Chinese Lanterns

[Serge Teulon]

Stumbled across this....

 

http://onevillage.org/lighting.htm#glowbal1

 

 

Cheers

[Guy Holt]

For some reason the image of the Current and Voltage Waveforms of a CFL Bulb in the comparison to an incandescent bulb in my explanation of power factor above did not load. Here is that passage again with the image.

 

To understand the power factor of a CFL bulb, and its’ effect on the power supply, it is helpful to compare it to an incandescent bulb. An incandescent light is a simple resistive load. The high resistance of its tungsten filament creates heat until the filament glows - creating light. As we see in the oscilloscope shot below, of a 25W incandescent bulb operating on grid power, the current is always proportional to the voltage (current is represented on the scope as the voltage drop on a 1 Ohm resistor.)

 

Current and Voltage Waveform of a ACEC 25W Incandescent bulb

 

If the applied voltage is sinusoidal, the current generated is also sinusoidal. That is, the current increases proportionately as the voltage increases and decreases proportionately as the voltage decreases. Since the peak of the voltage corresponds to the peak in current, the voltage and current are also in phase and so have a unity power factor (Power Factor of 1.)

 

The voltage and current waveforms below of a CFL bulb operating on grid power is very different from that of the incandescent light above. The most noticeable difference is that the current, generated by the CFL bulb, no longer proportionately follows the nice smooth sinusoidal voltage waveform supplied to it by the power grid. Rather, it has been distorted by electrical components in the ballast of the CFL bulb so that it instead consists of sharp spikes in power that quickly drop off over a short duration. A second distinguishing characteristic is that the peak of the voltage no longer corresponds to the peak in current. The current now “leads” the voltage by 1.7 micro seconds. The voltage and current are no longer in phase as in the case of an incandescent bulb, but instead exhibits what we call a leading power factor.

 

Current and Voltage Waveform of a Brelight 25W CFL Bulb

 

 

The distorted current waveform and leading power factor exhibited here is caused by components in the electronic ballast which use only portions of the voltage waveform, draw current in quick bursts, and then return the unused portions as harmonic currents that stack on top of one another, creating harmonic distortion that pulls the voltage and current out of phase. This creates an opposition to the flow of current that is called capacitive reactance. Where capacitive reactance leads to an inefficient use of power (lots of foam), and the harmonic currents generated can have severe adverse effects on other equipment operating on the same power, it is worth exploring the cause of capacitive reactance and the source of the harmonic currents in more detail.

 

Sorry for the screw up.

 

Guy Holt, Gaffer, ScreenLight & Grip, Boston

[J. Lamar King IMPOSTOR]

I find duvetine cloth too heavy to hang on one side of a lantern without it tipping in that direction.

 

What I like to use is this thin black plastic tablecloth material you can get at any cooking supply store like Smart & Final.

 

What he said, plus you can buy black rip-stop nylon that is light and very durable.

[Guest Mike Andrade]

I painted some china balls recently the same way Chris did. I used Rust-Oleum high heat spray paint. About 5 bucks at Home Depot.

[Chris Burke]

Just plain old cheap flat black spraypaint. This is for about 300W and down, so I can't really comment on how flame retardant the paint is or isn't.

 

 

on the thin paper element, any paint will burn. There probably is a flame retardant one, but with a big enough china ball, you won't have a problem.

[Bruce Taylor]

High heat flat black paint should also be available at just about any auto parts store. It's made for headers/exhaust manifolds and is good to 2000 deg F. Of course the paper will burn long before that!

 

Bruce Taylor

[George Odell]

This is an old post but for what it's worth, I made a reusable Chinese Lantern years ago from a lamp post globe I found at Home Depot. Still use it from time to time. You can see how I did it at this site I created for others to build one.

 

http://www.webtfg.com/make-this-reusable-Chinese-Lantern-page1.html