# Dimmer Switches **URL:** \ **Category:** Everything Else\ **Created:** [July 18, 2013, 1:17am UTC](https://forum.psaudio.com/t/dimmer-switches/296 "2013-07-18T01:17:02Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Frode](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@Frode](https://forum.psaudio.com/u/Frode)\ **Post date:** [July 19, 2013, 9:04am UTC](https://forum.psaudio.com/t/dimmer-switches/296/21 "2013-07-19T09:04:28Z")
> Part of the issue is what dimmer you use. I use a dimmer in the main sound room without any issue whatsoever. It works because of the dimmer I use which is a higher end Lutron that says it is "quiet". Indeed, all dimmers work by chopping the waveform but the better ones have a reasonably large filter inside that reduces the harmonics to almost nothing. Yes, but if it is constructed correctly they should come with a 'zero-crossing chip' meaning that the switching is done when the AC feed is zero (i.e. 60 times a second). ---
**Author:** ![wglenn](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/wglenn/32/172_2.png) [@wglenn](https://forum.psaudio.com/u/wglenn)\ **Post date:** [July 19, 2013, 9:12am UTC](https://forum.psaudio.com/t/dimmer-switches/296/22 "2013-07-19T09:12:39Z")
> frode said: 'zero-crossing chip' Hmmm. Wonder if these are available in the USA? ---
**Author:** ![Elk](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/elk/32/1240_2.png) [@Elk](https://forum.psaudio.com/u/Elk)\ **Post date:** [July 19, 2013, 9:35am UTC](https://forum.psaudio.com/t/dimmer-switches/296/23 "2013-07-19T09:35:35Z")
> Gordon said: http://www.ee.teihal.gr/labs/electronics/web/downloads/Light\_dimmer\_circuits.pdf This is quite an article. Interesting. For those interested, it addresses why dimmers make noise and the ways to address this in the design of the dimmer. ---
**Author:** ![Elk](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/elk/32/1240_2.png) [@Elk](https://forum.psaudio.com/u/Elk)\ **Post date:** [July 19, 2013, 9:37am UTC](https://forum.psaudio.com/t/dimmer-switches/296/24 "2013-07-19T09:37:22Z")
> frode said: . . . the switching is done when the AC feed is zero All dimmers switch at the zero crossing; this is how they work. :) ---
**Author:** ![mariankiely](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@mariankiely](https://forum.psaudio.com/u/mariankiely)\ **Post date:** [July 19, 2013, 9:40am UTC](https://forum.psaudio.com/t/dimmer-switches/296/25 "2013-07-19T09:40:39Z")
Yup. In between the As and the Cs This is the “cause” of the problems. ---
**Author:** ![Frode](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@Frode](https://forum.psaudio.com/u/Frode)\ **Post date:** [July 19, 2013, 12:30pm UTC](https://forum.psaudio.com/t/dimmer-switches/296/26 "2013-07-19T12:30:01Z")
> > frode said: . . . the switching is done when the AC feed is zero > > > All dimmers switch at the zero crossing; this is how they work. :) In 2013 I have to agree to this. Here is one circuit: http://pdf.datasheetcatalog.com/datasheet/motorola/MOC3042.pdf What confuses me is that it seems that it is a non-zero crossing principle that is used in dimmers (random phase triac controller). If it switches under load, then noise is inevitable. ---
**Author:** ![Elk](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/elk/32/1240_2.png) [@Elk](https://forum.psaudio.com/u/Elk)\ **Post date:** [July 19, 2013, 12:42pm UTC](https://forum.psaudio.com/t/dimmer-switches/296/27 "2013-07-19T12:42:36Z")
I believe you are correct. I did some reading and found that a random phase triac controller does not detect zero crossing and can remain on as the phase changes. This would create more noise than zero crossing. Thanks for bringing this up - neat stuff. [Previous page](https://forum.psaudio.com/t/dimmer-switches/296.md?page=1)