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Lamp brightening over 30min

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yogibear

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Hey all

Im building a circuit that turns on an 80W bulb over 30min. Im plannin on running the bulb through a triac which runs from a 220v ac source. I plan to control the triac using a 10V rectified circuit, where a cap charges over 30min.Im new at triacs so i want to know if/what its turn on voltage is, and if i can simply apply my rising voltage to the gate of the triac to cause the bulb to brighten?
 
Thanks. Do you by any chance have any suggestions on how this can be done, or where i can find more info on it?
 
Hey all

Im building a circuit that turns on an 80W bulb over 30min. Im plannin on running the bulb through a triac which runs from a 220v ac source. I plan to control the triac using a 10V rectified circuit, where a cap charges over 30min.Im new at triacs so i want to know if/what its turn on voltage is, and if i can simply apply my rising voltage to the gate of the triac to cause the bulb to brighten?
Well it is not quite that easy...

Start with a basic triac circuit set to say 90% brightness:

https://www.electro-tech-online.com/custompdfs/2008/09/2001JUN14_AMD_AN5PDF.pdf

Then put PWM a FET through a resistor to the timing cap. With a little trial and error you should be able to get a fair amount of control on it.

Barring that you would need a micro to do all the timing...

It would be easier to put a PWM FET inside a diode bridge to do it.
 
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First you need a zero crossing detetector circuit. Use every 0-detection point as reference for phase control.Use a microprocessor to increase phase angle from zero to 90deg within the desired time - stepping 0.05deg/sec for a 30minute period.

With the output of the MCU you can control a triac which will respond accordingly.

Boncuk
 
hi yogi,
I would agree with Boncuk, except the firing angle from 0 thru 180deg from zero to full lamp intensity.


Can you say why you are doing this, just curious.:)
 
As i said... it is much easier to just put a PWM FET in a bridge than it is to jump through hoops to create TRIAC timing
 
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