Not bright enough.

From this thread I built a pair of LED turn signals that'll do for that application.

As an indoor light for an RV, the LM317 regulator with 15 ohm resistor to set its output, driving three parallel strings of three LEDs just ain't bright enough. (I stuck the all clear prototype in place of bulb #1 on a dual bulb fixture for a night light that won't drain the battery.)

Sooo, what sort of fancy gee-whiz circuits can push some more photons out of 5mm white LEDs without frying them?

Forget the simple stuff with regulators and resistors. Let's see the 'overclocking' stuff. :rock: I still have a lot of these LEDs to experiment with!

I would mesure the current the leds are using to ensure they are getting enought and also the voltage at different points.

I see the specs now
"Wide Viewing Angle with Maximum brightness for White!"
That makes me wonder. Did I miss something on the page besthongkong page? Like REAL numbers?

Thanks

Sorry to hear that your lights aren't bright enough.

As Ken2400 says, you will have to take some voltage readings. Of course since you potted everything you will have to start anew. Potting doesn't help heat dissipation.

Using smaller value resistors will brighten the leds but it could fry them if they get to much voltage. The design is sound but maybe to conservative. There is no secret recipe, more voltage = more light = more heat so if you want them really bright they will have to be cooled. Two ways to do that, heatsinking or air flow.

The other way around is to pulse the leds so they're on only part of the time. The pulse can be fast enough that the human eye can't see that the lights are actually pulsing. Since they're on only part of the time, you can drive them harder.

As far as how this can be achieved, I'll let somebody else more verse in electronics than I am, help you.

Good luck.

Calina said:

The other way around is to pulse the leds so they're on only part of the time. The pulse can be fast enough that the human eye can't see that the lights are actually pulsing. Since they're on only part of the time, you can drive them harder.

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It's true that you can drive LEDs harder if they are only on part of the time (like your TV remote does it).
But then, they are only on part of the time, so you get less light.
Because LEDs are less efficient at higher drive currents, you end up with a little less light as if you were driving them with a continuous current.

I recommend you copy the setup you built and measure the current thru each LED string. You adjust the resistor and / or regulator voltage to achieve nominal (20mA, that should be). You look at it. Too dim ? Try 50mA. Too dim ? Then get more LEDs or high-power LEDs. Drive them at nominal and use so many, that you achieve the amount of light you need. I personally recommend not to overdrive LEDs too much and to cool them appropriately, because they actually do lose their brightness and fail in the real world. It often happens within minutes of operation, looking at cheap Chinese cluster lights.
What abt using CCFLs for your application ? Likely more lumens per Watt and per dollar, also very smooth light and good color rendition, albeit bit old-fashioned and bigger.