I wanted to stabilize my LED lighting circuit voltage using a buck/boost converter. When the LED's are dimmed you can see alot of fluctuation from battery voltage change like when the water pump cycles. My concern is with the PWM LED dimmer being driven by the back/boost converter. I'm trying to not let the magic blue smoke out of my PWM dimmers.If this will work, does anyone know of a 5 amp+ buck/boost that will work with a common ground?ThanksDave

THIS is the one I'm using for my current bedroom fixture project. My arrays are 9V, so I have this one both voltage and current limited and it'll run at full output down to .6v of the set point. It appears that the I/O is common ground, but in my case, unfortunately the downstream dimmer runs an isolated ground to the load :(

I've used a booster on a wall wart that was only 11.5 volts and pushed it upto mid 14's, then fed the PWm dimmer with that for a stick and brick project. The Phillips bulb brightness at 14.5 compared to 11.5 was vast. It dimmed pretty well too but got crusty on the low end before the LED just shut off.I did not run it long, as the LED did not illuminate the surface as nicely as hoped, Halogen it will have to be. Warm white LED is still too artificial looking.

ledcomp wrote:I wanted to stabilize my LED lighting circuit voltage using a buck/boost converter. When the LED's are dimmed you can see alot of fluctuation from battery voltage change like when the water pump cycles. My concern is with the PWM LED dimmer being driven by the back/boost converter. I'm trying to not let the magic blue smoke out of my PWM dimmers.If this will work, does anyone know of a 5 amp+ buck/boost that will work with a common ground?ThanksDaveCan you give more details about your existing LED setup and what driver you're using?Any kind of simple switch mode LED driver isn't going to like you pwm'ing the load downstream of the output.Typically the smps will have a pwm input or enable input which accepts a pwm signal for dimming.Alternately with a smps operating in the 10s to 100s of kHz, you can just pwm the driver's power input with a low freq pwm signal (100hz for example). Make sure the driver's soft-start feature is disabled or absent.

I use the $2.95 (8) amp dimmer as found on BuyInCoins.comA 470uf 25-volt electrolytic capacitor inline BEFORE the dimmer helps.

GordonThree wrote:ledcomp wrote:I wanted to stabilize my LED lighting circuit voltage using a buck/boost converter. When the LED's are dimmed you can see alot of fluctuation from battery voltage change like when the water pump cycles. My concern is with the PWM LED dimmer being driven by the back/boost converter. I'm trying to not let the magic blue smoke out of my PWM dimmers.If this will work, does anyone know of a 5 amp+ buck/boost that will work with a common ground?ThanksDaveCan you give more details about your existing LED setup and what driver you're using?Any kind of simple switch mode LED driver isn't going to like you pwm'ing the load downstream of the output.Typically the smps will have a pwm input or enable input which accepts a pwm signal for dimming.Alternately with a smps operating in the 10s to 100s of kHz, you can just pwm the driver's power input with a low freq pwm signal (100hz for example). Make sure the driver's soft-start feature is disabled or absent.This is one of the PWM dimmers that I am using. The other two are similar. http://www.ebay.com/itm/NEW-DIGITAL-12V-60-WATT-PWM-VARIABLE-BRIGHTNESS-LED-DIMMER-DRIVER-KIT-/360569608805?hash=item53f39f9a65The led panels are non-regulated from 2011led from ebay.

LED Dimmer | Good Sam Community

MEXICOWANDERER
Explorer
May 18, 2015
Hmmm. A converter that drives a boost that in turns drives a bucker, that in turn drives another power supply.

HEY RUBE !!!
ledcomp
Explorer
May 18, 2015
SCVJeff wrote:
I seriously doubt you will find a pass through unless you build it. I've not seen a board that is a real buck/boost in the literal term. You could always install a boost board to 20v (or whatever), then back it off with the board above. Those boards are so cheap it's fun to try different ones and combos

So then it is safe to have a boost drive a buck that drives a PWM dimmer?

The board you mentioned above requires an isolated ground, my lighting circuit has a common ground. I have not found a common ground version.
MEXICOWANDERER
Explorer
May 18, 2015
My experience with the B&Bs is similar to gordon three's. With the cost including shipping China Post, the fact that these critters even work, is remarkable. I see my bid for 10 buckers for one cent was successful. Includes shipping. SMD 2-ampere rated. Time to buck those 10-volt 10-watt chips by dialing in the milliamps. For DIY the present is like Alice In Wonderland.
SCVJeff
Explorer
May 18, 2015
I seriously doubt you will find a pass through unless you build it. I've not seen a board that is a real buck/boost in the literal term. You could always install a boost board to 20v (or whatever), then back it off with the board above. Those boards are so cheap it's fun to try different ones and combos
GordonThree
Explorer
May 17, 2015
ledcomp wrote:
GordonThree wrote:
ledcomp wrote:
GordonThree wrote:
How well do the LED perform at 9 volts? A straight buck converter would be easier to find than a boost-buck, forward or sepic converter.

Are you dimming all the leds in the rig, or just a strip of them, or a single fixture?

I was trying to regulate the lighting circuit at the distribution panel. 3 lighting fixtures have a pwm dimmer, the rest are not dimmed. I do not mind loosing some brightness by using a buck converter. I would need to try them at 9 volts, that might be on the low side.

A buck that goes into passthrough when vIN = vOUT would work. Set for 11v or even 12v you'll only see that voltage on an almost dead battery.

I have never seen a buck with passthrough. Do you know where i can get one?

Its not really a feature that would be advertised. You'd have to consult datasheets for the various chips China special is using to build these cheap switchers. Some shutdown when vIN=vOUT, others just pass through. Pick up a few cheapies off flea bay and experiment I suppose.
MEXICOWANDERER
Explorer
May 17, 2015
I Can See It Now Dept -

ROMANTIC CANDLELIGHT DINNER - 2046
After the Carbon Footprint Secretary bans candles...

" Hmmmm; maybe 1.3 Kelvin would be about right with 6, no make that 5 on the Flicker."
ledcomp
Explorer
May 17, 2015
GordonThree wrote:
ledcomp wrote:
GordonThree wrote:
How well do the LED perform at 9 volts? A straight buck converter would be easier to find than a boost-buck, forward or sepic converter.

Are you dimming all the leds in the rig, or just a strip of them, or a single fixture?

I was trying to regulate the lighting circuit at the distribution panel. 3 lighting fixtures have a pwm dimmer, the rest are not dimmed. I do not mind loosing some brightness by using a buck converter. I would need to try them at 9 volts, that might be on the low side.

A buck that goes into passthrough when vIN = vOUT would work. Set for 11v or even 12v you'll only see that voltage on an almost dead battery.

I have never seen a buck with passthrough. Do you know where i can get one?
GordonThree
Explorer
May 17, 2015
ledcomp wrote:
GordonThree wrote:
How well do the LED perform at 9 volts? A straight buck converter would be easier to find than a boost-buck, forward or sepic converter.

Are you dimming all the leds in the rig, or just a strip of them, or a single fixture?

I was trying to regulate the lighting circuit at the distribution panel. 3 lighting fixtures have a pwm dimmer, the rest are not dimmed. I do not mind loosing some brightness by using a buck converter. I would need to try them at 9 volts, that might be on the low side.

A buck that goes into passthrough when vIN = vOUT would work. Set for 11v or even 12v you'll only see that voltage on an almost dead battery.
GordonThree
Explorer
May 17, 2015
SCVJeff wrote:
GordonThree wrote:
How well do the LED perform at 9 volts? A straight buck converter would be easier to find than a boost-buck, forward or sepic converter.

Are you dimming all the leds in the rig, or just a strip of them, or a single fixture?
MY 9v LED arrays are built for 9v. These are flat panels that I stripped all the electronics off and drive them from the new regulator and dimmer. I suspect (unless you can rewire them?) your 12v arrays won't do well @9v.

my led arrays are the same way, three 3v diodes in series, two parallel arrays driven by a constant current led driver in each fixture. there's room on the circuit board to add a microcontroller for dimming, but so far I haven't needed it.
SCVJeff
Explorer
May 17, 2015
GordonThree wrote:
How well do the LED perform at 9 volts? A straight buck converter would be easier to find than a boost-buck, forward or sepic converter.

Are you dimming all the leds in the rig, or just a strip of them, or a single fixture?
MY 9v LED arrays are built for 9v. These are flat panels that I stripped all the electronics off and drive them from the new regulator and dimmer. I suspect (unless you can rewire them?) your 12v arrays won't do well @9v.

Forum Discussion

LED Dimmer

About Technical Issues

Related Content

How to adjust LED headlights?

Dimmer for led lights

Installing a dimmer switch

Dimmer wall switch for interior LED lights?

Dimmer for (+) Side