RSSDIY Tube lamp 1.1
Posted by Phillip Torrone |
Apr 30, 2006 04:22 PM
DIY Projects, Electronics |
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I just finished up one of these today (see Mad Scientists Light in the blog).
It's working great and and like the blog I am using a 40watt tube bulbs.
Not being an experienced MAKEr yet I am wondering about how to control the max voltage into the lighting array.
I can turn the dimmer up all the way and the lights get pretty bright but it totally ruins the effect. What do I need to put in the circuit before the dimmer to drop the power down so that when the dimmer is maxed out it's still only getting enough power for the eerie glow?
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nice.. ive finished mine. my design only used 2 bulbs though to save money.. also im going to look for a vintage "high voltage" plaque to go on the front of mine ..
other stuff ive thought about is: have the dimming controlled by the amount of light in the room.. or pulsating along with the beat of music.. (i got this idea from someones headlights dimming with the power being drawn from his subwoofer.. )
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To get the lights down quite a bit, you can wire them in series...this won't give a low glow at the dimmer's max setting unless you've got a lot of bulbs, but you'll be able to dial it way down. Of course, then you have the old-fashioned-christmas-light problem...if one has a problem, the whole array goes dark.
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To lower the maximum brightness of the dimmer you could try putting a resister in series with the potentiometer and the capacitor that's attached to the gate leg of the triac. You'll have to experiment to find the correct value. A downside to this approach is that the larger the value of the resister, the worse the initial hysteresis when you turn on the lamp (that is, you'll have to turn it to "max" to make the bulb light, then down to "min" to get it to the brightness you want).
I've seen a few home brew dimmer designs that use a bridge rectifier so that the firing capacitor can correctly synchronize with the zero crossing of the AC wave despite having a low initial charging current. One such design is here and the approach is explained in greater detail here.
Standard disclaimers apply about working with line level voltages, plus one because IANAEE (I am not an electrical engineer).
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