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Cultivated Reef

LED Driver and PWM circuit

Nuno Rio

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This one is a much better driver. Much less heat.


You could use the pwm circuit to turn the driver on and off, but it doesn't actually change the current and won't be as efficient as a true current adjustment. It is a cheap way to do it though. Make sure the pwm frequency is pretty high. Anything above 200hz will not flicker.

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also note, that PWM circuit does not work, I use the same drivers evil linked, works spot on...... but the PWM circuit didn't work. Turns out pin 3 on the 555 is the output and needs to go to the FET (In a single LED string with the above driver and the PWM, you will need two N-channel FETs such as the Fairchild FQP50N06L, one for the driver and one for the PWM)


This will work better,


In the above circuit I substituted the .001uF cap for a .01uF cap, and hte 500K pot for a 100K pot, as well as the 1n4148 diodes for the 1n4001 diodes, as well as the IRFD024 FET for the Fairchild FQP50N06L.


In retrospect, I may have goofed with the diodes, I only have about 15%-100% control, this may be because the 1n4148 are fast switching diodes, and the 1n4001 diodes are just regular diodes.

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