Replies

1. 
   gdcarpenter | May 15, 2007 01:41am | #1

   I'm no electrician, but my basic understanding is that the solid state units 'clip' the wave. In that sense they are much more energy efficient than standard resistor speed controls that just 'burn' the energy not going to the bulb by heating up the resistor. I'm sure someone will expound better than me.

   Let's not confuse the issue with facts!

2. 
   DanH | May 15, 2007 03:07am | #2

   Practically all modern motor speed controls are solid state. (Well, technically even rheostat speed controls are "solid state", but we won't get into that.)

   An electronic speed control works pretty much the same as an electronic lamp dimmer -- the power is only switched on for part of each cycle. The motor controls just include additional logic to keep themselves from self-destructing due to the reactive voltage produced when the current is switched off, plus logic to reduce the motor heating caused by the high-frequency components in the switched signal.

   I've never examined any in detail, but is suspect that the additional components are mainly a couple of extra diodes and choke coils, and maybe a slightly "smarter" IC in the heart of things.

   In higher power units there will be different speed controls for induction vs commutated motors, but for stuff under about a half horse the same control would work for both (though the "curve" may be more satisfactory for one vs the other). And special provisions (ie, a burst of full power) may need to be made for starting the motors, especially induction motors.

   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
3. 
   rasconc | May 15, 2007 04:01am | #3

   Couldn't explain but the ones I have had the best luck with were the ones with distinct speeds rather than the variable slide ones.  Our church ahd some fans and they hummed rather loud when in anything less than high.  Got some that had off-low-med-high-max and they are great.

1. 
   etherhuffer | May 15, 2007 05:43am | #4

   Got a brand on those? I really like the electronic 60/30/20/10 push button countdown timers. But for the fans I just need to slow them down. http://www.etherhuffer.typepad.com

1. 
   rasconc | May 15, 2007 07:05am | #7

   I want to say Lutron but I looked online and did not see it, could have been Leviton, I will try to remember and look next time.

4. 
   barmil | May 15, 2007 06:16am | #5

   I have a Fantech exhaust fan in my bathroom, and it's either on or off. Why would you wish to control its speed? I don't understand. You're not the green guy with the Juno shower, are you?

1. 
   etherhuffer | May 15, 2007 07:02am | #6

   Hehehehehe. NO! I overfanned the space a bit and its a little louder than I would prefer. The roof fan the same. http://www.etherhuffer.typepad.com