PWM Halogen Lamp Dimmer

  • Rajkumar Sharma
  • moderate
  • Tested


High Current PWM Halogen Dimmer controller project is designed around SG3525 IC and High current MOSFET.  Project can handle lamp up to 5 Amps (10Amps Possible with big heat sink) and supply 12-24V DC .Ideal for Halogen Dichroic Lamp or Halogen Lamp.


  • Supply input 15 to 24 VDC
  •  Load-Lamp 12 to 24 VDC @ 5 Amps (10amps possible with big heat sink on Mosfet)
  •  Onboard preset for frequency adjust
  •  Frequency adjustable 4 KHz to 30 KHz
  •  PWM Duty cycle 0 to 100% (+/- 5%)
  •  Potentiometer for dimming adjust
  •  Soft Start facility
  •  Clamp diode for protection
  •  Power-On LED indicator
  •  Compact design and high quality
  •  Lamp and supply connection via screw terminal connector
  •  Four mounting holes of 3.2 mm each
  •  PCB dimensions 56 mm x 42 mm




Parts List



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IRFP250 is not the best choice for switching 12v (24V) resistive load because of its 90mR on resistance. Also the switching frequency is rather high for PWMing low voltage halogen lap. Some 100Hz is sufficient because of the high thermal mass of the filament and it will reduce switching losses in the MOSFET. Because of the thermal mass, the soft-start function seems to be of little use too.
The idea of grounding both outputs and taking the MOSFET driving voltage from the supply of both totem poles seems rather novel to me. I still do not know if I like it or not 🙂 Nevertheless, a simple 555 timer in PWM mode will provide the same user experience with better gate driving circuit.

ilyas khan

hi sir …..sir plz tell me that how can i generate pwm of 20KHZ* from ka3525….sir plz plz give the circuit as 20khz is using in my project….
my email id is ..i am waiting of ur kind reply..


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