I. RC4 Series 3 Harmonized Design devices of all families (RC4Magic, RC4Magic-900, LumenDim, and W-DIM) support two different PWM frequencies and multiple dimmer curvesDimmer curvesAn instrument’s  dimming curve is simply how bright the light is in relation to the level of the associated DMX channel. A good dimmer should be perceived by your eye to be smooth and linear: if you set a light level of 50%, the lamp should appear to be half as bright as it does at 100%. […]
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II. The linear dimmer curve will always be running at 77Hz

A. This is a very low frequency for high-power conventional lamps (usually halogen bulbs)

II . ONLY the ISL dimmer curves (the ISL slow curveISL slow curveLEDs do not dim linearly: when dimmed to a linear 50%, they appear only slightly less bright than at 100%.  The level must drop to 25% to appear at half brightness.  To make LEDs appear linear, they must be controlled with the Inverse Square Law curve.  All good quality LED dimmers use this technique.  RC4 […]
Read more » , the ISL fast curveISL fast curveLEDs do not dim linearly: when dimmed to a linear 50%, they appear only slightly less bright than at 100%.  The level must drop to 25% to appear at half brightness.  To make LEDs appear linear, they must be controlled with the Inverse Square Law curve.  All good quality LED dimmers use this technique.  RC4 […]
Read more », and inverted forms of these) will use PWM frequencies

A.  When the Linear curve is selected, changing the PWM frequencyPWM frequencyTo see a visual representation and in-depth explanation of PWM, watch our latest video This chart is also a helpful resource. PWM stands for Pulse-Width Modulation.  It is a method for using a switching device (one that can only be on or off) to create what appears to be analog changes in level.  This is done by […]
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Only LEDs are a fast enough light source for PWM frequency to matter, and LEDs should be used with the ISL dimmer curve.  This is why higher frequencies are only available for the ISL curve.