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Title: Triac Light Dmmer Sub for Variac? Post by: AJ1G on October 02, 2005, 02:14:52 PM The Variac that I use to regulate the input voltage to a full wave rectifier filter PS that I use to charge the deep cycle batts that run my GRC-19 and ART-13 has crapped out. Was wondering if a SCR dimmer control could be used as a substiture, at least until I either get a mil spec 28V 50A DC supply. or another Variac. Any opinions? My gut feeling is that the SCR dimmer is a bad idea, at least from an RFI standpoint, and have a feeling a transformer/rectifier PS would not be happy being driven by one.
Title: Re: Triac Light Dmmer Sub for Variac? Post by: W1RKW on October 03, 2005, 03:35:14 PM Chris, AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
I don't have a concrete answer for you as I've never tried using a light dimmer to vary AC voltage for anything except on a lightbulb or a soldering iron (purely resistive devices). A light dimmer does chop the AC waveform up and hence the hash one hears in the RF spectrum. I can't imagine the chopped up waveform can be good for the rectifiers in the PS. I would think they'd be "seeing" continuous switching transients. The big question would be is how big would those transients be and if the rectifiers can tolerate them. The transformer might filter some of that junk out but I don't know for sure. Bob |