Thursday, April 4, 2013

Sunrise Lamp Circuit Using MOSFET IRF640

This circuit is a design circuit that can used to make decoration in the house. This circuit is based on LM324 for generate triangle waveform with frequency 700Hz. It is a 120VAC lamp is slowly illuminated over an approximate 20 minute period. This is the figure of the circuit;

The circuit is supplies DC voltage by bridge rectifier to the MOSFET and the 60 Watt. A 6.2K, 5 watt resistor and zener diode is used to drop the voltage to 12 volts DC for the circuit power. The bridge rectifier should be rated at 200 volts and 5 amps or more. In pin 1 LM324 is generate signal and a slow rising voltage is obtained at pin 8. These two signals are compared at pins 12 and 13 to produce a varying duty cycle rectangular waveform at pin 14, which controls the MOSFET and brightness of the 60 watt lamp. When power is applied, the lamp will start to illuminate within a minute or so, and will slowly brighten to full intensity in about 20 minutes.

If you want to adjust this lamp, you can with adjustments to the 270K resistor at pin 9. The 2.2 ohm resistor and .015uF cap connected to the lamp serve to sub press RFI. The diodes at the pin 9 and 10K resistors on pin 8 are used to discharge the 3300uF cap when power is removed. Power should be off for a few minutes before re-starting.

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