Often times we are asked if it is ok to plug a moving light or an LED fixture into an ETC dimmer. The first preference is always to place these loads on a Relay module. However if a relay module is not currently available, you can use D20/D20E (or D15) dimmable modules, with certain caveats.
No matter what type of dimmer you are using, you must set the dimmer to not regulate the sine wave on the circuit that is providing power to the Fixture. To protect against fluctuating power levels, ETC dimmers regulate the output voltage to a specific level. This affects the sine wave. Most LED and Moving Head fixtures (including those made by ETC) require an un-regulated power source.
Voltage regulation can be changed depending on that dimmer’s Control mode setting in the processor. The “Switched” Control mode will output un-regulated AC voltage when the DMX level is higher than the threshold level. The “Non-dim” Control mode will output regulated AC voltage when the DMX level is higher than the threshold level. (“Switched” mode is not offered on Unison Legacy Racks, SmartPacks, SmartBars, and SmartModules. In these instances, set the mode to “Non-Dim”.) For more information on Regulated sine waves, click here.
The threshold level is the point where the dimmer processor will supply AC voltage. Any DMX level above the threshold will supply AC voltage, and any level below the threshold will not supply AC voltage. In many instances, it can be useful to change the threshold level from its default setting. Keep in mind that changing the threshold from the default 50% is not supported on all devices. You can find more detailed instructions on how to change these settings in your dimming processor User Manual.
Another option is to set a dimmer’s Control mode to “Always-On”. This Control mode is also un-regulated; however, you will be unable to turn off the dimmer from your console. If set to “Always-On”, the only way to turn off the power coming from the dimmer would be to turn off the breaker on the module.
In systems with Sensor3 dimmer racks, TR20SAF or “Thru-Power” modules may be used. This is a module that gives you the capability of a D20, an R20 and a CC20 all built into one unit. For more information on this module, see the third paragraph on this page.
These same options also apply to other loads such as motors, computers and TV’s. The best course is to use a Relay module (R20) or constant current module (CC20), or in Sensor3 systems a Thru-Power Module. However, if you must use a dimmable module, make sure it is set to an un-regulated Control mode.