each lamp dissipating 8.5 watts, the lamps are rated at 2.8 watts).

The lamps would have been very bright and very white.  The lamps did not appear to be overdriven.  They looked closer to their rated output, if even that.

In video 9, CaptainLoz overdrives one of the incandescent lamps, and it is very obvious.

So again, in video 7, when the two incandescent lamps were connected as a load, it was taking 17 watts from the supply to light a pair of 2.8 watt lamps.

PW

[picowatt]

To all,

It was video number 5 I was referring to, not video 7:

https://www.youtube.com/watch?v=Tk9uSOdj-hE

At about 7:30, the load is the two small incandescent lamps.

(Forgive the confusion, EMJ keeps deleting posts...)

The DC supply is providing 14.8 watts (and 2.25 watts for the driver).

At that point in the video, the circuit is using 17 watts from the supply to light a pair of 2.8 watt lamps (5.6 watts total)

Even if the lamps were overdriven 100%, which they do not appear to be, the circuit would still be very inefficient.

If 17 watts is being used to light a pair of 2.8 watt lamps, where is the remainder of the 17 watts being lost?

PW

[bistander]

I butted in on EMJunkie's thread where he was discussing Ohm's Law with member picowatt. He, EMJunkie, of course, deleted my posts along with pw's and his own replies. I had copied my posts along with his reply and parting statement. Here is a paste:

EMJunkie writes:

"25V Pk to Pk at one stage didn't we! So the Globe Rating goes out the window doesn't it!

At: 25 Volts

We get: 25^2 / 70 = 8.92857 Watts, Simple Right!

Now, the Globes are in Parallel, ...
So, again for you, I know its hard, but try, you will get it: RT = 1/R1 + 1/R2"

It is incorrect to use peak to peak voltage in a power calculation like that.

Also, the equation for equivalent resistance of two resistors in parallel is incorrect.

Nice to see you address some of these concerns.
bi

________
Reply:

Bis.....,

25 Volts was given as an example. In some scope shots much higher Pk to Pk were seen!

27 x 0.707 = 19.089

But the waveforms are not purely Sine in shape! So and example was given instead, can you manage to deal with an Example?

I truly look at the Electrical Engineering knowledge here and think you guys are in the dark ages, I know my skills are only average, but wow, its not hard to put you all to shame.

Best wishes, stay safe and well in these Dire Times,
   Chris Sykes

_________

EMJunkie,
Using your attachment, you can see the difference.

1/RT = 1/R1 + 1/R2
vs
RT = 1/R1 + 1/R2

What does a peak to peak voltage times 0.707 represent?

Regards,
bi

_______

By EMJunkie:


P.S: It is clear, 9 of 10 people here, cant figure out the life's most simple things! They are clearly simpletons, and have no idea how V, I and R are related to each other! Even when Thermal Drift is involved! Linear and Non-Linear Conditions. Deliberately Dumb! Its just easier to delete the Idiots!

________

And some people can't copy an equation or do arithmetic.

Regards,
bi