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9VDC + 5VDC SMPS for driving LEDS
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TerminalJack505:

--- Quote from: Blade2Raiden on February 10, 2020, 04:40:01 pm ---For those who haven't read all the answers these LED's are current driven so any FET transistor won't do, It'll have to be Bipolar I have access to MMBT3904 and MMBT3906 at work but I don't know their specs yet I'll need to look that up back at home

--- End quote ---

There seems to be some confusion here.  The LEDs will need to be driven from a constant current source (as opposed to a constant voltage source) but that doesn't mean you can't use PWM.
Blade2Raiden:

--- Quote from: T3sl4co1l on February 10, 2020, 04:46:36 pm ---Definitely get a COTS module.  It's not just about safety, it's about performance, reliability, RF emissions -- they've already checked out and solved all those issues for you, the value is very good.

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Yes, I was going for a 30V 2A PSU so I can put LED's in series of 3 then control them, but for it being driven with PWM I'm a little lost, there's another one who told up there it was current driven so I'm not fully certain to understand

mariush:
First of all, you don't want a 9v power supply.
Because the forward voltage of the leds is 8.8...9.3v , you want a power supply that can provide a bit more than 9.3v (unless you use a more expensive BOOST led driver).
I would go with either a 12v or a 24v or a 36v power supply, because they're common voltages and chances are they'll be stocked in higher quantities and they're cheaper.  A 24v psu would allow you to make groups of 2 leds in series and therefore you'd get less current, same for 36v  (make groups of 3 leds)

There are wall warts with these voltages and they're cheap, so you could simply have a standard barrel jack connector on the thing.

8$ : 24v 30w: https://www.digikey.com/product-detail/en/tri-mag-llc/L6R30-240/364-1280-ND/7682643
8$ : 36v 30w: https://www.digikey.com/product-detail/en/tri-mag-llc/L6R30-360/364-1780-ND/7681530
9$ : 12v 30w: https://www.digikey.com/product-detail/en/qualtek/QFWB-30-12-US01/Q1182-ND/8260130

There are lots of led driver chips which allow you to control the brightness either by using a potentiometer or by using a pwm signal from a chip.

Some examples

AL8443QSP : https://www.digikey.com/product-detail/en/diodes-incorporated/AL8843QSP-13/31-AL8843QSP-13CT-ND/10668311

It can do up to 3A, so you can use it with 12v (0.1a x 30= 3A), 24v (1.5A), or 36v (1A if you wire 3 leds in series)

See page 2 of the datasheet for example circuit and explanation for each pin : https://www.diodes.com/assets/Datasheets/AL8843Q.pdf

You set the maximum current with the resistor, and then you can either send a pwm signal on the CTRL pin, or use a potentiometer to adjust brightness)

Monolithic Power MP24833 : https://www.digikey.com/product-detail/en/monolithic-power-systems-inc/MP24833-AGN-Z/1589-1591-1-ND/9433357
Up to 55v , up to 3A

Allegro A6211  (up to 48v, up to 3A, dimming with pwm signal) : https://www.digikey.com/product-detail/en/allegro-microsystems/A6211GLJTR-T/620-1477-1-ND/3597453


Other examples:

up to 2A of current: https://www.digikey.com/product-detail/en/diodes-incorporated/PAM2863ECR/PAM2863ECRDIDKR-ND/4505541




You can power an arduino or pic microcontroller or whatever using a plain linear regulator that can tolerate the voltage you choose (ex if you decide on 36v, then choose a HV version that can tolerate 42v or 60v max.)


tooki:

--- Quote from: TerminalJack505 on February 10, 2020, 04:57:17 pm ---Tooki, nice looking project.  Yeah, that would be a good option for generating the PWM as well.

Dave swapped pins 3 and 7 (discharge and output) on his circuit and got a duty cycle range of about 1% to 99%.  Dave's circuit was running at about 400Hz, which seems like a reasonable frequency for lighting.

--- End quote ---
Thanks for the kind words.

For the sake of flicker-sensitive folks like me, for the love of god don't use a PWM frequency in the hundreds. That's plainly noticeable (and highly distracting/annoying) to us, especially at low duty cycles. (Google the "phantom array effect" to understand why frequencies far higher than 60Hz are needed. FYI, some scientists have calculated that to fully eliminate the possibility of visible LED flicker in all situations, a PWM frequency of 35KHz would be necessary.) In practice, anything above around 3KHz is OK for stationary objects/humans, but since that's an audible frequency, I recommend going higher, so it's unlikely to squeal.

I'd have to try and measure how low mine goes on the oscilloscope, but what I can tell you is that depending on the use case, 1% duty cycle may be way too high. A frequent problem with dimmers is that at a few %, they just turn off. But because human sensitivity to brightness is highly non-linear (we are far more sensitive to small changes on the low end than on the bright end), 1% increments are plainly visible. The LEDs I'm dimming, I often want very dim, less than what I was able to achieve with 8-bit PWM on an Arduino (never mind the lousy PWM frequency). That's just 1/256 duty cycle!


--- Quote from: TerminalJack505 on February 10, 2020, 04:57:17 pm ---At 20kHz, I'm surprised the MOSFET in your circuit doesn't get hot without using the 4050 to drive the gate.

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I was also surprised at how little heat it produces. Like, I expected some heating, but this produces so little that I suspect it'd be happy as a clam even without a heatsink (or just bolted to a case or PCB)! It's a logic-level MOSFET, so at 12V, it's definitely turning fully on (44mΩ RDS(on)), but I guess with being logic-level, even when it's only partly on, it's still super low RDS(on) (at 4V, it's still only 63mΩ). Had I realized it'd run SO cool, I might have even tried a higher frequency like 30-40KHz.

As it is, the incandescent bulb in the switch (despite being run at half its rated current, thanks to the dropper resistor) produces seemingly all the heat in the enclosure.
TerminalJack505:
If you use a 30VDC PSU here's another way to drive the LEDs.  (The LEDs are being simulated with 1 Watt 9V1 Zeners diodes.)

The real-world results obviously won't be as precise as the simulation since the real-world transistors will have variations that the simulation doesn't reflect but you can likely get each of the string's current pretty close to the nominal current rating for the LEDs.

Although not shown this could be driven by PWM simply by putting a MOSFET or BJT on the low side.
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