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Joined: Sep 2005
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Just wondering if someone could help me understand the difference between a low voltage dimmer and an incadescent or line voltage dimmer?
Mike
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Joined: Mar 2001
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I'm not sure about "Low Voltage" dimmers, but I believe the scr-type controller in the dimmer for electronic LV transformers operates in reverse than the typical scr...
Instead of the current being let through at a certain point on the voltage wave (the trigger point) which would cause a bit of a surge, the current comes on at zero and shuts off at a corresponding trigger point. From what I understand, this protects electronic LV dimmers from spikes while allowing the same average, (or RMS?) current flow through the electronics.
Standard dimmers can be used on most magnetic LV transformers.
[This message has been edited by Redsy (edited 10-06-2005).]
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Joined: Dec 2004
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Non-magnetic low voltage transformers are essentially cheap switch-mode power supplies, and rectify the mains into a capacitor, then down convert it at a high frequency.
Trailing edge dimmers are needed to feed these capacitive loads, because the inrush current from a leading edge dimmer would stress the capacitor and rectifiers.
Trailing edge dimmers cannot use an SCR or TRIAC, and have to use a pair of MOSFETs or IGBTs which makes them more expensive.
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Joined: Jul 2005
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"Standard dimmers can be used on most magnetic LV transformers."
If I am not mistaken, when it comes to LV magnetic dimming, the dimmers must be derated by 20% to compensate for loss from transformer IE 600W LV magnetic dimmer is only good for ~450W (9 50W lamps).
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