Stamp dimming control of 110VAC
tractionfan
Posts: 4
I want to control 110VAC lamp dimming by firing a Triac at varying points in the AC half cycle. I was wondering about the SSR's ability to work at that speed. I also would need a way to detect the zero-crossing point so I could "count" an approriate delay before firing... all within the half-cycle of the 60hz AC line.
But... maybe I don't really need to do that considering the long lag reaction time of filament bulbs. Rather I could just provide some on-off output with varying degrees of on and off but with a cycle much greater than the 120 hz of 1/2 cycle AC.
Any thought from anyone?
But... maybe I don't really need to do that considering the long lag reaction time of filament bulbs. Rather I could just provide some on-off output with varying degrees of on and off but with a cycle much greater than the 120 hz of 1/2 cycle AC.
Any thought from anyone?
Comments
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax
Dallas Office
I had been looking at SSRs which seem to come with or without zero-cross but I interpreted that to refer to how they operated.· Didn't see any referenced zero cross output.
By the way, it would seem that running the dimming on an AC lamp would be a natural for a STAMP, but I haven't seen any application notes or projects about it.
By the way, my application is for "sun light" in a diorama.· I have been using a Vellerman Kit which provides nice adjustable slow on slow off, but that kit is no longer available.· I have a number of dioramas (connected) and was thinking of controlling each diorama's "sun" with a stamp, and then controlling the start timing from a master stamp.· Result: Sun setting in the East, and rising in the West.
A MOC3032, available from Jameco, is an optically-coupled, zero-crossing "triac" (actually it's an 'SBS'.)· You can use it directly for applications requiring little current.· For anything considerable (more than that required for a neon bulb), you'll have to use it to trigger a "real" Triac.
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=113953
The H11A is an optically-coupled AC-input photo-transistor.· The H11L2 is an optically-coupled microprocessor-compatible schmitt trigger.
09/29/05 Addendum:
· You can't dim a light with a solid-state relay, because it works like a relay (i.e., its output is on or it's off.)· SSRs don't have a linear region, they don't have the ability to change the conduction angle by varying the voltage to the control input (the IRED·in the opto-coupler section isn't varying the gate voltage.)
· There are SSRs with zero-crossing outputs.·
· Unlike a relay,·an SSR's·"output" doesn't open like a switch, it's more like a leaky switch (when it's "off" you will measure your 120vac on the load side.)
Post Edited (PJ Allen) : 9/29/2005 4:41:41 PM GMT
Chris I