How to make a non dim channel

hi there

can anyone tell me how to create a non dim channel on the ETC Express? i need to control a fan machine. i have only real dimmers in the theatre and would like to use them as switch.

thanks a lot!


  • hi felix.
    you need to be aware, that a dimmer will never output a perfect sine wave, even if you set it to non-dim in the console. yes, you will avoid the ugliest parts (in between 0 and 100), but neither will 0 be real 0, nor will 100 be a real 100...
  • This brings up a very interesting point. Do the Sensor dimmer modules, when set to non-dim actually control true on off power for those sine wave led fixtures to be turned off or do they need to be relay modules instead?
  • For most models of Sensor dimmer, the electronics and inductor are still in the circuit when set to non-dim in the rack so the waveform is altered and voltage and current are out of phase. Relay modules or ThruPower modules in relay mode are recommended.
  • Felix;

    Depending on the components in your system,  and how your fan is connected or powered, there are several ways to accomplish this.

    At the Console:

    If the fan is going to be always on:

    Park the dimmer. Parked dimmers, stay at their parked level as long as the console has power. Blackout and grandmaster do not effect parked dimmers.

    [Stage], [S6], [Dim],[Dimmer #], [At], [Full].

    If you the fan needs to be at full but you want to turn it on and off through the show:

    In the patch screen set the dimmer profile to be full at 1%. This way whenever the channel is above 0, the console outputs 100.

    [Patch],[S7],[Dimmer #], [S6], [6], [Enter].

    If you have a Relay or thru-Power module setting available, that is your best solution because ; as others have mentioned, if you are drawing power through an SCR based dimmer (like in a Sensor or Unison Rack), the choke and SCR (Silicon Control Rectifier), are always in line and will make some modifications to the wave form. Depending on your fan this may cause it to run a bit "weird".  However if all you have are standard dimming modules. there are solutions.

    We have created different modes you can put your dimmers into. The two that would suit your best are either Non Dim or Switched.

    These two modes both provide "constant" power to the dimmers output, but the key difference between them is how that power is regulated.

    Non Dim Mode

    A dimmer set to Non-Dim still regulates the power in that the SCR switches open and closed at the zero cross point in the power waveform. For some devices this causes no ill effects, for others  ( like fans and motors), this can cause some stress and may effect operational speeds.

    Switched Mode

    A dimmer set in switched mode sends unregulated power by keeping the SCR open all the time. It is as close as you are going to get to bypassing the SCR entirely. If you have to use a dimmer to power a fan or motor in my experience, I  would recommend using switched mode. It is not perfect, but it usually works.  

    Both modes are settable on a dimmer by dimmer basis and have a threshold setting which determines their DMX switch point between on and off. The default switch point is 50%.

    Regardless or which you choose,. the choke is still going to effect rise time so your start from off may take longer than when plugged into wall power.

    Setting this whole thing up

    I always advice making changes to firing modes and output as close to the device as possible. This way no matter what your control source, the output is as you need it. However in your case I would both set the dimmer to switched at the rack and set the dimmer profile to full at 1% in the console. This way you don't have to remember to set your channel above the 50% switching threshold.

    I hope this helps. If you do not have Unison or Sensor dimmers, let me know what type of dimmers you have. Most modern systems allow you to set this type of firing mode.



    The default threshold is 50%, meaning that from 50%-100% the dimmer is on and between 0-49% it is off. You can leave this setting as is and make sure you set the level of park in your console accordingly.

  • Thank you. I heard this recently and wanted to get some addtl info. A school I am helping out remodel after a fire has a 24 channel Sensor dimmer rack and they plan on using the dimmer rack channels for some of their led power up on the bars because that is the only thing wired to the bars (various dimmer channels spread over the venue). Originally I just thought putting those few modules on non-dim would be ok however since I heard this info that will change. Don't know what led's they are planning on getting yet but I wanted to give them the heads up.