Gradual On for Lamp I dislike the rude assault you get when you flip on a light switch. Instead of an abrupt on-off switch on a 120 V circuit, I want something that gradually turns on. In other words, you throw a control switch and the resistance in the load's circuit goes from infinity to zero in the span of, let's say, three seconds. The load would be a 500 W incandescent lamp. Is there a commercially available product that could accomplish this? Or is there a simple way to make this circuit?
Google is your friend. (Someone else coined that phrase, but I like it!) http://www.hometech.com/modules/plugin.html Plenty of others like it but that was the first hit. Search for a circuit diagram the same way. Ken
x-10 might do this, but I don't really know. A PIC chip, a TRIAC, and a few other parts could do this job perfectly. There are quite a few examples on the net, just Google 'em up by searching for "PIC" and "dimmer". ;-) You would just need a slight variation on the code to make it do what you wish.
In days of old they used a power NTC thermistor as a surge arrestor in valve TV's to do this. On switchon it has high resisance to limit the initial surge current for all those discharged capacitors and cold valve heater elements. When it heats up it due to the load current it consumes minimum power as the resistance drops right down. It would have to be carefully matched to the load. Whether you can find one the right power for this job, I don't know, but I often wondered why someone didn't coin this potential market. I guess the lamp manufacturers would soon buy them out. Anthony
Start here. http://www.google.com/search?num=10...F-8&oe=UTF-8&q=ramp+dimmer&btnG=Google+Search ....and it's not done with resistance; it's done with duty cycle.
Connect a thermistor in series with the lamp. As the thermistor warms up its resistance goes down and the lamp gets brighter.
I think there are special turn-on (sliding) switches which does what you want to do - it is probably expensive $20 maybe per switch. But churches & some expensive homes use this kind of sliding scale brightness switch. You can slide the switch as fast as you want or as slowly as you want. Side benefit will be that brightness can be controlled precisely (I guess it is really a more elegant dimmer switch - since the SCR or TRIAC controls the pulse width, you will still have 99% efficiency. If you try to do it with resistors, it can become pretty dangerous (failure of circuitry will make the whole circuit glow & you'll be lucky not to burn down your house). Worst thing that a TRIAC or SCR can do is become OPEN (bulb does not turn on at all) or become SHORT (bulb is always on at max. brightness & you lose soft-start & brightness control). Either way, nothing will get hot & definitely no fires are started. I would still buy a professional dimmer switch in metal box just in case the SCR or TRIAC decides to become a flame thrower for a few seconds (some cheap dimmer switches did cause housefires in the past & I am sure there will always be cheap & dangerous products available since 95% of people buy on price only !!!)
