gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
230429-1706 EDT
Experiment performed with utility nominal 120 V 60 Hz supply.
The load was two bulbs, a 9.35 W CREE made in China with my date code of 160902-3-4, and a 7.5 W 120 V tungsten filament unit, in parallel. A series resistor was used to change voltage simultaneously to the two parallel bulbs with a relay contact shorting the resistor. This way there was no change in voltage other other other than between the two selected states.
The two times of the cycle were adjustable, but the long time was left at 3 seconds, and the other half cycle was set to either 0.12 second or 2 seconds. My eye ball was the visual indicator.
Using calculated current for each test, 16.85 W we get 0.14 A. . Then 0.14 A times my series resistors gives a good correlation on measured voltage drop. For 22 ohms this is 3.08 V. I measured 3.3 V. For 47 ohms this is 6.58 V, and I measured 6.6 V.
Visually I could barely detect the light change from a 3 V change, and it was harder to see it on the CREE.
Visually the almost 7 V change was only a little more detectable on the CREE, but slightly more noticeable on the incandescent.
Others should doheir own experiments and report back.
.
Experiment performed with utility nominal 120 V 60 Hz supply.
The load was two bulbs, a 9.35 W CREE made in China with my date code of 160902-3-4, and a 7.5 W 120 V tungsten filament unit, in parallel. A series resistor was used to change voltage simultaneously to the two parallel bulbs with a relay contact shorting the resistor. This way there was no change in voltage other other other than between the two selected states.
The two times of the cycle were adjustable, but the long time was left at 3 seconds, and the other half cycle was set to either 0.12 second or 2 seconds. My eye ball was the visual indicator.
Using calculated current for each test, 16.85 W we get 0.14 A. . Then 0.14 A times my series resistors gives a good correlation on measured voltage drop. For 22 ohms this is 3.08 V. I measured 3.3 V. For 47 ohms this is 6.58 V, and I measured 6.6 V.
Visually I could barely detect the light change from a 3 V change, and it was harder to see it on the CREE.
Visually the almost 7 V change was only a little more detectable on the CREE, but slightly more noticeable on the incandescent.
Others should doheir own experiments and report back.
.
