LED bulbs work on current control, not voltage. The small power supply that comes with the Jansjos takes the incoming voltage, rectifies it to DC, then uses that DC to force a current through the LED bulb. The current level through the bulb is regulated, ie regardless of the incoming voltage (over a very wide range) the supply provides a constant current so you don't see any flickering or variation in intensity if the utility voltage varies. Almost all the inexpensive dimmers vary the average voltage using a pulse waveform created by a silicon controlled rectifier. This method won't do anything to the LED power supply unless the pulse width is so narrow the regulators stop working, and at that point the supply current will collapse and the LED will go dark. Sometimes you'll see a flickering when this happens. There is no external way to adjust the intensity on the Jansjos. You may be able to modify the power supply but that would take some effort and understanding of how the thing works.
Based on my experience with diffusers, if you are going to build one it's a golden opportunity to adjust the size and shape the resulting source to maximize photographic qualities, ie rather than simply making a diffuser, make a director.
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