On Thu, 18 Oct 2018 20:12:55 +0100, (Roger Hayter)
wrote:

Jeff Liebermann wrote:

On Thu, 18 Oct 2018 19:22:02 +0100, (Roger Hayter)
wrote:

Jeff Liebermann wrote:

On Thu, 18 Oct 2018 08:09:01 +0000, Spike
wrote:

On 18/10/2018 01:35, Jeff Liebermann wrote:

diversion into a side-topic snipped

It wasn't a diversion, but if you don't want to discuss it, that's
fine. If you have an allergy or an aversion to numbers, that's also
fine. I'll try not to mention any numbers if you feel threatened.
Fear of numbers (numerophobia or arithmophobia) is amazingly common
these days as we transition from an analog world to a digital world.
Usually, it is fear of some specific number that causes a problem.
However, there are individuals, such as politicians, who fear all
numbers. These might help:
https://www.fearof.net/fear-of-numbe...ia-or-arithmop
hobia/ "How To Overcome Fear Of Numbers"
https://www.youtube.com/watch?v=OKPaeb6nmsw (2:00)

So, how do you make an RF tuning light bulb produce numbers? A light
meter?

By calculation, old boy, by calculation. Don't you do calculations in
the US?

Well, last time I checked, calculations are done using numbers. What
numbers are you using to calculate and how did you conjur them? Do
your light bulbs include a brightness indicator?

You can compare the brightness of two similar lightbulbs with a moderate
amount of precision. You just have to take care that the bulb is not
changing the thing you're measuring too much.

Sure. The standard candle used to measure the distance to a star in
astronomy is such a measurement. The problem is that the standard
candle is great for comparison measurements, it much also be
calibrated against a known illumination source. Finding a light bulb
with a known specific brightness and suitable for making a comparison
does not seem very easy. Same with "similar" light bulbs. One would
still need to calibrate the standard light bulb in some manner. Might
as well use a lux meter.

"Standard candles"
http://www.astro.ex.ac.uk/people/hatchell/rinr/candles.pdf

Note that I'm ignoring the change in filament resistance at different
illumination levels with adds some unwanted non-linearity to the light
bulb power measurement.

You don't have to measure the brightness, you just alter and measure the
DC power to one bulb while comparing it with the RF illuminated one.

Yes, that will work but will provide only a single value of RF power
that corresponds to a single value of brightness. It's also not the
way the "standard candle" works. In the standard candle, there's no
assumption that the brightness of the reference light and the measured
light will be equal. Instead, it relies on inverse square law which
basically states that if you move a light bulb twice as far away, it
will be 1/4th as bright. Move it 3 times as far away, and it's 1/9th
as bright. And so on.

Let's start with an RF powered light at some brightness level. Next
to it, I take a brighter bulb, where I know the brightness. This
light is NOT adjustable and is always the same known brightness. Now,
I move this bulb farther away until it appears to be exactly the same
brightness as the RF powered light bulb. At this point, I know:
1. The distance between the observer (me) and the RF powered light
bulb which I'll call A.
2. The distance between the observer (me) and the reference light
bulb which I'll call B.
3. The brightness of the reference light bulb which I'll call C.
4. I'll call the unknown brightness of the RF powered bulb as D.

Let's say that the observer is 2 meters away from the RF powered
light, and that the reference light is the same brightness as the RF
powered light at a distance of 5 meters. I'll assume the reference
light produced 1000 lux. Therefore, the brightness of the RF powered
light is:
1000 / (5/2)^0.5 = 1000 / 1.58 = 632 lux

Presumably, the reference light was calibrated for brightness at a
given RF level. Let's say it's 50 watts for 1000 lux. Therefore, the
RF power of the RF powered light would be:
632 / 1000 * 50 = 32 watts
Again, notice that I don't need an adjustable reference light, I don't
need a corresponding lux-watts calibration chart, and that there no
inconvenient non-linearities involved due to variations in filament
resistance.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558