What'd I do to you? The PCB has rather thin wiring. There's a picture of it in post #12. Though I didn't take a picture of the dimmer, it's in a plastic housing with no room for a heatsink. The ONLY sinking of heat that has been provided is the riveted mount to the "Sink" pin of the dimmer.for that matter to the IGBT he is so in love with.
Overkill is better than underkill. Under do it and I could be revisiting this thread. And the stuff I have is stuff I've had for close to 15 years. Haven't used it for anything else, so what's the harm in using it now? I COULD just throw it away and build the circuit the way you are convinced it should be done. But then what happens if it doesn't hold up? As has been said, the blower (eventually) will run with near no restriction, so the draw will be really close to what I measured. That's a lot of wattage moving through a FET with no heatsink. Yeah, it could be mounted externally, but then I'd be concerned with heat soak. Heat rises in the box and can't be dissipated without a fan or some unknown number (and size of) holes. The IGBT is just as easy to use as it is to disassemble and modify a working dimmer. But should something go wrong - it's likely going to be the Iggy. {edited from iggy to Iggy for Wolframore}
By now it should be clear I don't know as much as some of you long timers. My best experience can be described as a hobbiest and experimenter. I've built logic circuits that have worked - for a while. I've built things that are still working. I've also built things that never worked, and have never been able to figure them out so I abandoned them.
I once built a logic circuit for the car. You start the car, push a button then turn the key off and the engine continues to run. Step on the brake pedal and the circuit shuts off. If the key is not in the ignition and not turned to the run position then you can't steal the car. But if you put the key in the engine is already warm and you can then turn the heater on and have instant heat. But that circuit didn't last very long. So I rebuilt it using diode and relay logic. The circuit worked great. So there have been some accomplishments. Many more failures. And many more opportunities to learn.
Some people like mint ice cream, some don't. Doesn't mean mint ice cream is not good, it's just not the choice of everyone. Using the IGBT is my way of saying I don't care for the idea of modifying the dimmer or risking blowing it up.
Am I "IN LOVE" with the idea? No, not really. But it IS convenient. It gives me a sense of security. Even if it's overkill.
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