[BlindHandyMan] How Dimmer Switches Work
The New and Improved Way Instead of diverting energy from the light bulb into a resistor, modern resistors rapidly shut the light circuit off and on to reduce the total amount of energy flowing through the circuit. The light bulb circuit is switched off many times every second. The switching cycle is built around the fluctuation of household alternating current (AC). AC current has varying voltage polarity -- in an undulating sine wave, it fluctuates from a positive voltage to a negative voltage. To put it another way, the moving charge that makes up AC current is constantly changing direction. In the United States, it goes through one cycle (moving one way, then the other) 60 times a second. The diagram below shows this sixtieth-of-a-second cycle. Picture (Metafile) A modern dimmer switch chops up the sine wave. It automatically shuts the light bulb circuit off every time the current reverses direction -- that is, whenever there is zero voltage running through the circuit. This happens twice per cycle, or 120 times a second. It turns the light circuit back on when the voltage climbs back up to a certain level. Picture (Metafile) This turn-on value is based on the position of the dimmer switch's knob or slider. If the dimmer is turned to a brighter setting, it will switch on very quickly after cutting off. The circuit is turned on for most of the cycle, so it supplies more energy per second to the light bulb. If the dimmer is set for lower light, it will wait until later in the cycle to turn back on. That's the basic concept, but how does the dimmer actually do all of this? In the next couple of sections, we'll look at the simple circuitry that makes it work. In the last section, we saw that a dimmer switch rapidly turns a light circuit on and off to reduce the energy flowing to a light switch. The central element in this switching circuit is a triode alternating current switch, or triac. A triac is a small semiconductor http://www.howstuffworks.com/diode.htm device, similar to a diode or transistor. Like a transistor, a triac is made up of different layers of semiconductor material. This includes N-type material, which has many free electrons, and P-type material, which has many holes where free electrons can go. For an explanation of these materials, check out How http://www.howstuffworks.com/diode.htm Semiconductors Work. And, for a demonstration of how these materials work in a simple transistor, see How Amplifiers Work http://www.howstuffworks.com/amplifier.htm . Here's how the N-type and P-type material is arranged in a triac. Picture (Metafile) You can see that the triac has two terminals, which are wired into two ends of the circuit. There is always a voltage difference between the two terminals, but it changes with the fluctuation of the alternating current. That is, when current moves one way, the top terminal is positively charged while the bottom terminal is negatively charged, and when the current moves the other way the top terminal is negatively charged while the bottom terminal is positively charged. The gate is also wired into the circuit, by way of a variable resistor. This variable resistor works the same basic way as the variable resistor in the old dimmer switch design, but it doesn't waste nearly as much energy generating heat. You can see how the variable resistor fits into the circuit in the diagram below. Picture (Metafile) So what's going here? In a nutshell: * The triac acts as a voltage-driven switch. * The voltage on the gate controls the switching action. * The variable resistor controls the voltage on the gate. The Circuit When there is normal voltage across the terminals and little voltage on the gate, the triac will act as an open switch -- it won't conduct electricity. This is because the electrons from the N-type material fill in holes along the border with the P-type material, creating depletion zones, insulated areas where there are few free electrons or holes (see this page http://www.howstuffworks.com/led1.htm for a full explanation of depletion zones). If you apply a strong enough voltage to the gate, it will disrupt the depletion zones so electrons can move across the triac. The exact sequence varies depending on the direction of the current -- that is, which part of the AC cycle you're in. Let's say the current is flowing so the top terminal is negatively charged and bottom terminal is positively charged. The circuit is arranged so that the voltage boost on the gate will have the same charge as the top terminal. So we get something that looks like this: Picture (Metafile) When the gate is charged, the voltage difference between the gate and the lower terminal is strong enough to get electrons moving between them. Moving electrons out of the N-type material -- area e -- disrupts the depletion zone between areas e and d. Introducing more free electrons into area d disrupts the
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[BlindHandyMan] washing machine
HI, Just wondering if the guy that had the washing machine problem got it fix?? Just happen I have a machine that is doing same thing.. So I would interested how he came out... ROB FROM MINNESOTA [Non-text portions of this message have been removed]
Re: [BlindHandyMan] washing machine
Hi Rob and list, Just so happened I have been very busy and haven't had time to report but I got it fixed today. A friend came over and looked in the tub and found a screw that fell out of my jeans pocket and got lodged in a whole in the bottom of the tup ware water is suppose to drain and it locked the entire thing up. It was so berried, I don't think I would ever have found it. All the taking apart I did was for nothing but I had a lovely time putting it all back together and I washed a load and it works fine now. Now I know more about the innerds of my washing machine than I ever thought I would have. grins I tell you, I have never enjoyed washing clothes as much as I have tonight, ever before in my life! smile It is true, you don't know what you've got till it's gone. HTH At 10:05 PM 4/8/2009, you wrote: HI, Just wondering if the guy that had the washing machine problem got it fix?? Just happen I have a machine that is doing same thing.. So I would interested how he came out... ROB FROM MINNESOTA [Non-text portions of this message have been removed] __ Information from ESET Smart Security, version of virus signature database 3975 (20090330) __ The message was checked by ESET Smart Security. http://www.eset.comhttp://www.eset.com
[BlindHandyMan] victory washing machine woes!
Hi list, I sent this to a list member, but, I wanted to also reply to the list to let all you good folks that helped me know my saga is now resolved. Thanks for all the input. It is saved for future use. I have been very busy and haven't had time to report but I got my washing machine fixed today. A friend came over and looked in the tub and found a screw that fell out of my jeans pocket and got lodged in a whole in the bottom of the tup ware water is suppose to drain and it locked the entire thing up. It was so berried, I don't think I would ever have found it. All the taking apart I did was for nothing but I had a lovely time putting it all back together and I washed a load and it works fine now. Now I know more about the innerds of my washing machine than I ever thought I would have. grins I tell you, I have never enjoyed washing clothes as much as I have tonight, ever before in my life! smile It is true, you don't know what you've got till it's gone. Again, thanks to all of you who helped me with ideas with this problem. Kevin
Re: [BlindHandyMan] victory washing machine woes!
I still reckon it was a fugitive wire from one of your bras! What do the rest of you think? - Original Message - From: Kevin Doucet To: blindhandyman@yahoogroups.com Sent: Thursday, April 09, 2009 12:11 AM Subject: [BlindHandyMan] victory washing machine woes! Hi list, I sent this to a list member, but, I wanted to also reply to the list to let all you good folks that helped me know my saga is now resolved. Thanks for all the input. It is saved for future use. I have been very busy and haven't had time to report but I got my washing machine fixed today. A friend came over and looked in the tub and found a screw that fell out of my jeans pocket and got lodged in a whole in the bottom of the tup ware water is suppose to drain and it locked the entire thing up. It was so berried, I don't think I would ever have found it. All the taking apart I did was for nothing but I had a lovely time putting it all back together and I washed a load and it works fine now. Now I know more about the innerds of my washing machine than I ever thought I would have. grins I tell you, I have never enjoyed washing clothes as much as I have tonight, ever before in my life! smile It is true, you don't know what you've got till it's gone. Again, thanks to all of you who helped me with ideas with this problem. Kevin [Non-text portions of this message have been removed]
