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PWM frequency generator for LED's

Steveggz

Oct 7, 2017
15
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Oct 7, 2017
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So far I have everything I need to build my remote phosphor light except the PWM frequency generator. The current parts list consists of,
- Cree XT-E LED's
- Mean Well switching power supply
- Mean Well LDD-1500H Buck drivers

I was going to use the Storm X LED controller by CORALUX but it seems very much overkill for my application. The Storm X is used mostly for reef lighting and has a bunch of preprogramed lighting shows. I just need to dim the LDD-1500H's with a PWM frequency source. In addition it's $100 which I don't mind paying if it'll get the job done but I simply can't get a response from the manufacturer to any of my questions.

The generator needs to output 5v PWM frequency required by the drivers and have at least 8 channels of PWM output (I'm using 8 LDD-1500H drivers) and a frequency of 1kHz so the flicker isn't noticeable in video at higher shutter speeds. I only need one knob of control to control the 8 channels.

Can anyone recommend a simple 5v frequency generator with 8 or more channels that can do 1kHz?

Please understand I'm a novice in electronics. The "Adafruit 12-Channel 16-bit PWM LED Driver - SPI Interface - TLC59711" looks interesting if I were to only use it's PWM frequency generating and not the LED powering. Is that possible? https://www.adafruit.com/product/1455
 

BobK

Jan 5, 2010
7,682
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Jan 5, 2010
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You talk about 8 channels, and you want to control them via one knob (potentiometer). That is not 8 channels, that is one channel. A simple 555 circuit would suffice.

Neither of the boards you referenced will dim then via one knob. The Adafruit board has a SPI interface which would need a microcontroller to control it. The other one has buttons to select the the frequency and duty cycle.

What I think you want is a simple '555 PWM controller that runs at 1 KHz and has a potentiometer to control the duty cycle.

Tell us what, exactly you want to happen.

Bob
 

Audioguru

Sep 24, 2016
3,650
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Sep 24, 2016
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3,650
A 1kHz PWM frequency will not cause an old fashioned incandescent light bulb to flicker at high shutter speeds but since LEDs turn on and off extremely quickly then you should not PWM the LEDs for a high shutter speed video.
 

Audioguru

Sep 24, 2016
3,650
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Sep 24, 2016
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I use some LM3914 and 74HC4017 ICs to do LED patterns like that. Some of them fade a few following LEDs.
 
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